AU2018369022B2

AU2018369022B2 - Process and system for utilizing energy to treat biological tissue

Info

Publication number: AU2018369022B2
Application number: AU2018369022A
Authority: AU
Inventors: David B. Chang; Jeffrey K. LUTTRULL; Benjamin W. L. Margolis
Original assignee: Ojai Retinal Technology LLC
Current assignee: Ojai Retinal Technology LLC
Priority date: 2017-11-15
Filing date: 2018-07-19
Publication date: 2023-09-21
Anticipated expiration: 2038-07-19
Also published as: AU2018369022A1; JP7130271B2; CN111343936B; EP3703815A4; CA3071937A1; BR112020009238A2; CN111343936A; JP2021502834A; EP3703815A1; WO2019099068A1

Abstract

A process for heat treating biological tissue includes generating treatment radiation having a predetermined wavelength and average power. The treatment radiation is applied to biological tissue, such as retinal tissue, such that at least one treatment spot is formed on the biological tissue and the biological tissue is heat stimulated sufficiently to create a therapeutic effect without destroying the tissue.

Description

PROCESS AND SYSTEM FOR UTILIZING ENERGY TO TREAT BIOLOGICAL TISSUE DESCRIPTION BACKGROUND OF THE INVENTION

[Para 1] The present invention is generally directed to systems and processes

for treating biological tissue, and particularly retinal tissue. More particularly,

the present invention is directed to a process for heat treating retinal or other

biological tissue using radiation, such as light beams, which create a

therapeutic effect to a target tissue without destroying or permanently

damaging the target tissue.

[Para 2] Retinal photocoagulation is a commonly used procedure for treating

retinal diseases, including diabetic retinopathy. Retinal photocoagulation

involves the use of light to create thermal burns in the retinal tissue. These

thermal burns are believed to seal the retina and stop blood vessels from

growing and leaking. Typically, the retinal laser burns are full-thickness in the

areas of retinal pathology and visible at the time of treatment as white or gray

retinal lesions. With time, these lesions develop into focal areas of chorioretinal

scarring and progressive atrophy.

[Para 3] There are different exposure thresholds for retinal lesions that are

haemorrhagic, ophthalmoscopically apparent, or angiographically

demonstrable. A "threshold" lesion is one that is barely visible

ophthalmoscopically at treatment time. A "subthreshold" lesion is one that is not visible at treatment time, but is detectable ophthalmoscopically or angiographically. "Suprathreshold" laser therapy is retinal photocoagulation performed to readily visible end point. In all cases, however, it is believed that actual tissue damage and scarring are necessary in order to create the benefits of the procedure. Photocoagulation has been found to be an effective means of producing retinal scars and has become the technical standard for macular photocoagulation for diabetic macular edema and other retinal diseases for many years.

[Para 4] Although providing a clear advantage compared to no treatment,

current retinal photocoagulation treatments, which create retinal burns and

scarring, have disadvantages and drawbacks. Conventional photocoagulation is

often painful. This may require local anesthesia, which has its own attendant

risks, or alternatively, treatment may be divided into stages over an extended

period of time to minimize treatment pain and post-operative inflammation.

Moreover, transient reduction in visual acuity is common following conventional

photocoagulation.

[Para 5] In fact, thermal tissue damage may be the sole source of many

potential complications of conventional photocoagulation which may lead to

immediate and late visual loss. Such complications include sub-retinal fibrosis,

choroidal neovascularization, and progressive expansion of laser scars.

Inflammation resulting from the tissue destruction may cause or exacerbate

macular edema, induced precipitous contraction of fibrovascular proliferation

with retinal detachment and vitreous hemorrhage, and cause uveitis, serous choroidal detachment, angle closure or hypotony. While some of these complications are rare, others, including treatment pain, progressive scar expansion, visual field loss, decreased night vision, etc. are so common so as to be accepted as inevitable side effects of conventional laser retinal photocoagulation. Due to the inherent retinal damage in conventional photocoagulation treatment, treatment of the fovea and other sensitive areas of the retina is strictly forbidden, notwithstanding the most visually disabling diabetic macular edema occurs in these areas.

[Para 6] Another problem is that the treatment requires the application of a

large number of laser doses to the area of the retina to be treated. This can be

tedious and time-consuming as it is not uncommon for hundreds or even in

excess of one thousand laser spots to be necessary in order to provide a full

treatment. The physician is responsible for ensuring that each laser beam spot

is properly positioned away from sensitive areas of the eye, such as the fovea,

that could result in permanent damage. Point-by-point treatment of a large

number of locations, using a single laser beam sequentially, tends to be a

lengthy procedure, which frequently results in physician fatigue and patient

discomfort.

[Para 7] The inventors have discovered that radiation, such as in the form of

various wavelengths of light, can be applied to retinal tissue in a manner that

does not destroy or permanently damage the retinal tissue, but achieves the

beneficial effects on the eye diseases. The inventors have found that one or

more light beams can be generated and applied to the retinal tissue such that it is therapeutic, yet sublethal to the retinal tissue, and avoids damaging photocoagulation in the retinal tissue, yet provides preventative and protective treatment of the retinal tissue of the eye. It is believed that the process raises the tissue temperature such in a controlled manner to selectively stimulate heat shock protein activation and/or production and facilitation of protein repair, which serves as a mechanism for therapeutically treating the tissue. It is believed that these activated heat shock proteins may reset the diseased retina to its healthy condition by removing and repairing damaged proteins. This then results in improved RPE function, improves retinal function and autoregulation, restorative acute inflammation, reduced chronic inflammation, and systematic immunodulation. The effects of the present invention may slow, stop or even reverse retinal diseases and improve visual function and reduce the risk of visual loss. It is believed that raising tissue temperature in such a controlled manner to selectively stimulate heat shock protein activation without damaging or destroying the tissue has benefits in other tissues as well.

SUMMARY OF THE INVENTION

[Para 8] The present invention resides in a process for heat treating biological

tissue. In accordance with one aspect of the invention, treatment radiation is

generated and applied to retinal tissue in such a manner so as to heat stimulate

the retinal tissue sufficiently to create a therapeutic effect without permanently

damaging or destroying the tissue.

[Para9] More particularly, this aspect is a process for heat treating retinal

tissue, comprising the steps of: selecting a treatment radiation spot size having

a diameter within a range of between 10-700 microns and selecting a total

pulsed treatment radiation train duration within a range of between 30-800

milliseconds. The treatment radiation is generated to comprise a plurality of

light beams having a wavelength between 570 nm and 1300 nm and an average

power of between 1.0 to 37.5 watts. Treatment radiation may be generated

which has a wavelength between 600 nm - 1100 nm and an average power of

between 1.0 and 6.94 watts.

[Para 10] The treatment radiation may be applied to the biological tissue

such that at least one treatment spot having a diameter between 10-700

microns is formed on the biological tissue. At least one treatment spot having

a diameter of between 100-500 microns may also be formed. In accordance

with the above aspect, the treatment radiation is pulsed and the plurality of

light beams are simultaneously applied to retinal tissue for a first period of time

comprising 30-800 milliseconds such that a plurality of spaced apart treatment

radiation spots are formed on the retinal tissue and the retinal tissue is heat

stimulated sufficiently to create a therapeutic effect without permanently

damaging or destroying the tissue and to stimulate heat shock protein

activation in the tissue. The process in accordance with the above aspect

further comprises halting the application of the treatment radiation for an

interval of time comprising between 10 to 90 seconds and re-applying the

treatment radiation to the tissue after the interval of time within a single treatment session so as to controllably raise the temperature of the tissue without destroying the tissue to increase the level of heat shock protein activation in the tissue. The average power of the treatment radiation is selected to be monotonically lower within its range when the treatment radiation spot size is selected to be smaller within its range and/or when the total pulsed treatment radiation train duration is selected to be higher within its range.

[Para 11] The treatment radiation may be applied to at least a portion of the

fovea of the eye.

[Para 12] The tissue may be heated to between six and eleven degrees

Celsius during the application of the treatment radiation to the tissue.

However, the average temperature rise of the tissue over several minutes is

maintained at approximately one degree Celsius or less. This may stimulate

heat shock protein activation in a tissue, and thus create a therapeutic effect,

without destroying the tissue.

[Para 13] A plurality of spaced apart beams of treatment radiation may be

generated and simultaneously applied to the tissue to form a plurality of spaced

apart treatment spots in a first treatment area. During an interval of time,

comprising less than one second, between pulses of treatment radiation

applied to the first treatment area of the tissue, the treatment radiation beams

may be moved and applied to a second treatment area of the tissue sufficiently

spaced apart from the first treatment area of the tissue to avoid thermal tissue

damage of the target tissue. The treatment radiation beams may be repeatedly applied, in an alternating manner during the same treatment session, to each of the first and second treatment areas of the tissue until a predetermined number of applications to each of the first and second treatment areas of the tissue has been achieved.

[Para 14] The treatment radiation is applied to the tissue for a first period of

time, such as less than one second, to stimulate heat shock protein activation

in the tissue. The application of the treatment radiation may halted for an

interval of time that exceeds the first period of time, such as several seconds to

several minutes. The treatment radiation is then reapplied to the tissue after

the interval of time, within a single treatment session, so as to controllably

raise the temperature of the tissue without destroying the tissue to increase the

level of heat shock protein activation in the tissue.

[Para 15] Other features and advantages of the present invention will become

apparent from the following more detailed description, taken in conjunction

with the accompanying drawings, which illustrate, by way of example, the

principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[Para 16] The accompanying drawings illustrate the invention. In such

drawings:

[Para 17] FIGURE - is a graph illustrating absorption of radiation at given

wavelengths by blood and ocular tissues;

[Para 18] FIGURE 2 is a graph depicting properties of melanin and

absorbance of RPE melanin as a function of wavelength;

[Para 19] FIGURE 3 is a graph depicting absorption coefficients of water at

various wavelengths;

[Para 20] FIGURES 4A and 4B are graphs depicting radiation-induced

temperature rise in the lens of an eye as a function of the average radiation

power and time of irradiation;

[Para 21] FIGURE 5 is a graph depicting the increase in water temperature

near the retina as a function of average radiation power for different

wavelengths;

[Para 22] FIGURE 6 is a graph depicting the increase in required power as the

radiation wavelength increases for melanin absorption and heat shock protein

activation;

[Para 23] FIGURES 7A-7C are graphs depicting average power at retinal spots

of varying diameters as a function of the radiation duration for average required

treatment power and maximum allowable average treatment power, in

accordance with the present invention;

[Para 24] FIGURES 8A-8C are graphs depicting the average power density

required for treatment and maximum allowable average treatment power at

varying retinal spot diameters, in accordance with the present invention;

[Para 25] FIGURES 9A and 9B are graphs illustrating the average power of a

laser source compared to a source radius and pulse train duration of the laser;

[Para 26] FIGURES 1OA and 1OB are graphs illustrating the time for the

temperature to decay depending upon the laser source radius and wavelength;

[Para 27] FIGURE 11is a diagrammatic view illustrating a system used to

generate a laser light beam, in accordance with the present invention;

[Para 28] FIGURE 12 is a diagrammatic view of optics used to generate a laser

light geometric pattern, in accordance with the present invention;

[Para 29] FIGURE 13 is a top plan view of an optical scanning mechanism,

used in accordance with the present invention;

[Para 30] FIGURE 14 is a partially exploded view of the optical scanning

mechanism of FIG. 13, illustrating the various component parts thereof;

[Para 31] FIGURE 15 illustrates controlled offsets of exposure of an

exemplary geometric pattern grid of laser spots to treat the target tissue, in

accordance with an embodiment of the present invention;

[Para 32] FIGURE 16 is a diagrammatic view illustrating the use of a

geometric object in the form of a line or bar controllably scanned to treat an

area of the target tissue;

[Para 33] FIGURE 17 is a diagrammatic view similar to FIG. 16, but illustrating

the geometric line or bar rotated to treat the target tissue;

[Para 34] FIGURE 18 is a diagrammatic view illustrating an alternate

embodiment of the system used to generate laser light beams for treating

tissue, in accordance with the present invention;

[Para 35] FIGURE 19 is a diagrammatic view illustrating yet another

embodiment of a system used to generate laser light beams to treat tissue in

accordance with the present invention;

[Para 36] FIGURES 20A-20D are diagrammatic views illustrated in the

application of micropulsed energy to different treatment areas during a

predetermined interval of time, within a single treatment session, and

reapplying the energy to previously treated areas, in accordance with the

present invention;

[Para 37] FIGURES 21-23 are graphs depicting the relationship of treatment

power and time in accordance with the embodiments of the present invention;

[Para 38] FIGURES 24A and 24B are graphs depicting the behavior of HSP

cellular system components over time following a sudden increase in

temperature;

[Para 39] FIGURES 25A-25H are graphs depicting the behavior of HSP cellular

system components in the first minute following a sudden increase in

temperature;

[Para 40] FIGURES 26A and 26B are graphs illustrating variation in the

activated concentrations of HSP and inactivated HSP in the cytoplasmic reservoir

over an interval of one minute, in accordance with the present invention; and

[Para 41] FIGURE 27 is a graph depicting the improvement ratios versus

interval between treatments, in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[Para 42] As shown in the accompanying drawings, and as more fully

described herein, the present invention is directed to a system and method for

heat treating biological tissue. This may be done by delivering radiation, such

as one or more light beams or the like, having energy and application

parameters selected to cause a thermal time-course in tissue to raise the tissue

temperature over a short period of time to a sufficient level to achieve a

therapeutic effect while maintaining an average tissue temperature over a

prolonged period of time below a predetermined level so as to avoid permanent

tissue damage. It is believed that the creation of the thermal time-course

stimulates heat shock protein activation or production and facilitates protein

repair without causing any damage.

[Para 43] The inventors have discovered that electromagnetic radiation can

be applied to retinal tissue in a manner that does not destroy or damage the

retinal tissue while achieving beneficial effects on eye diseases. More

particularly, a laser light beam can be generated that is therapeutic, yet

sublethal to retinal tissue cells and thus avoids damaging photocoagulation in

the retinal tissue which provides preventative and protective treatment of the

retinal tissue of the eye. It is believed that this may be due, at least in part, to

the stimulation and activation of heat shock proteins and the facilitation of

protein repair in the retinal tissue.

[Para 44] Various parameters of the light beam must be taken into account

and selected so that the combination of the selected parameters achieve the therapeutic effect while not permanently damaging the tissue. These parameters include radiation wavelength, radius of the radiation source or spot size formed on the retina, radiation power, application duration, and duty cycle of the pulse train. In particular, radiation wavelength, average radiation power, spot size formed on the retina by the radiation source, and application duration, such as the train duration of a pulsed radiation source are particularly important parameters when generating and applying the treatment radiation to the retina in order to achieve therapeutic effect without destroying or permanently damaging the tissue.

[Para 45] The selection of these parameters may be determined by requiring

that the Arrhenius integral for HSP activation be greater than 1 or unity. At the

same time, the selected parameters must not permanently damage the tissue.

Thus, the Arrhenius integral for damage may also be used, wherein the solved

Arrhenius integral is less than 1 or unity. Alternatively, the FDA/FCC

constraints on energy deposition per unit gram of tissue and temperature rise

as measured over periods of minutes be satisfied so as to avoid permanent

tissue damage. The FDA/FCC requirements on energy deposition and

temperature rise are widely used and can be referenced, for example, at

www.fda.gov/medicaldevices/deviceregulationandguidance/guidancedocument

s/ucm073817.htm#attacha for electromagnetic sources. Generally speaking,

tissue temperature rises of between 60 C and 11° C can create therapeutic

effect, such as by activating heat shock proteins, whereas maintaining the

average tissue temperature over a prolonged period of time, such as over several minutes, such as six minutes, below a predetermined temperature, such as 1° C or less, will not permanently damage the tissue.

[Para 46] As mentioned above, wavelength of the treatment radiation is one

of the parameters which must be determined and selected. The possible

wavelength range is determined at the increased absorption by the tissue, such

as the retina's visual pigments, at the lower end and by the decreased melanin

absorption coupled with the increased water absorption at the upper end.

Although the process of the present invention can be used to treat a variety of

tissues, it has been found to be particularly suitable for treating ocular

disorders and diseases, and particularly retinal disorders. Thus, the parameters

described herein are particularly suited for treatment of such retinal disorders.

[Para 47] With reference to FIG. 1, which illustrates the absorption of

radiation along a spectrum of wavelengths by blood, RPE melanin, macular

pigments, the lens, water, and long wavelength sensitive (LWS) and medium

wavelength sensitive (MWS) visual pigments. FIG. 1 displays the optical density,

or the product of the absorption-per-unit length times the absorption length as

a function of wavelength between 400 nm and 750 nm wavelength of the

radiation, such as within the light spectrum. FIG. 1 shows that above 650 nm,

the absorption is practically all due to the melanin in the RPE. At approximately

570 nm, the sum of the optical densities of the LWS and the MWS pigments and

the blood exceeds the optical density of the melanin. This is not desirable as

the patient will experience visual effects during the treatment due to the

absorption of the visual pigments below 450 nm, the absorption is primarily due to the RPE melanin, blood and the lens. However, absorption by the lens is not desirable as that causes heating of the lens that might result in denaturation of the proteins comprising the lens. Thus, the lower wavelength limit realistically usable by the process of the present invention is determined by undesirable absorption by the visual pigments and other absorbers.

Consequently, a lower extreme wavelength limit would be approximately 570

nm where the melanin and sum of the visual pigment optical densities are

comparable. A preferable lower wavelength limit, however, would be 600 nm,

where the absorption is dominated by the melanin with no visual pigment

absorption, and thus avoiding the patient experiencing visual disturbances

during treatment.

[Para 48] It is believed that the therapeutic effect of the radiation treatment

is due to the activation of HSPs in the RPE due to the laser-induced elevation of

RPE temperature. In the desired operating range of wavelengths, this

temperature elevation is due primarily to the absorption of radiation by the thin

layer (approximately 6 microns of melanin in the anterior portion of the RPE).

FIG. 2 shows the absorbance of the RPE melanin as a function of wavelength

between 250 nm and 700 nm in arbitrary units (AU). It has been found that the

plot could be fit by an exponential: exp[-0.0062X(nm)]. The absorption

coefficient has been found to be 104 cm 1 at X = 810 nm, so that melanin(X)=

104 exp[-0.0062((nm)-810)]. Thus, the absorbance drops off quite rapidly as

wavelength increases. At 1300 nm, for instance, the melanin absorbance is

only 0.048 what it is at 810 nm. At 810 nm, the fraction of the incident radiation that is absorbed by the melanin is 6%. At 1300 nm, this drops to only

0.3%. This means that at 1300 nm, the radiation power due to this effect alone

would have to be increased by a factor of 20 compared to the power at 810 nm

to achieve the same temperature increase.

In addition to the decrease in melanin absorption with increasing

wavelength, the absorption by water in the vitreous increases. The absorption

coefficient of water is a function of wavelength (between 49 nm and 1 mm) is

shown in FIG. 3. As can be seen in FIG. 3, the absorption coefficient of water to

radiation increases from 0.03 cm-1 at 810 nm to 0.3 cm-1 at 1300 nm. This

means that as the wavelength increases above 810 nm, the temperature of the

eye lens and of the vitreous will increase more for a given input laser power.

Between 400 nm and 1500 nm, it appears from FIG. 3 that water()/a(810)

(X/810)5, i.e., awater(A)~ 0.03 [X((nm)/810]5.

[Para 49] With reference now to FIGS. 4A and 4B, the radiation-induced

temperature rise in the lens of the eye as a function of the average radiation

power and time of irradiation for wavelengths of 810 nm and 1300 nm are

shown. The plot is for powers in the range of 0 to 5 watts and for irradiation

times in the range of 0 to 0.8 seconds. It can be seen from FIGS. 4A and 4B

that increasing the wavelength from 810 nm to 1300 nm results in an order of

magnitude increase in the temperature rise of the lens. At the same time, the

resulting temperature rises in the lens for the powers and irradiation times

would not result in denaturation of the lens proteins for either wavelength and

thus while 810 nm would be a preferable wavelength, it is unlikely that an increase in the wavelength to the order of 1300 nm would cause damage to the lens.

[Para 50] The magnitude and effect of temperature increase at the longer

wavelengths near the retina can be larger, however. The reason for this is that

near the lens, the radius of the radiation is of the same order as that of the

lens, approximately 3 mm. Near the retina, however, the radiation is focused to

a much smaller radius. The difference in radii results in a much larger

temperature rise near the retina, in spite of the fact that near the lens thermal

diffusion distances during the irradiation time are much less than the radius,

whereas near the retina the temperature rise is diminished by thermal diffusion.

Due to the thermal diffusion near the lens, the water-absorption-induced

temperature rise there is essentially independent of the spot size.

[Para 51] FIGURE 5 illustrates increase in water temperature near the retina

as a function of average radiation power, the top curve being at a wavelength of

1300 nm and the bottom curve for 810 nm radiation wavelengths. The power

ranges from 0 to 5 watts. FIG. 5 shows that at the 810 nm wavelength, the

temperature rise is small and should not damage the retina. At the 1300 nm

wavelength, the temperature rise can be quite appreciable as the average power

increases. As can be seen in FIG. 5, the temperature rise is 8 K for a power of 2

watts. Nevertheless, as will be shown more fully below, it is unlikely that the

average power levels at this magnitude will be needed. Accordingly, it is

unlikely that for average powers of interest in the invention that increasing the radiation wavelength to the order of 1300 nm should raise the water temperature near the retina to the point where damage is inflicted.

[Para 52] Another consideration is the amount of radiation power attenuation

in the water before the RPE is reached. The power at the retina is obtained

from the power incident on the eye by the factor exp[-L], where a is the

absorption coefficient of water and L is the distance through the eye:

• a(810 nm) = 0.03 cm-1

* o(1300 nm) = 0.3 cm-1

* L = 2.5 cm

[Para 53] Thus, at 810 nm, exp[-0.03x2.5] = 0.93 of the incident radiation

arrives at the retina, whereas at 1300 nm, only exp[-0.3x2.5] = 0.47 of the

incident radiation arrives at the retina.

[Para 54] Accordingly, as the wavelength increases to the order of 1300 nm,

the efficiency of the treatment decreases appreciably. To obtain the same

temperature increase in the RPE, twice as powerful a radiation source would

have to be employed as at 810 nm if the absorption coefficient of the RPE

melanin were the same at the two wavelengths. However, the melanin

absorption coefficient is smaller by a factor of 20. The two effects combined

mean that the radiation power would have to be increased by about 40 times to

achieve the same temperature rise.

[Para 55] From the foregoing, it is apparent that there are two main

consequences of using longer wavelengths, namely, a decrease in the melanin

absorption and an increase in the amount of attenuation in the vitreous due to the increased water absorption. To estimate the impact of the decrease in melanin absorption on the required radiation power, it is enough to recognize that the temperature increase that activates the HSPs is proportional to Pmelanin, where P is the power incident on the retina. To estimate the impact of the increased attenuation in the vitreous, we simply note that the power incident on the retina is related to the power incident on the eye by exp[-waterL]. So if we designate the required radiation power incident on the eye at 810 nm by p(810), the required power at any other wavelength can be approximately written as p(X) = p(810) Exp[0.0062(Xnm - 810)]Exp[0.075 {Xnm /810}5].

[Para 56] The ratio p()/p(810) between 600 nm and 1300 nm wavelengths is

plotted in FIG. 6. It can be seen from FIG. 6 that as the radiation wavelength

increases, the required power for HSP activation increases greatly due to both

the increased water absorption and decreased melanin absorption. It can be

seen from the foregoing that due to the very large increase in required

radiation power for HSP activation as the wavelength is increased, a reasonable

upper limit on the usable wavelength for the process of the present invention is

1300 nm. However, a more preferable upper limit on wavelength is 1100 nm,

where although the power required is still larger than its shorter wavelengths, it

is not nearly as much as higher wavelengths.

[Para 57] From the foregoing, the present invention can be performed in a

broad range of wavelengths between 570 nm to 1300 nm. However, a more

preferable range of wavelengths is 600 nm to 1100 nm. An even more

preferable range of wavelengths is 700 nm to 900 nm, with a particularly preferred operating wavelength at approximately 810 nm. At these wavelengths, the melanin absorption is dominant with the heating primarily in the desired RPE and the wavelength is at a safe distance from the wavelengths where appreciable absorption occurs in the visual pigments at shorter wavelengths or water at longer wavelengths.

[Para 58] In addition to wavelength, the other parameters that need to be

specified in order for one to be able to practice the invention are the duration

of the irradiation at a single spot, the single spot radius of the radiation at the

retina, and the average power P at the retina.

[Para 59] Alternatively, the average radiation power P can be replaced by the

average radiation power density P1 at the retina, where the two quantities are

related simply by Pi = P /(rrR 2), where R designates the radius of the radiation

spot on the retina.

[Para 60] For a repetitive micropulse system of the type used in the

invention, the average radiation power density (fluence) P1 at the retina is

related to the peak radiation power density at the retina multiplied by the duty

cycle dc of the micropulse train. The peak radiation power delivered to the

retina is equal to the peak radiation "dial power" for a single spot times the

efficiency of transmission q of the optical system. The efficiency is typically

about 80%. If the laser illuminates a grid of N spots and has a total peak dial

power of Ppeak, then Pi = n (dc Ppeak/N)/( rR 2 ).

[Para 61] FIGURES 7A-7C show the dependence of the required average

radiation power on spot size and radiation duration. For each figure, two powers are shown, namely, Preset, the average required treatment power (bottom curve), and Pdamage, the maximum allowable average treatment power above which appreciable damage can occur (top curve). The lower curve shows the power which gives a reset Arrhenius integral of 1. The top curve gives a damage threshold Arrhenius integral of 1. The radiation durations range from

0.03 seconds to 0.8 seconds. A radiation wavelength of 810 nm is assumed.

FIG. 7A illustrates the average power in watts at a retinal spot of diameter 10

microns as a function of the radiation duration. FIG. 7B illustrates the average

power in watts at a retinal spot diameter of 200 microns as a function of the

radiation duration. FIG. 7C illustrates the average power in watts at a retinal

spot diameter of 500 microns as a function of the radiation duration.

[Para 62] FIGURES 8A-8C illustrate the dependence of the required radiation

power density (fluence) at the retina, on spot size and micro train duration.

Accordingly, FIG. 8A has a retinal spot diameter of 10 microns, 8B a retinal spot

diameter of 200 microns, and 8C a retinal spot diameter of 500 microns. Once

again, a radiation wavelength of 810 nm is used. Although FIGS. 8A-8C could

be obtained directly from FIGS. 7A-7C simply by dividing the powers of FIGS.

7A-7C by the areas of the spots, they are included for ease of reference.

[Para 63] FIGURES 7 and 8 show that as the treatment duration decreases,

the required powers and power densities increase dramatically. Moreover, the

larger the retinal spot treated, the larger is the required average power.

Furthermore, the larger the retinal spot treated, the smaller is the required

average power density. Although the power at a 500 micron spot is of the order of 75 times larger than the power at a 10 micron spot, the average power does not appear to be excessive. Similarly, for a 10 micron spot, the required power density is of the order of 34 times that for a 500 micron spot, but the higher power densities do not seem to be excessive. However, these treatment spot sizes represent an approximate upper and lower end of the sizes used in accordance with the present invention.

[Para 64] It should be noted, however, that the smaller the treatment spot,

the more spots will be required to treat a given area of the retina. This will

require a longer total treatment time, which is undesirable. Also, the longer

treatment time for a spot, the longer will be the total time required for treating

a given desired area of the retina.

[Para 65] There are also safety limits which must be taken into account in

order to avoid destroying or permanently damaging the retinal tissue. There

are limits on how short the radiation duration with associated increase in power 2 density can be. For nanosecond or picosecond pulses of 1010-1012 watts/cm

of near infrared lasers, such short pulses have been shown to create plasma in

tissue which generates destructive shock waves. Photothermolysis with

exploding tissue has been shown to occur with a 585 nm pulsed laser of

0.0005 seconds duration. Studies with an argon laser (514 nm) have been done

to see when damage to the RPE occurs because of thermal effect and the

shockwave/bubble generation effect. It was found that for a 5 microsecond

pulse, RPE cell damage was always associated with microbubble formation. For

a 50 microsecond pulse, the damage was due mostly to thermal denaturation effects, but there are also some microbubbles formed. For pulses longer than

500 microseconds, the damage was due to thermal effects. The damage

mechanism changes from a purely thermal mechanism at longer pulses to a

thermomechanical mechanism at short pulses, with the transition occurring at

approximately 18 microseconds. It has also been found that short duration red

or longer wavelength continuous wavelength laser applications (see the CW) are

known to have an increased risk of rupturing Bruch's membrane by thermal

explosion/bubble formation, and that can lead to choroidal neovascularation

and visual loss.

[Para 66] From the foregoing, we can conclude about retinal spots and

treatment times that in order to avoid long total treatment times and large

radiation powers and power density, for a wavelength radiation of

approximately 810 nm, a broad range of treatment times of 0.03 seconds to

0.8 seconds may be used, with a preferred range of treatment times of 0.1

seconds to 0.5 seconds. A broad range of retinal spot sizes usable in

accordance with the present invention is 10 microns to 700 microns in

diameter. However, a more preferable range of retinal spot sizes is 100-500

microns in diameter.

[Para 67] The below Tables 1-5 show the required treatment (reset) powers,

damage powers, treatment (reset) power densities, and damage power densities

at the extremes of the ranges for different wavelengths within the range of

wavelengths usable in order to practice the present invention.

[Para 68] Table 1. Treatment power Preset, damage power Pamage, treatment

power densities at retina Pireset, and threshold damage power densities at retina

Plamage as a function of irradiation treatment time tF at a retinal radiation spot

diameter, for X = 570 nm. The powers are in watts, the power densities in

watts/cm2 , time is in seconds, and spot diameters are in microns. The values

of tF are those at the extremes of the suggested treatment ranges.

tF sec Diameter Preset Pdamage Pireset Pidamage seconds prm watts watts watts/sqcm watts/sqcm

0.03 10 0.001541 0.002944 1974 3737 200 0.03864 0.07291 122 232 500 0.19734 0.3726 100 190 0.1 10 0.000966 0.002484 1237 3156 200 0.019159 0.04876 60 155 500 0.0736 0.18768 37 95 0.5 10 0.00023 0.001909 284 2423 100 0.003818 0.032522 12 103 500 0.011362 0.096761 5 49 0.8 10 6.9E-06 0.001748 9.8 2213 100 0.000129 0.029026 0.41 94 500 0.000368 0.082846 0.18 42

[Para 69] Table 2. Treatment power Preset, damage power Pamage, treatment

diameter, for X = 600 nm. The powers are in watts, the power densities in

watts/cm2 , time is in seconds, and spot diameters are in microns. The values

of tF are those at the extremes of the suggested treatment ranges.

0.03 10 0.001809 0.003456 2317 4387

200 0.04536 0.08559 143 272 500 0.23166 0.4374 117 223 0.1 10 0.001134 0.002916 1452 3705 200 0.022491 0.05724 71 182 500 0.0864 0.22032 44 112 0.5 10 0.00027 0.002241 334 2844 100 0.004482 0.038178 14 121 500 0.013338 0.113589 6.8 57 0.8 10 8.1E-06 0.002052 11 2599 100 0.000151 0.034074 0.48 111 500 0.000432 0.097254 0.21 49

[Para 70] Table 3. Treatment power Preset, damage power Pamage, treatment

diameter, for X = 810 nm. The powers are in watts, the power densities in

watts/cm2 , time is in seconds, and spot diameters are in microns. The values

of tF are those at the extremes of the suggested treatment ranges.

0.03 10 0.0067 0.0128 8583 16251 200 0.168 0.317 533 1009 500 0.858 1.62 437 828 0.1 10 0.0042 0.0108 5381 13723 200 0.0833 0.212 265 677 500 0.32 0.816 163 416 0.5 10 0.001 0.0083 1239 10536 100 0.0166 0.1414 52 450 500 0.0494 0.4207 25 214 0.8 10 0.00003 0.0076 42 9626 100 0.00056 0.1262 1.7 412 500 0.0016 0.3602 0.81 183

[Para 71] Table 4. Treatment power Preset, damage power Pamage, treatment

diameter, for X = 1100 nm. The powers are in watts, the power densities in

watts/cm2 , time is in seconds, and spot diameters are in microns. The values

of tF are those at the extremes of the suggested treatment ranges.

0.03 10 0.05695 0.1088 72955 138133 200 1.428 2.6945 4530 8576 500 7.293 13.77 3714 7038 0.1 10 0.0357 0.0918 45738 116645 200 0.70805 1.802 2252 5754 500 2.72 6.936 1385 3536 0.5 10 0.0085 0.07055 10531 89556 100 0.1411 1.2019 449 3825 500 0.4199 3.57595 214 1819 0.8 10 0.000255 0.0646 363 81821 100 0.00476 1.0727 15 3502 500 0.0136 3.0617 6.9 1555

[Para 72] Table 5. Treatment power Preset, damage power Pamage, treatment

diameter, for X = 1300 nm. The powers are in watts, the power densities in

watts/cm2 , time is in seconds, and spot diameters are in microns. The values

of tF are those at the extremes of the suggested treatment ranges. tF sec Diameter Preset Pdamage Pireset Pidamage seconds prm watts watts watts/sqcm watts/sqcm

0.03 10 0.3082 0.5888 394818 747546 200 7.728 14.582 24518 46414 500 39.468 74.52 20102 38088 0.1 10 0.1932 0.4968 247526 631258 200 3.8318 9.752 12190 31142

500 14.72 37.536 7498 19136 0.5 10 0.046 0.3818 56994 484656 100 0.7636 6.5044 2433 20700 500 2.2724 19.3522 1159 9844 0.8 10 0.00138 0.3496 1966 442796 100 0.02576 5.8052 82 18952 500 0.0736 16.5692 37 8418

[Para 73] The inventors have discovered that generating one or more

radiation beams, such as coherent (laser) or non-coherent light beams within

the range indicated above, with a corresponding appropriate duration,

treatment spot size, and average radiation power or average radiation power

density at the retina creates desirable retinal photostimulation without any

visible burn areas or tissue destruction. Appropriate selection of the radiation

generation and energy application parameters raises the retinal tissue at least

up to a therapeutic level but below a cellular or tissue lethal level so as to avoid

destroying, burning or otherwise damaging the retinal tissue. The appropriate

combination of these parameters generates a subthreshold, sublethal

micropulsed radiation light beam(s) which when appropriately applied to the

retinal or other biological tissue heat stimulates the tissue sufficiently to create

a therapeutic effect without destroying the tissue. The term "subthreshold" as

used herein in connection with the invention means not only that no visible

burn areas or tissue destruction is formed, but that the treated areas show no

signs of burns, lesions or tissue damage ophthalmoscopically or

angiographically, and thus is termed by the inventors as "true subthreshold"

retinal photostimulation. Thus, the present invention can be used to treat the

entire retina, including sensitive areas such as the fovea, without the risk of damage or vision loss. This is referred to herein as "subthreshold diode micropulse laser treatment" (SDM).

[Para 74] SDM does not produce laser-induced retinal damage

(photocoagulation), and has no known adverse treatment effect, and has been

reported to be an effective treatment in a number of retinal disorders (including

diabetic macular edema (DME) proliferative diabetic retinopathy (PDR), macular

edema due to branch retinal vein occlusion (BRVO), central serous

chorioretinopathy (CSR), reversal of drug tolerance, and prophylactic treatment

of progressive degenerative retinopathies such as dry age-related macular

degeneration, Stargardts' disease, cone dystrophies, and retinitis pigmentosa.

The safety of SDM is such that it may be used transfoveally in eyes with 20/20

visual acuity to reduce the risk of visual loss due to early fovea-involving DME.

[Para 75] A mechanism through which SDM might work is the generation or

activation of heat shock proteins (HSPs). Despite a near infinite variety of

possible cellular abnormalities, cells of all types share a common and highly

conserved mechanism of repair: heat shock proteins (HSPs). HSPs are elicited

almost immediately, in seconds to minutes, by almost any type of cell stress or

injury. In the absence of lethal cell injury, HSPs are extremely effective at

repairing and returning the viable cell toward a more normal functional state.

Although HSPs are transient, generally peaking in hours and persisting for a few

days, their effects may be long lasting. HSPs reduce inflammation, a common

factor in many disorders.

[Para 76] Laser or other radiation treatment can induce HSP production or

activation and alter cytokine expression. The more sudden and severe the non

lethal cellular stress (such as laser irradiation), the more rapid and robust HSP

activation. Thus, a burst of repetitive low temperature thermal spikes at a very

steep rate of change (- 7°C elevation with each 100ps micropulse, or

70,000°C/sec) produced by each SDM exposure is especially effective in

stimulating activation of HSPs, particularly compared to non-lethal exposure to

subthreshold treatment with continuous wave lasers, which can duplicate only

the low average tissue temperature rise.

[Para 77] Laser or other radiation wavelengths below 550 nm produce

increasingly cytotoxic photochemical effects. At 810 nm, SDM produces

photothermal, rather than photochemical, cellular stress. Thus, SDM is able to

affect the tissue without damaging it. The clinical benefits of SDM are thus

primarily produced by sub-morbid photothermal cellular HSP activation. In

dysfunctional cells, HSP stimulation by SDM results in normalized cytokine

expression, and consequently improved structure and function. The

therapeutic effects of this "low-intensity"laser/tissue interaction are then

amplified by "high-density" laser application, recruiting all the dysfunctional

cells in the targeted tissue area by densely / confluently treating a large tissue

area, including all areas of pathology, thereby maximizing the treatment effect.

These principles define the treatment strategy of SDM described herein.

[Para 78] Because normally functioning cells are not in need of repair, HSP

stimulation in normal cells would tend to have no notable clinical effect. The

"patho-selectivity" of near infrared laser effects, such as SDM, affecting sick

cells but not affecting normal ones, on various cell types is consistent with

clinical observations of SDM. SDM has been reported to have a clinically broad

therapeutic range, unique among retinal laser modalities, consistent with

American National Standards Institute "Maximum Permissible Exposure"

predictions. While SDM may cause direct photothermal effects such as entropic

protein unfolding and disaggregation, SDM appears optimized for clinically safe

and effective stimulation of HSP-mediated repair.

[Para 79] As noted above, while SDM stimulation of HSPs is non-specific with

regard to the disease process, the result of HSP mediated repair is by its nature

specific to the state of the dysfunction. HSPs tend to fix what is wrong,

whatever that might be. Thus, the observed effectiveness of SDM in retinal

conditions as widely disparate as BRVO, DME, PDR, CSR, age-related and

genetic retinopathies, and drug-tolerant NAMD. Conceptually, this facility can

be considered a sort of "Reset to Default" mode of SDM action. For the wide

range of disorders in which cellular function is critical, SDM normalizes cellular

function by triggering a "reset" (to the "factory default settings") via HSP

mediated cellular repair.

[Para 80] The inventors have found that SDM treatment of patients suffering

from age-related macular degeneration (AMD) can slow the progress or even

stop the progression of AMD. Most of the patients have seen significant

improvement in dynamic functional logMAR mesoptic visual acuity and

mesoptic contrast visual acuity after the SDM treatment. It is believed that SDM works by targeting, preserving, and "normalizing" (moving toward normal) function of the retinal pigment epithelium (RPE).

[Para 81] SDM has also been shown to stop or reverse the manifestations of

the diabetic retinopathy disease state without treatment-associated damage or

adverse effects, despite the persistence of systemic diabetes mellitus. On this

basis it is hypothesized that SDM might work by inducing a return to more

normal cell function and cytokine expression in diabetes-affected RPE cells,

analogous to hitting the "reset" button of an electronic device to restore the

factory default settings. Based on the above information and studies, SDM

treatment may directly affect cytokine expression via heat shock protein (HSP)

activation in the targeted tissue. As heat shock proteins play a role in

responding to a large number of abnormal conditions in body tissue other than

eye tissue, it is believed that similar systems and methodologies can be

advantageously used in treating such abnormal conditions, infections, etc.

[Para 82] As indicated above, subthreshold diode micropulse light (SDM)

photostimulation has been effective in stimulating direct repair of slightly

misfolded proteins in eye tissue. Besides HSP activation, another way this may

occur is because the spikes in temperature caused by the micropulses in the

form of a thermal time-course allows diffusion of water inside proteins, and

this allows breakage of the peptide-peptide hydrogen bonds that prevent the

protein from returning to its native state. The diffusion of water into proteins

results in an increase in the number of restraining hydrogen bonds by a factor on the order of a thousand. Thus, it is believed that this process could be applied to other tissues and diseases advantageously as well.

[Para 83] As explained above, the energy source to be applied to the target

tissue will have energy and operating parameters which must be determined

and selected so as to achieve the therapeutic effect while not permanently

damaging the tissue. Using a light beam energy source, such as a laser light

beam, as an example, the laser wavelength, the radius of the laser treatment

spot, the average laser power and total pulse train duration parameters must be

taken into account. Adjusting or selecting one of these parameters can have an

effect on at least one other parameter.

[Para 84] FIGS. 9A and 9B illustrate graphs showing the average power in

watts as compared to the laser source radius (between 0.1 cm and 0.4 cm) and

pulse train duration (between 0.1 and 0.6 seconds). FIG. 9A shows a

wavelength of 880 nm, whereas FIG. 1OB has a wavelength of 1000 nm. It can

be seen in these figures that the required power decreases monotonically as the

radius of the source decreases, as the total train duration increases, and as the

wavelength decreases. The preferred parameters for the radius of the laser

source is 1 mm-4 mm. For a wavelength of 880 nm, the minimum value of

power is 0.55 watts, with a radius of the laser source being 1 mm, and the total

pulse train duration being 600 milliseconds. The maximum value of power for

the 880 nm wavelength is 52.6 watts when the laser source radius is 4 mm and

the total pulse drain duration is 100 milliseconds. However, when selecting a

laser having a wavelength of 1000 nm, the minimum power value is 0.77 watts with a laser source radius of 1 mm and a total pulse train duration of 600 milliseconds, and a maximum power value of 73.6 watts when the laser source radius is 4 mm and the total pulse duration is 100 milliseconds. The corresponding peak powers, during an individual pulse, are obtained from the average powers by dividing by the duty cycle.

[Para 85] The volume of the tissue region to be heated is determined by the

wavelength, the absorption length in the relevant tissue, and by the beam

width. The total pulse duration and the average laser power determine the total

energy delivered to heat up the tissue, or power density per area of tissue, and

the duty cycle of the pulse train gives the associated spike, or peak, power

associated with the average laser power. Preferably, the pulsed energy source

energy parameters are selected so that approximately 20 to 40 joules of energy

is absorbed by each cubic centimeter of the target tissue.

[Para 86] The absorption length is very small in the thin melanin layer in the

retinal pigmented epithelium. In other parts of the body, the absorption length

is not generally that small. In wavelengths ranging from 400 nm to 2000 nm,

the penetration depth and skin is in the range of 0.5 mm to 3.5 mm. The

penetration depth into human mucous tissues is in the range of 0.5 mm to 6.8

mm. Accordingly, the heated volume will be limited to the exterior or interior

surface where the radiation source is placed, with a depth equal to the

penetration depth, and a transverse dimension equal to the transverse

dimension of the radiation source. Since the light beam energy source is used

to treat diseased tissues near external surfaces or near internal accessible surfaces, a source radii of between 1 mm to 4 mm and operating a wavelength of 880 nm yields a penetration depth of approximately 2.5 mm and a wavelength of 1000 nm yields a penetration depth of approximately 3.5 mm.

[Para 87] It has been determined that the target tissue can be heated to up to

approximately 110 C for a short period of time, such as less than one second, to

create the therapeutic effect of the invention while maintaining the target tissue

average temperature to a lower temperature range, such as less than 60 C or

even 1 C or less over a prolonged period of time, such as several minutes. The

selection of the duty cycle and the total pulse train duration provide time

intervals in which the heat can dissipate. A duty cycle of less than 10%, and

preferably between 2.5% and 5%, with a total pulse duration of between 100

milliseconds and 600 milliseconds has been found to be effective. FIGS. 1OA

and 1OB illustrate the time to decay from 100 C to 10 C for a laser source having

a radius of between 0.1 cm and 0.4 cm with the wavelength being 880 nm in

FIG. 1OA and 1000 nm in FIG. 1OB. It can be seen that the time to decay is less

when using a wavelength of 880 nm, but either wavelength falls within the

acceptable requirements and operating parameters to achieve the benefits of

the present invention while not causing permanent tissue damage.

[Para 88] It has been found that the average temperature rise of the desired

target region increasing at least 60C and up to 11° C, and preferably

approximately 100C, during the total irradiation period results in HSP

activation. The control of the target tissue temperature is determined by

choosing source and target parameters such that the Arrhenius integral for HSP activation is larger than 1, while at the same time assuring compliance with the conservative FDA/FCC requirements for avoiding damage or a damage

Arrhenius integral being less than 1.

[Para 89] In order to meet the conservative FDA/FCC constraints to avoid

permanent tissue damage, for light beams and other electromagnetic radiation

sources, the average temperature rise of the target tissue over any six-minute

period is 1 C or less. FIGS. 10A and 1OB above illustrate the typical decay

times required for the temperature in the heated target region to decrease by

thermal diffusion from a temperature rise of approximately 100 C to 10 C as can

be seen in FIG. 10A when the wavelength is 880 nm and the source diameter is

1 millimeter, the temperature decay time is 16 seconds. The temperature

decay time is 107 seconds when the source diameter is 4 mm. As shown in

FIG. 1OB, when the wavelength is 1000 nm, the temperature decay time is 18

seconds when the source diameter is 1 mm and 136 seconds when the source

diameter is 4 mm. This is well within the time of the average temperature rise

being maintained over the course of several minutes, such as 6 minutes or less.

While the target tissue's temperature is raised, such as to approximately 10 C,

very quickly, such as in a fraction of a second during the application of the

energy source to the tissue, the relatively low duty cycle provides relatively long

periods of time between the pulses of energy applied to the tissue and the

relatively short pulse train duration ensure sufficient temperature diffusion and

decay within a relatively short period of time comprising several minutes, such

as 6 minutes or less, that there is no permanent tissue damage.

[Para90] The absorption properties of tissues differ. The tissue water

content can vary from one tissue type to another, however, there is an observed

uniformity of the properties of tissues at normal or near normal conditions

which has allowed publication of tissue parameters that are widely used by

clinicians in designing treatments. Below are tables illustrating the properties

of electromagnetic waves in biological media, with Table 6 relating to muscle,

skin and tissues with high water content, and Table 7 relating to fat, bone and

tissues with low water content.

[Para 91] Table 6. Properties of Electromagnetic Waves in Biological Media: Muscle, Skin, and Tissues with High Water Content Reflection Coefficient Wavelength Dielectric Conductivity Wavelength Depth of Air-Muscle Interface Muscle-Fat Interface Frequency in Air Constant a-H XH Penetration (MHz) (cm) €H (mho/m) (cm) (cm) r 0 r 0 1 30000 2000 0.400 436 91.3 0.982 +179 10 3000 160 0.625 118 21.6 0.956 +178 27.12 1106 113 0.612 68.1 14.3 0.925 +177 0.651 -11.13 40.68 738 97.3 0.693 51.3 11.2 0.913 +176 0.652 -10.21 100 300 71.7 0.889 27 6.66 0.881 +175 0.650 -7.96 200 150 56.5 1.28 16.6 4.79 0.844 +175 0.612 -8.06 300 100 54 1.37 11.9 3.89 0.825 +175 0.592 -8.14 433 69.3 53 1.43 8.76 3.57 0.803 +175 0.562 -7.06 750 40 52 1.54 5.34 3.18 0.779 +176 0.532 -5.69 915 32.8 51 1.60 4.46 3.04 0.772 +177 0.519 -4.32 1500 20 49 1.77 2.81 2.42 0.761 +177 0.506 -3.66 2450 12.2 47 2.21 1.76 1.70 0.754 +177 0.500 -3.88 3000 10 46 2.26 1.45 1.61 0.751 +178 0.495 -3.20 5000 6 44 3.92 0,89 0.788 0.749 +177 0.502 -4.95 5800 5.17 43.3 4.73 0.775 0.720 0.746 +177 0.502 -4.29 8000 3,75 40 7.65 0.578 0.413 0.744 +176 0.513 -6.65 10000 3 39.9 10.3 0.464 0.343 0.743 +176 0.518 -5.95

[Para 92] Table 7. Properties of Electromagnetic Waves in Biological Media: Fat, Bone, and Tissues with Low Water Content Reflection Coefficient

Wavelength Dielectric Conductivity Wavelength Depth of Air-Fat Interface Fat-Muscle Interface Frequency in Air Constant c-L, XL (cm) r 0 r 0

1 30000 27212 1TT6' 20 10.9-43.2 241 159 0.660 +174 0.651 +169 40.68 738 14.6 12.6-52.8 187 118 0.617 +173 0.652 +170 100 300 7.45 19.1-75.9 106 60.4 0.511 +168 0.650 +172 200 150 5.95 25.8-94.2 59.7 39.2 0.458 +168 0.612 +172

300 100 5.7 31.6-107 41 32.1 0.438 +169 0.592 +172 433 69.3 5.6 37.9-118 28.8 26.2 0.427 +170 0.562 +173 750 40 5.6 49.8-138 16.8 23 0.415 +173 0.532 +174

915 32.8 5.6 55.6-147 13.7 17.7 0.417 +173 0.519 +176 1500 20 5.6 70.8-171 8.41 13.9 0.412 +174 0.506 +176 2450 12.2 5.5 96.4-213 5.21 11.2 0.406 +176 0.500 +176 3000 10 5.5 110-234 4.25 9.74 0.406 +176 0.495 +177 5000 6 5.5 162-309 2.63 6.67 0.393 +176 0.502 +175 5900 5.17 5.05 186-338 2.29 5.24 0.388 +176 0.502 +176 8000 3.75 4.7 255-431 1.73 4.61 0.371 +176 0.513 +173 10000 3 4.5 324-549 1.41 3.39 0.363 +175 0.518 +174,

[Para93] The pulse train mode of energy delivery has a distinct advantage

over a single pulse or gradual mode of energy delivery, as far as the activation

of remedial HSPs and the facilitation of protein repair is concerned. There are

two considerations that enter into this advantage. First, a big advantage for

HSP activation and protein repair in an SDM energy delivery mode comes from

producing a spike temperature of the order of 100 C. This large rise in

temperature has a big impact on the Arrhenius integrals that describe

quantitatively the number of HSPs that are activated and the rate of water

diffusion into the proteins that facilitates protein repair. This is because the

temperature enters into an exponential that has a big amplification effect.

[Para94] It is important that the temperature rise not remain at the high

value (100C or more) for long, because then it would violate the FDA and FCC

requirements that over periods of minutes the average temperature rise must

be less than 10 C.

[Para95] An SDM mode of energy delivery uniquely satisfies both of these

foregoing considerations byjudicious choice of the power, pulse time, pulse

interval, and the volume of the target region to be treated. The volume of the

treatment region enters because the temperature must decay from its high

value of the order of 10 C fairly rapidly in order for the long term average temperature rise not to exceed the long term FDA/FCC limit of 10 C or less for electromagnetic radiation energy sources.

[Para96] With reference now to FIG. 11, a schematic diagram is shown of a

system for generating electromagnetic energy radiation, such as laser light,

embodying SDM. The system, generally referred to by the reference number

20, includes a treatment radiation generator 22, such as for example the 810

nm near infrared micropulsed diode laser in the preferred embodiment. It will

be understood that the treatment radiation may comprise electromagnetic

radiation having a wavelength between 570 nm and 1300 nm, and as such may

comprise coherent or non-coherent light beams. However, a coherent laser

beam is particularly preferred and used in the description herein as an example.

[Para97] The laser generates a laser light beam which is passed through

optics, such as an optical lens and/or mask or a plurality of optical lenses

and/or masks 24, as needed. The laser projector optics 24 pass the shaped

light beam to a delivery device 26, for projecting the laser beam light onto the

target tissue of the patient. It will be understood that the box labeled 26 can

represent both the laser beam projector or delivery device as well as a viewing

system/camera, such as an endoscope, or comprise two different components

in use. The viewing system/camera 26 provides feedback to a display monitor

28, which may also include the necessary computerized hardware, data input

and controls, etc. for manipulating the laser 22, the optics 24, and/or the

projection/viewing components 26.

[Para98] With reference now to FIG. 12, in one embodiment, a plurality of

radiation light beams are generated, each of which has parameters selected so

that a target tissue temperature may be controllably raised to therapeutically

treat the target tissue without destroying or permanently damaging the target

tissue. This may be done, for example, by passing the laser light beam 30

through optics which diffract or otherwise generate a plurality of laser light

beams from the single laser light beam 30 having the selected parameters. For

example, the laser light beam 30 may be passed through a collimator lens 32

and then through a mask 34. In a particularly preferred embodiment, the mask

34 comprises a diffraction grating. The mask/diffraction grating 34 produces a

geometric object, or more typically a geometric pattern of simultaneously

produced multiple laser spots or other geometric objects. This is represented

by the multiple laser light beams labeled with reference number 36.

Alternatively, the multiple laser spots may be generated by a plurality of fiber

optic waveguides.

[Para99] Either method of generating laser spots allows for the creation of a

large number of laser spots simultaneously over a very wide treatment field. In

fact, a very high number of laser spots, perhaps numbering in the dozens or

hundreds or more could be simultaneously generated to cover a given area of

the target tissue, or possibly even the entirety of the target tissue. The present

invention can use a plurality of simultaneously generated and applied

therapeutic light beams or spots, such as numbering in the dozens or even

hundreds, as the parameters and methodology of the present invention create therapeutically effective yet non-destructive and non-permanently damaging treatment. A wide array of simultaneously applied small separated laser spot applications may be desirable as such avoids certain disadvantages and treatment risks known to be associated with large laser spot applications.

[Para 1001 Using optical features with a feature size on par with the

wavelength of the laser employed, for example using a diffraction grating, it is

possible to take advantage of quantum mechanical effects which permits

simultaneous application of a very large number of laser spots for a very large

target area. The individual spots produced by such diffraction gratings are all

of a similar optical geometry to the input beam, with minimal power variation

for each spot. The result is a plurality of laser spots with adequate irradiance to

produce harmless yet effective treatment application, simultaneously over a

large target area. The present invention also contemplates the use of other

geometric objects and patterns generated by other diffractive optical elements.

[Para 1011 The laser light passing through the mask 34 diffracts, producing a

periodic pattern a distance away from the mask 34, shown by the laser beams

labeled 36 in FIG. 12. The single laser beam 30 has thus been formed into

dozens or even hundreds of individual laser beams 36 so as to create the

desired pattern of spots or other geometric objects. These laser beams 36 may

be passed through additional lenses, collimators, etc. 38 and 40 in order to

convey the laser beams and form the desired pattern. Such additional lenses,

collimators, etc. 38 and 40 can further transform and redirect the laser beams

36 as needed.

[Para 102] Arbitrary patterns can be constructed by controlling the shape,

spacing and pattern of the optical mask 34. The pattern and exposure spots

can be created and modified arbitrarily as desired according to application

requirements by experts in the field of optical engineering. Photolithographic

techniques, especially those developed in the field of semiconductor

manufacturing, can be used to create the simultaneous geometric pattern of

spots or other objects.

[Para 103] Although hundreds or even thousands of simultaneous laser spots

could be generated and created and formed into patterns to be simultaneously

applied to the tissue, due to the requirements of not overheating the tissue,

there are constraints on the number of treatment spots or beams which can be

simultaneously used in accordance with the present invention. Each individual

laser beam or spot requires a minimum average power over a train duration to

be effective. However, at the same time, tissue cannot exceed certain

temperature rises without becoming damaged. For example, using an 810 nm

wavelength laser, the number of simultaneous spots generated and used could

number from as few as 1 and up to approximately 100 when a 0.04 (4%) duty

cycle and a total train duration of 0.3 seconds (300 milliseconds) is used. The

water absorption increases as the wavelength is increased. For shorter

wavelengths, e.g., 577 nm, the laser power can be lower. For example, at 577

nm, the power can be lowered by a factor of 4 for the invention to be effective.

Accordingly, there can be as few as a single laser spot or up to approximately

400 laser spots when using the 577 nm wavelength laser light, while still not

harming or damaging the tissue.

[Para 104] Typically, the system of the present invention incorporates a

guidance system to ensure complete and total retinal treatment with retinal

photostimulation. Fixation/tracking/registration systems consisting of a

fixation target, tracking mechanism, and linked to system operation can be

incorporated into the present invention. In a particularly preferred

embodiment, the geometric pattern of simultaneous laser spots is sequentially

offset so as to achieve confluent and complete treatment of the surface.

[Para 1051 This can be done in a controlled manner using an optical scanning

mechanism 50. FIGS. 13 and 14 illustrate an optical scanning mechanism 50 in

the form of a MEMS mirror, having a base 52 with electronically actuated

controllers 54 and 56 which serve to tilt and pan the mirror 58 as electricity is

applied and removed thereto. Applying electricity to the controller 54 and 56

causes the mirror 58 to move, and thus the simultaneous pattern of laser spots

or other geometric objects reflected thereon to move accordingly on the retina

of the patient. This can be done, for example, in an automated fashion using

electronic software program to adjust the optical scanning mechanism 50 until

complete coverage of the retina, or at least the portion of the retina desired to

be treated, is exposed to the phototherapy. The optical scanning mechanism

may also be a small beam diameter scanning galvo mirror system, or similar

system, such as that distributed by Thorlabs. Such a system is capable of

scanning the lasers in the desired offsetting pattern.

[Para 106] The pattern of spots are offset at each exposure so as to create

space between the immediately previous exposure to allow heat dissipation and

prevent the possibility of heat damage or tissue destruction. Thus, as

illustrated in FIG. 15, the pattern, illustrated for exemplary purposes as a grid

of sixteen spots, is offset each exposure such that the laser spots occupy a

different space than previous exposures. It will be understood that the

diagrammatic use of circles or empty dots as well as filled dots are for

diagrammatic purposes only to illustrate previous and subsequent exposures of

the pattern of spots to the area, in accordance with the present invention. The

spacing of the laser spots prevents overheating and damage to the tissue.

Typically, the treatment spots are spaced apart from one another by a distance

of at least one-half diameter of the treatment spot, and more preferably

between at least one and two diameters away from one another to prevent

overheating and damage. It will be understood that this occurs until the entire

target tissue to be treated has received phototherapy, or until the desired effect

is attained. This can be done, for example, by applying electrostatic torque to a

micromachined mirror, as illustrated in FIGS. 13 and 14. By combining the use

of small laser spots separated by exposure free areas, prevents heat

accumulation, and grids with a large number of spots per side, it is possible to

atraumatically and invisibly treat large target areas with short exposure

durations far more rapidly than is possible with current technologies.

[Para 107] By rapidly and sequentially repeating redirection or offsetting of

the entire simultaneously applied grid array of spots or geometric objects, complete coverage of the target, can be achieved rapidly without thermal tissue injury. This offsetting can be determined algorithmically to ensure the fastest treatment time and least risk of damage due to thermal tissue, depending on laser parameters and desired application.

[Para 108] The following has been modeled using the Fraunhoffer

Approximation. With a mask having a nine by nine square lattice, with an

aperture radius 9pm, an aperture spacing of 600pm, using a 890nm

wavelength laser, with a mask-lens separation of 75mm, and secondary mask

size of 2.5mm by 2.5mm, the following parameters will yield a grid having

nineteen spots per side separated by 133pm with a spot size radius of 6pm.

The number of exposures "m" required to treat (cover confluently with small

spot applications) given desired area side-length "A", given output pattern

spots per square side "n", separation between spots "R", spot radius "r" and

desired square side length to treat area "A", can be given by the following

formula:

A 2 m = -floor

[Para 109] With the foregoing setup, one can calculate the number of

operations m needed to treat different field areas of exposure. For example, a

3mm x 3mm area, which is useful for treatments, would require 98 offsetting

operations, requiring a treatment time of approximately thirty seconds.

Another example would be a 3 cm x 3 cm area, representing the entire human

retinal surface. For such a large treatment area, a much larger secondary mask size of 25mm by 25mm could be used, yielding a treatment grid of 190 spots per side separated by 133pm with a spot size radius of 6pm. Since the secondary mask size was increased by the same factor as the desired treatment area, the number of offsetting operations of approximately 98, and thus treatment time of approximately thirty seconds, is constant.

[Para 1101 Of course, the number and size of spots produced in a

simultaneous pattern array can be easily and highly varied such that the

number of sequential offsetting operations required to complete treatment can

be easily adjusted depending on the therapeutic requirements of the given

application.

[Para 111 Furthermore, by virtue of the small apertures employed in the

diffraction grating or mask, quantum mechanical behavior may be observed

which allows for arbitrary distribution of the laser input energy. This would

allow for the generation of any arbitrary geometric shapes or patterns, such as

a plurality of spots in grid pattern, lines, or any other desired pattern. Other

methods of generating geometric shapes or patterns, such as using multiple

fiber optical fibers or microlenses, could also be used in the present invention.

Time savings from the use of simultaneous projection of geometric shapes or

patterns permits the treatment fields of novel size, such as the 1.2 cm 2 area to

accomplish whole-retinal treatment, in a single clinical setting or treatment

session.

[Para 112] With reference now to FIG. 16, instead of a geometric pattern of

small laser spots, the present invention contemplates use of other geometric objects or patterns. For example, a single line 60 of laser light, formed by the continuously or by means of a series of closely spaced spots, can be created.

An offsetting optical scanning mechanism can be used to sequentially scan the

line over an area, illustrated by the downward arrow in FIG. 16.

[Para 113] With reference now to FIG. 17, the same geometric object of a line

60 can be rotated, as illustrated by the arrows, so as to create a circular field of

phototherapy. The potential negative of this approach, however, is that the

central area will be repeatedly exposed, and could reach unacceptable

temperatures. This could be overcome, however, by increasing the time

between exposures, or creating a gap in the line such that the central area is

not exposed.

[Para 1141 The field of photobiology reveals that different biologic effects may

be achieved by exposing target tissues to lasers of different wavelengths. The

same may also be achieved by consecutively applying multiple lasers of either

different or the same wavelength in sequence with variable time periods of

separation and/or with different irradiant energies. The present invention

anticipates the use of multiple laser, light or radiant wavelengths (or modes)

applied simultaneously or in sequence to maximize or customize the desired

treatment effects. This method also minimizes potential detrimental effects.

The optical methods and systems illustrated and described above provide

simultaneous or sequential application of multiple wavelengths.

[Para 115] FIGURE 18 illustrates diagrammatically a system which couples

multiple treatment light sources into the pattern-generating optical subassembly described above. Specifically, this system 20' is similar to the system 20 described in FIG. 11 above. The primary differences between the alternate system 20' and the earlier described system 20 is the inclusion of a plurality of laser consoles, the outputs of which are each fed into a fiber coupler

42. Each laser console may supply a laser light beam having different

parameters, such as of a different wavelength. The fiber coupler produces a

single output that is passed into the laser projector optics 24 as described in

the earlier system. The coupling of the plurality of laser consoles 22 into a

single optical fiber is achieved with a fiber coupler 42 as is known in the art.

Other known mechanisms for combining multiple light sources are available

and may be used to replace the fiber coupler described herein.

[Para 1161 In this system 20' the multiple light sources 22 follow a similar

path as described in the earlier system 20, i.e., collimated, diffracted,

recollimated, and directed to the projector device and/or tissue. However, the

diffractive element functions differently than described earlier depending upon

the wavelength of light passing through, which results in a slightly varying

pattern. The variation is linear with the wavelength of the light source being

diffracted. In general, the difference in the diffraction angles is small enough

that the different, overlapping patterns may be directed along the same optical

path through the projector device 26 to the tissue for treatment.

[Para 117] Since the resulting pattern will vary slightly for each wavelength, a

sequential offsetting to achieve complete coverage will be different for each

wavelength. This sequential offsetting can be accomplished in two modes. In the first mode, all wavelengths of light are applied simultaneously without identical coverage. An offsetting steering pattern to achieve complete coverage for one of the multiple wavelengths is used. Thus, while the light of the selected wavelength achieves complete coverage of the tissue, the application of the other wavelengths achieves either incomplete or overlapping coverage of the tissue. The second mode sequentially applies each light source of a varying wavelength with the proper steering pattern to achieve complete coverage of the tissue for that particular wavelength. This mode excludes the possibility of simultaneous treatment using multiple wavelengths, but allows the optical method to achieve identical coverage for each wavelength. This avoids either incomplete or overlapping coverage for any of the optical wavelengths.

[Para 118] These modes may also be mixed and matched. For example, two

wavelengths may be applied simultaneously with one wavelength achieving

complete coverage and the other achieving incomplete or overlapping coverage,

followed by a third wavelength applied sequentially and achieving complete

coverage.

[Para 119] FIGURE 19 illustrates diagrammatically yet another alternate

embodiment of the inventive system 20". This system 20" is configured

generally the same as the system 20 depicted in FIG. 11. The main difference

resides in the inclusion of multiple pattern-generating subassembly channels

tuned to a specific wavelength of the light source. Multiple laser consoles 22

are arranged in parallel with each one leading directly into its own laser

projector optics 24. The laser projector optics of each channel 44a, 44b, 44c comprise a collimator 32, mask or diffraction grating 34 and recollimators 38,

40 as described in connection with FIG. 12 above - the entire set of optics

tuned for the specific wavelength generated by the corresponding laser console

22. The output from each set of optics 24 is then directed to a beam splitter

46 for combination with the other wavelengths. It is known by those skilled in

the art that a beam splitter used in reverse can be used to combine multiple

beams of light into a single output. The combined channel output from the

final beam splitter 46c is then directed through the projector device 26.

[Para 120] In this system 20" the optical elements for each channel are tuned

to produce the exact specified pattern for that channel's wavelength.

Consequently, when all channels are combined and properly aligned a single

steering pattern may be used to achieve complete coverage of the tissue for all

wavelengths. The system 20" may use as many channels 44a, 44b, 44c, etc.

and beam splitters 46a, 46b, 46c, etc. as there are wavelengths of light being

used in the treatment.

[Para 121] Implementation of the system 20" may take advantage of different

symmetries to reduce the number of alignment constraints. For example, the

proposed grid patterns are periodic in two dimensions and steered in two

dimensions to achieve complete coverage. As a result, if the patterns for each

channel are identical as specified, the actual pattern of each channel would not

need to be aligned for the same steering pattern to achieve complete coverage

for all wavelengths. Each channel would only need to be aligned optically to

achieve an efficient combination.

[Para 122] In system 20", each channel begins with a light source 22, which

could be from an optical fiber as in other embodiments of the pattern

generating subassembly. This light source 22 is directed to the optical

assembly 24 for collimation, diffraction, recollimation and directed into the

beam splitter which combines the channel with the main output.

[Para 123] It will be understood that the laser light generating systems

illustrated in FIGS. 11-19 are exemplary. Other devices and systems can be

utilized to generate a source of SDM light which can be operably passed

through to a projector device.

[Para 124] The proposed treatment with a train of electromagnetic pulses has

two major advantages over earlier treatments that incorporate a single short or

sustained (long) pulse. First, the short (preferably subsecond) individual pulses

in the train activate cellular reset mechanisms like HSP activation with larger

reaction rate constants than those operating at longer (minute or hour) time

scales. Secondly, the repeated pulses in the treatment provide large thermal

spikes (on the order of 10,000) that allow the cell's repair system to more

rapidly surmount the activation energy barrier that separates a dysfunctional

cellular state from the desired functional state. The net result is a "lowered

therapeutic threshold" in the sense that a lower applied average power and total

applied energy can be used to achieve the desired treatment goal.

[Para 125] Power limitations in current micropulsed diode lasers require fairly

long exposure duration. The longer the exposure, the more important the

center-spot heat dissipating ability toward the unexposed tissue at the margins of the laser spot. Thus, the micropulsed laser light beam of an 810 nm diode laser should have an exposure envelope duration of 500 milliseconds or less, and preferably approximately 300 milliseconds. Of course, if micropulsed diode lasers become more powerful, the exposure duration should be lessened accordingly.

[Para 126] Aside from power limitations, another parameter of the present

invention is the duty cycle, or the frequency of the train of micropulses, or the

length of the thermal relaxation time between consecutive pulses. It has been

found that the use of a 10% duty cycle or higher adjusted to deliver micropulsed

laser at similar irradiance at similar MPE levels significantly increase the risk of

lethal cell injury. However, duty cycles of less than 10%, and preferably 5% or

less demonstrate adequate thermal rise and treatment at the level of theMPE

cell to stimulate a biological response, but remain below the level expected to

produce lethal cell injury. The lower the duty cycle, however, the exposure

envelope duration increases, and in some instances can exceed 500

milliseconds.

[Para 127] Each micropulse lasts a fraction of a millisecond, typically between

50 microseconds to 100 microseconds in duration. Thus, for the exposure

envelope duration of 300-500 milliseconds, and at a duty cycle of less than 5%,

there is a significant amount of wasted time between micropulses to allow the

thermal relaxation time between consecutive pulses. Typically, a delay of

between 1 and 3 milliseconds, and preferably approximately 2 milliseconds, of

thermal relaxation time is needed between consecutive pulses. For adequate treatment, the cells are typically exposed or hit between 50-200 times, and preferably between 75-150 at each location, and with the 1-3 milliseconds of relaxation or interval time, the total time in accordance with the embodiments described above to treat a given area which is being exposed to the laser spots is usually less than one second, such as between 100 milliseconds and 600 milliseconds on average. The thermal relaxation time is required so as not to overheat the cells within that location or spot and so as to prevent the cells from being damaged or destroyed. While time periods of 100-600 milliseconds do not seem long, given the small size of the laser spots and the need to treat a relatively large area of the target tissue, treating the entire target tissue take a significant amount of time, particularly for a patient who is undergoing treatment.

[Para 128] Accordingly, the present invention may utilize the interval between

consecutive applications to the same location to apply energy to a second

treatment area, or additional areas, of the target tissue that is spaced apart

from the first treatment area. The pulsed energy is returned to the first

treatment location, or previous treatment locations, within the predetermined

interval of time so as to provide sufficient thermal relaxation time between

consecutive pulses, yet also sufficiently treat the cells in those locations or

areas properly by sufficiently increasing the temperature of those cells over

time by repeatedly applying the energy to that location in order to achieve the

desired therapeutic benefits of the invention.

[Para 129] It is important to return to a previously treated location within a

predetermined amount of time to allow the area to cool down sufficiently

during that time, but also to treat it within the necessary window of time. In

the case of the light pulsed energy applications, the light is returned to the

previously treated location within multi-milliseconds, such as one to three

milliseconds, and preferably approximately two milliseconds. One cannot wait

one or two seconds and then return to a previously treated area that has not yet

received the full treatment necessary, as the treatment will not be as effective

or perhaps not effective at all. However, during that interval of time, typically

approximately 2 milliseconds, at least one other area, and typically multiple

areas, can be treated with a laser light application as the laser light pulses are

typically 50 seconds to 100 microseconds in duration. This is referred to

herein as microshifting. The number of additional areas which can be treated is

limited only by the micopulse duration and the ability to controllably move the

light beams from one area to another.

[Para 1301 Currently, approximately four additional areas which are

sufficiently spaced apart from one another can be treated during the thermal

relaxation intervals beginning with a first treatment area. Thus, multiple areas

can be treated, at least partially, during the 200-500 millisecond exposure

envelope for the first area. Thus, in a single interval of time, instead of only

100 simultaneous light spots being applied to a treatment area, approximately

500 light spots can be applied during that interval of time in different treatment

areas. This would be the case, for example, for a laser light beam having a wavelength of 810 nm. For shorter wavelengths, such as 572 nm, even a greater number of individual locations can be exposed to the laser beams to create light spots. Thus, instead of a maximum of approximately 400 simultaneous spots, approximately 2,000 spots could be covered during the interval between micropulse treatments to a given area or location. Typically each location has between 50-200, and more typically between 75-150, light applications applied thereto over the course of the exposure envelope duration

(typically 200-500 milliseconds) to achieve the desired treatment. In

accordance with an embodiment of the present invention, the light would be

reapplied to previously treated areas in sequence during the relaxation time

intervals for each area or location. This would occur repeatedly until a

predetermined number of laser light applications to each area to be treated

have been achieved.

[Para 1311 The pulsed energy could be reapplied to a previously treated area

in sequence during the relaxation time intervals for each area or location until a

desired number of applications has been achieved to each treatment area. The

treatment areas must be separated by at least a predetermined minimum

distance to enable thermal relaxation and heat dissipation and avoid thermal

tissue damage. The pulsed energy and application parameters are selected so

as to raise the target tissue temperature up to 11° C, such as between

approximately 6°-11 C, during application of the pulsed energy source to the

target tissue to achieve a therapeutic effect, such as by stimulating HSP

production within the cells. However, the cells of the target tissue must be given a period of time to dissipate the heat such that the average temperature rise of the tissue over several minutes is maintained at or below a predetermined level, 1° C or less over several minutes, so as not to permanently damage the target tissue.

[Para 132] This is diagrammatically illustrated in FIGS. 20A-20D. FIG. 20A

illustrates with solid circles a first area having energy beams, such as laser light

beams, applied thereto as a first application. The beams are controllably offset

or microshifted to a second exposure area, followed by a third exposure area

and a fourth exposure area, as illustrated in FIG. 20B, until the locations in the

first exposure area need to be re-treated by having beams applied thereto

again within the thermal relaxation time interval. The locations within the first

exposure area would then have energy beams reapplied thereto, as illustrated

in FIG. 20C. Secondary or subsequent exposures would occur in each exposure

area, as illustrated in FIG. 20D by the increasingly shaded dots or circles until

the desired number of exposures or hits or applications of energy to the target

tissue area has been achieved to therapeutically treat these areas,

diagrammatically illustrated by the blackened circles in exposure area 1 in FIG.

20D. When a first or previous exposure area has been completed treated, this

enables the system to add an additional exposure area, which process is

repeated until the entire area to be treated has been fully treated. It should be

understood that the use of solid circles, broken line circles, partially shaded

circles, and fully shaded circles are for explanatory and illustration purposes

only, as in fact the exposure of the energy or laser light in accordance with the present invention is invisible and non-detectable to both the human eye as well as known detection devices and techniques.

[Para 133] Adjacent exposure areas must be separated by at least a

predetermined minimum distance to avoid thermal tissue damage. Such

distance is at least 0.5 diameter away from the immediately preceding treated

location or area, and more preferably between 1-2 diameters away. Such

spacing relates to the actually treated locations in a previous exposure area. It

is contemplated by the present invention that a relatively large area may

actually include multiple exposure areas therein which are offset in a different

manner than that illustrated in FIG. 20. For example, the exposure areas could

comprise the thin lines illustrated in FIGS. 16 and 17, which would be

repeatedly exposed in sequence until all of the necessary areas were fully

exposed and treated. In accordance with the present invention, the time

required to treat that area to be treated is significantly reduced, such as by a

factor of 4 or 5 times, such that a single treatment session takes much less

time for the medical provider and the patient need not be in discomfort for as

long of a period of time.

[Para 134] In accordance with this embodiment of the invention of applying

one or more treatment beams at once, and moving the treatment beams to a

series of new locations, then bringing the beams back to re-treat the same

location or area repeatedly has been found to also require less power compared

to the methodology of keeping the beams in the same locations or area during

the entire exposure envelope duration. With reference to FIGS. 21-23, there is a linear relationship between the pulse length and the power necessary, but there is a logarithmic relationship between the heat generated.

[Para 135] With reference to FIG. 21, a graph is provided wherein the x-axis

represents the Log of the average power in watts of a laser and the y-axis

represents the treatment time, in seconds. The lower curve is for panmacular

treatment and the upper curve is for panretinal treatment. This would be for a

laser light beam having a micropulse time of 50 microseconds, a period of 2

milliseconds of time between pulses, and duration of train on a spot of 300

milliseconds. The areas of each retinal spot are 100 microns, and the laser

power for these 100 micron retinal spots is 0.74 watts. The panmacular area is

0.552, requiring 7,000 panmacular spots total, and the panretinal area is 3.302,

requiring 42,000 laser spots for full coverage. Each RPE spot requires a

minimum energy in order for its reset mechanism to be adequately activated, in

accordance with the present invention, namely, 38.85 joules for panmacular

and 233.1 joules for panretinal. As would be expected, the shorter the

treatment time, the larger the required average power. However, there is an

upper limit on the allowable average power, which limits how short the

treatment time can be.

[Para 1361 As mentioned above, there are not only power constraints with

respect to the laser light available and used, but also the amount of power that

can be applied to the eye without damaging eye tissue. For example,

temperature rise in the lens of the eye is limited, such as approximately 40 C so

as not to overheat and damage the lens, such as causing cataracts. Thus, an average power of 7.52 watts could elevate the lens temperature to approximately 40 C. This limitation in power increases the minimum treatment time.

[Para 1371 However, with reference to FIG. 22, the total power per pulse

required is less in the microshift case of repeatedly and sequentially moving the

laser spots and returning to prior treated locations, so that the total energy

delivered and the total average power during the treatment time is the same.

FIGS. 22 and 23 show how the total power depends on treatment time. This is

displayed in FIG. 22 for panmacular treatment, and in FIG. 23 for panretinal

treatment. The upper, solid line or curve represents the embodiment where

there are no microshifts taking advantage of the thermal relaxation time

interval, such as described and illustrated in FIG. 15, whereas the lower dashed

line represents the situation for such microshifts, as described and illustrated in

FIG. 20. FIGS. 21 and 22 show that for a given treatment time, the peak total

power is less with microshifts than without microshifts. This means that less

power is required for a given treatment time using the microshifting

embodiment of the present invention. Alternatively, the allowable peak power

can be advantageously used, reducing the overall treatment time.

[Para 1381 Thus, in accordance with FIGS. 21-23, a log power of 1.0 (10 watts)

would require a total treatment time of 20 seconds using the microshifting

embodiment of the present invention, as described herein. It would take more

than 2 minutes of time without the microshifts, and instead leaving the

micropulsed light beams in the same location or area during the entire treatment envelope duration. There is a minimum treatment time according to the wattage. However, this treatment time with microshifting is much less than without microshifting. As the laser power required is much less with the microshifting, it is possible to increase the power in some instances in order to reduce the treatment time for a given desired retinal treatment area. The product of the treatment time and the average power is fixed for a given treatment area in order to achieve the therapeutic treatment in accordance with the present invention. This could be implemented, for example, by applying a higher number of therapeutic laser light beams or spots simultaneously at a reduced power. Of course, since the parameters of the laser light are selected to be therapeutically effective yet not destructive or permanently damaging to the cells, no guidance or tracking beams are required, only the treatment beams as all areas can be treated in accordance with the present invention.

[Para 1391 Although the present invention is described for use in connection

with a micropulsed laser, theoretically a continuous wave laser could potentially

be used instead of a micropulsed laser. However, with the continuous wave

laser, there is concern of overheating as the laser is moved from location to

location in that the laser does not stop and there could be heat leakage and

overheating between treatment areas. Thus, while it is theoretically possible to

use a continuous wave laser, in practice it is not ideal and the micropulsed laser

is preferred.

[Para 140] While the information provided in connection with graphs 21-23 is

derived from observations and calculations of light beams as the energy source applied to retinal eye tissue, it is believed that applying such pulsed light to other tissue will achieve similar results in that moving the treatment beams to a series of new locations, then bringing the beams back to re-treat the same location or area repeatedly will not only save time but also require less power compared to the methodology of keeping the beams in the same location or area during the entire exposure envelope duration.

[Para 141] In accordance with the microshifting technique described above,

the shifting or steering of the pattern of light beams may be done by use of an

optical scanning mechanism, such as that illustrated and described in

connection with FIGS. 13 and 14.

[Para 142] Steering for energy sources may be done by use of multiple

sources which provide an "array". The basic idea for steering the illumination

radiation pattern of an array is constructive (and destructive) interference

between the radiation from the individual members of the array of sources.

[Para 143] As mentioned above, the controlled manner of applying energy to

the target tissue is intended to raise the temperature of the target tissue to

therapeutically treat the target tissue without destroying or permanently

damaging the target tissue. It is believed that such heating activates HSPs and

that the thermally activated HSPs work to reset the diseased tissue to a healthy

condition, such as by removing and/or repairing damaged proteins. It is

believed by the inventors that maximizing such HSP activation improves the

therapeutic effect on the targeted tissue. As such, understanding the behavior

and activation of HSPs and HSP system species, their generation and activation, temperature ranges for activating HSPs and time frames of the HSP activation or generation and deactivation can be utilized to optimize the heat treatment of the biological target tissue.

[Para 144] As mentioned above, the target tissue is heated by the pulsed

energy for a short period of time, such as ten seconds or less, and typically less

than one second, such as between 100 milliseconds and 600 milliseconds. The

time that the energy is actually applied to the target tissue is typically much

less than this in order to provide intervals of time for heat relaxation so that the

target tissue does not overheat and become damaged or destroyed. For

example, as mentioned above, laser light pulses may last on the order of

microseconds with several milliseconds of intervals of relaxed time.

[Para 145] Thus, understanding the sub-second behaviors of HSPs can be

important to the present invention. The thermal activation of the HSPs in SDM

is typically described by an associated Arrhenius integral,

Q = fdt A exp[-E/kBT(t)] [1]

where the integral is over the treatment time and

A is the Arrhenius rate constant for HSP activation

E is the activation energy

T(t) is the temperature of the thin RPE layer, including the laser-induced

temperature rise

[Para 146] The laser-induced temperature rise - and therefore the activation

Arrhenius integral -- depends on both the treatment parameters (e.g., laser

power, duty cycle, total train duration) and on the RPE properties (e.g., absorption coefficients, density of HSPs). It has been found clinically that effective SDM treatment is obtained when the Arrhenius integrals is of the order of unity.

[Para 147] The Arrhenius integral formalism only takes into account a forward

reaction, i.e. only the HSP activation reaction): It does not take into account any

reverse reactions in which activated HSPs are returned to their inactivated

states. For the typical subsecond durations of SDM treatments, this appears to

be quite adequate. However, for longer periods of time (e.g. a minute or

longer), this formalism is not a good approximation: At these longer times, a

whole series of reactions occurs resulting in much smaller effective HSP

activation rates. This is the case during the proposed minute or so intervals

between SDM applications in the present invention disclosure.

[Para 148] In the published literature, the production and destruction of heat

shock proteins (HSPs) in cells over longer durations is usually described by a

collection of 9-13 simultaneous mass-balance differential equations that

describe the behavior of the various molecular species involved in the life cycle

of an HSP molecule. These simultaneous equations are usually solved by

computer to show the behavior in time of the HSPs and the other species after

the temperature has been suddenly raised.

[Para 149] These equations are all conservation equations based on the

reactions of the various molecular species involved in the activity of HSPs.

To describe the behavior of the HSPs in the minute or so intervals between

repeated applications of SDM, we shall use the equations described in M.

Rybinski, Z.Szymanska, S. Lasota, A. Gambin (2013) Modeling the efficacy of

hyperthermia treatment. Journal of the Royal Society Interface 10, No. 88,

20130527 (Rybinski et al (2013)). The species considered in Rybinski et al

(2013) are shown in Table 8.

[Para 150] Table 8. HSP system species in Rybinski et al (2013) description:

HSP ubiquitous heat shock protein of molecular weight 70 Da (in

free, activated state)

HSF heat shock (transcription) factor that has no DNA binding

capability

HSF 3 (trimer) heat shock factor capable of binding to DNA, formed

from HSF

HSE heat shock element, a DNA site that initiates transcription of

HSP when bound to HSF 3

mRNA messenger RNA molecule for producing HSP

S substrate for HSP binding: a damaged protein

P properly folded protein

HSP.HSF a complex of HSP bound to HSF (unactivated HSPs)

HSF 3 .HSE a complex of HSF 3 bound to HSE, that induces transcription

and the creation of a new HSP mRNA molecule

HSP.S a complex of HSP attached to damaged protein (HSP actively

repairing the protein)

[Para 151] The coupled simultaneous mass conservation equations for these

10 species are summarized below as eqs. [2]-[l1]: d[HSP]/dt = (11+kio)[HSPS] +1 2 [HSPHSF] +k 4 [mRNA]

- ki[S][HSP]-k2 [HSP][HSF]-1 3 [HSP][HSF 3 ] - kg[HSP] [2]

d{HSF]/dt = 1 2 [HSPHSF]+ 21 3 [HSP][HSF 3] + k[HSPHSF][S]

-k 2 [HSP][HSF] - 3k 3[HSF] 3 - 16[HSPS][HSF] [3]

d[S]I/dt = kii{[P] +l1[HSPS] + 16 [SPS][HSF] - ki[S][HSP] - k6 [HSPHSF] [S]

[4]

d[HSPHSF]/dt = k 2[HSP][HSF] + 1 6 [HSPS][HSF] + 1 3 [HSP][HSF 3]

- 1 2[HSPHSF] - k 6[HSPHSF] [S] [5]

d[HSPS]/dt= ki[S][HSP] + k6 [HSPHSF] [S] - (11+kio)[HSPS] - 16 [HSPS][HSF]

[6]

d[HSF 3]/dt= k3 [HSF] 3 + 1 7[HSF 3][HSE] - 1 3 [HSP][HSF 3] - k7 [HSF 3][HSE] [7]

d[HSE]/dt= 1 7[HSF 3][HSE] - k7 [HSF 3][HSE] [8]

d[HSF 3HSE]/dt = k7 [HSF 3][HSE] - 1 7 [HSF 3][HSE] [9]

d[mRNA]/dt = k 8 [HSF 3HSE] - k 5 [mRNA] [10]

d[P]/dt = klo[HSPS] - ki[P] [11]

[Para 152] In these expressions, [] denotes the cellular concentration of the

quantity inside the bracket. For Rybinski et al (2013), the initial concentrations

at the equilibrium temperature of 310K are given in Table 9.

[Para 153] Table 9. Initial values of species at 31OK for a typical cell in

arbitrary units [Rybinski et al (2013)] . The arbitrary units are chosen by

Rybinski et al for computational convenience: to make the quantities of interest

in the range of 0.01-10.

[HSP(0)] 0.308649

[HSF(0)] 0.150836

[S(0)] 0.113457

[HSPHSF(0)] 2.58799

[HSPS(0)] 1.12631

[HSF 3(0)] 0.0444747

[HSE(0)] 0.957419

[HSF 3 HSE(0)] 0.0425809

[mRNA(0)] 0.114641

[P(0)] 8.76023

[Para 1541 The Rybinski et al (2013) rate constants are shown in Table 10.

[Para 155] Table 10. Rybinski et al (2013) rate constants giving rates in min-1

for the arbitrary concentration units of the previous table.

11= 0.0175

ki= 1.47

12= 0.0175

k2= 1.47

13= 0.020125

k3 = 0.0805

k4 = 0.1225

k 5 = 0.0455

k6 = 0.0805

16= 0.00126

k= 0.1225

17= 0.1225

k8 = 0.1225

k= 0.0455

kio = 0.049

kn = 0.00563271

[Para 156] The initial concentration values of Table 9 and the rate constants of

Table 10 were determined by Rybinski et al (2013) to correspond to

experimental data on overall HSP system behavior when the temperature was

increased on the order of 5° C for several (e.g. 350) minutes.

[Para 157] Note that the initial concentration of HSPs is 100 x

0.308649/(8.76023+0.113457+1.12631)} = 3.09% of the total number of

proteins present in the cell.

[Para 158] Although the rate constants of Table 10 are used by Rybinski et al

for T = 310+5+ 315K, it is likely that very similar rate constants exist at other

temperatures. In this connection, the qualitative behavior of the simulations is

similar for a large range of parameters. For convenience, we shall assume that

the values of the rate constants in Table 10 are a good approximation for the

values at the equilibrium temperature of T = 310K.

[Para 159] The behavior of the different components in the Rybinski et al cell

is displayed in FIGS. 24A-24Bfor 350 minutes for the situation where the

temperature is suddenly increased 5K at t=0 from an ambient 310K.

[Para 160] With continuing reference to FIGS. 24A-24B, the behavior of HSP

cellular system components during 350 minutes following a sudden increase in

temperature from 37 C to 420 C is shown.

[Para 161] Here, the concentrations of the components are presented in

computationally convenient arbitrary units. S denotes denatured or damaged

proteins that are as yet unaffected by HSPs; HSP denotes free (activated) heat

shock proteins; HSP:S denotes activated HSPs that are attached to the damaged

proteins and performing repair; HSP:HSF denotes (inactive) HSPs that are

attached to heat shock factor monomers; HSF denotes a monomer of heat

shock factor; HSF 3 denotes a trimer of heat shock factor that can penetrate the

nuclear membrane to interact with a heat shock element on the DNA molecule;

HSE:HSF 3 denotes a trimer of heat shock factor attached to a heat shock

element on the DNA molecule that initiates transcription of a new mRNA

molecule; mRNA denotes the messenger RNA molecule that results from the

HSE:HSF 3, and that leads to the production of a new (activated) HSP molecule in

the cell's cytoplasm.

[Para 162] FIGURE 24 shows that initially the concentration of activated HSPs is

the result of release of HSPs sequestered in the molecules HSPHSF in the

cytoplasm, with the creation of new HSPs from the cell nucleus via mRNA not

occurring until 60 minutes after the temperature rise occurs. FIG. 24 also

shows that the activated HSPs are very rapidly attached to damaged proteins to

begin their repair work. For the cell depicted, the sudden rise in temperature

also results in a temporary rise in damaged protein concentration, with the peak in the damaged protein concentration occurring about 30 minutes after the temperature increase.

[Para 163] FIGURE 24 shows what the Rybinski et al equations predict for the

variation of the 10 different species over a period of 350 minutes. However,

the present invention is concerned with SDM application is on the variation of

the species over the much shorter O(minute) interval between two applications

of SDM at any single retinal locus. It will be understood that the preferred

embodiment of SDM in the form of laser light treatment is analyzed and

described, but it is applicable to other sources of energy as well.

[Para 164] With reference now to FIGS. 25A-25H, the behavior of HSP cellular

system components during the first minute following a sudden increase in

temperature from 37° C to 42° C using the Rybinski et al. (2013) equations with

the initial values and rate constants of Tables 9 and 10 are shown. The

abscissa denotes time in minutes, and the ordinate shows concentration in the

same arbitrary units as in FIG. 25.

[Para 165] FIGURE 25 shows that the nuclear source of HSPs plays virtually no

role during a 1 minute period, and that the main source of new HSPs in the

cytoplasm arises from the release of sequestered HSPs from the reservoir of

HSPHSF molecules. It also shows that a good fraction of the newly activated

HSPs attach themselves to damaged proteins to begin the repair process.

[Para 166] The initial concentrations in Table 9 are not the equilibrium values

of the species, i.e. they do not give d[.. .]/dt = 0, as evidenced by the curves in

FIGS. 24 and 25. The equilibrium values that give d[...]/dt = 0 corresponding

to the rate constants of Table 10 are found to be those listed in Table 11.

[Para 167] Table 11. Equilibrium values of species in arbitrary units [Rybinski

et al (2013)] corresponding to the rate constants of Table 10. The arbitrary

units are those chosen by Rybinski et al for computational convenience: to

make the quantities of interest in the range of 0.01-10.

[HSP(equil)] 0.315343

[HSF(equil)] 0.255145

[S(equil )] 0.542375

[HSPHSF(equil)] 1.982248

[HSPS(equil)] 5.05777

[HSF3(equil)] 0.210688

[HSE(equil)] 0.206488

[HSF3HSE(equil)] 0.643504

[mRNA(equil)] 0.1171274

[P(equil)] 4.39986

[Para 1681 Note that the equilibrium concentration of HSPs is 100 x

{0.315343/(4.39986+5.05777+0.542375 )} = 3.15% of the total number of

proteins present in the cell. This is comparable, but less than the anticipated

5% - 10% total number of proteins found by other researchers. However, we

have not attempted to adjust percentage upwards expecting that the general

behavior will not be appreciably changed as indicated by other researchers.

[Para 169] The inventors have found that a first treatment to the target tissue

may be performed by repeatedly applying the pulsed energy (e.g., SDM) to the

target tissue over a period of time so as to controllably raise a temperature of

the target tissue to therapeutically treat the target tissue without destroying or

permanently damaging the target tissue. A "treatment" comprises the total

number of applications of the pulsed energy to the target tissue over a given

period of time, such as dozens or even hundreds of light or other energy

applications to the target tissue over a short period of time, such as a period of

less than ten seconds, and more typically a period of less than one second,

such as 100 milliseconds to 600 milliseconds. This "treatment" controllably

raises the temperature of the target tissue to activate the heat shock proteins

and related components.

[Para 170] What has been found, however, is that if the application of the

pulsed energy to the target tissue is halted for an interval of time, such as an

interval of time that exceeds the first period of time comprising the "first

treatment", which may comprise several seconds to several minutes, such as

three seconds to three minutes or more preferably ten seconds to ninety

seconds, and then a second treatment is performed on the target tissue after

the interval of time within a single treatment session or office visit, wherein the

second treatment also entails repeatedly reapplying the pulsed energy to the

target tissue so as to controllably raise the temperature of the target tissue to

therapeutically treat the target tissue without destroying or permanently

damaging the target tissue, the amount of activated HSPs and related components in the cells of the target tissue is increased resulting in a more effective overall treatment of the biological tissue. In other words, the first treatment creates a level of heat shock protein activation of the target tissue, and the second treatment increases the level of heat shock protein activation in the target tissue above the level due to the first treatment. Thus, performing multiple treatments to the target tissue of the patient within a single treatment session or office visit enhances the overall treatment of the biological tissue so long as the second or additional treatments are performed after an interval of time which does not exceed several minute but which is of sufficient length so as to allow temperature relaxation so as not to damage or destroy the target tissue.

[Para 171] This technique may be referred to herein as "stair-stepping" in that

the levels of activated HSP production increase with the subsequent treatment

or treatments within the same office visit treatment session. This "stair

stepping" technique may be described by a combination of the Arrhenius

integral approach for subsecond phenomena with the Rybinski et al. (2013)

treatment of intervals between repeated subsecond applications of the SDM or

other pulsed energy.

[Para 172] For the proposed stair-stepping SDM (repetitive SDM applications)

proposed in this invention disclosure, there are some important differences

from the situation depicted in Figure 24:

• SDM can be applied prophylactically to a healthy cell, but oftentimes SDM

will be applied to a diseased cell. In that case, the initial concentration of damaged proteins [S(0)] can be larger than given in Table 11. We shall not attempt to account for this, assuming that the qualitative behavior will not be changed.

• The duration of a single SDM application is only subseconds, rather than

the minutes shown in Figure 24. The Rybinski et al rate constants are

much smaller than the Arrhenius constants: the latter give Arrhenius

integrals of the order of unity for subsecond durations, whereas the

Rybinski et al rate constants are too small to do that. This is an example

of the different effective rate constants that exist when the time scales of

interest are different: The Rybinski et al rate constants apply to

phenomena occurring over minutes, whereas the Arrhenius rate

constants apply to subsecond phenomena.

[Para 173] Accordingly, to analyze what happens in the proposed stair

stepping SDM technique for improving the efficacy of SDM, we shall combine

the Arrhenius integral treatment appropriate for the subsecond phenomena

with the Rybinski et al (2013) treatment appropriate for the phenomena

occurring over the order of a minute interval between repeated SDM

applications:

• SDM subsecond application described by Arrhenius integral formalism

• Interval of O(minute) between SDM applications described by Rybinski et

al (2013) equations

[Para 174] Specifically, we consider two successive applications of SDM, each

SDM micropulse train having a subsecond duration.

* For the short subsecond time scale, we assume that the unactivated HSP's

that are the source of the activated (free) HSP's are all contained in the

HSPHSF molecules in the cytoplasm. Accordingly, the first SDM

application is taken to reduce the cytoplasmic reservoir of unactivated

HSPs in the initial HSPHSF molecule population from

[HSPHSF(equil)] to [HSPHSF(equil)]exp[-Q]

, • and to increase the initial HSP molecular population from

[HSP(equil)] to [HSP(equil)] + [HSPHSF(equil)](1-exp[-Q])

• as well as to increase the initial HSF molecular population from

[HSF(equil)] to [HSF(equil)] + [HSPHSF(equil)](1-exp[-Q])

• The equilibrium concentrations of all of the other species will be assumed

to remain the same after the first SDM application

• The Rybinski et al equations are then used to calculate what happens to

[HSP] and [HSPHSF] in the interval Xt = O(minute) between the first SDM

application and the second SDM application, with the initial values of HSP,

HSF and HSPHSF after the first SDM application taken to be

[HSP(SDM1)] = [HSP(equil)] + [HSPHSF(equil)](1-exp[-Q])

[HSF(SDM1)] = [HSF(equil)] + [HSPHSF(equil)](1-exp[-Q])

and

[HSPHSF(SDM1)] = [HSPHSF(equil)]exp[-Q]

• For the second application of SDM after the interval Xt, the values of

[HSP], [HSF] and {HSPHSF] after the SDM will be taken to be

[HSP(SDM2)] = [HSP(t)] + [HSPHSF(t)](1-exp[-Q])

[HSF(SDM2)] = [HSF(t)] + [HSPHSF(t)](1-exp[-Q])

and

[HSPHSF(SDM2)] = [HSPHSF(Xt)]exp[-Q]

where [HSP(t)], [HSF(t)], and [HSPHSF(t)] are the values determined

from the Rybinski et al (2013) equations at the time Xt.

Our present interest is in comparing [HSP[SDM2)] with [HSP[SDM1)], to

see if the repeated application of SDM at an interval Xt following the first

application of SDM has resulted in more activated (free) HSP's in the

cytoplasm. The ratio $(Xt, Q) = [HSP(SDM2)]/ [HSP(SDM1)]

= {[{[HSP(Xt)] + [HSPHSF(t)](1-exp[-Q])}/{ [HSP(0)] + [HSPHSF(0)](1

exp[-Q])}

provides a direct measure of the improvement in the degree of HSP

activation for a repeated application of SDM after an interval Xt from the first

SDM application.

[Para 175] The HSP and HSPHSF concentrations can vary quite a bit in the

interval Xt between SDM applications.

[Para 176] FIGURES 26A and 26B illustrate the variation in the activated

concentrations [HSP] and the unactivated HSP in the cytoplasmic reservoir

[HSPHSF] during an interval Xt = 1 minute between SDM applications when the

SDM Arrhenius integral Q = 1 and the equilibrium concentrations are as given

in Table 11.

[Para 177] Although only a single repetition (one-step) is treated here, it is

apparent that the procedure could be repeated to provide a multiple stair stepping events as a means of improving the efficacy of SDM, or other therapeutic method involving activation of tissue HSPs.

[Para 178] Effects of varying the magnitude of the Arrhenius integral 0 and

interval t between two distinct treatments separated by an interval of time are

shown by the following examples and results.

[Para 179] Nine examples generated with the procedure described above are

presented in the following. All of the examples are of a treatment consisting of

two SDM treatments, with the second occurring at a time Xt following the first,

and they explore:

• The effect of different magnitude Arrhenius integrals Q in the SDM

treatments [Three different Q's are considered: Q = 0.2,0.5 and 1.0]

* The impact of varying the interval Xt between the two SDM treatments

[Three different t's are considered: Xt = 15 sec., 30 sec., and 60 sec.

[Para 180] As indicated above, the activation Arrhenius integral 0 depends on

both the treatment parameters (e.g., laser power, duty cycle, total train

duration) and on the RPE properties (e.g., absorption coefficients, density of

HSPs).

[Para 181] Table 12 below shows the effect of different Q (D = 0.2, 0.5, 1) on

the HSP content of a cell when the interval between the two SDM treatments is

Xt = 1 minute . Here the cell is taken to have the Rybinski et al (2013)

equilibrium concentrations for the ten species involved, given in Table 11.

[Para 182] Table 12 shows four HSP concentrations (in the Rybinski et al

arbitrary units) each corresponding to four different times:

* Before the first SDM treatment: [HSP(equil)]

• Immediately after the first SDM application: [HSP(SDM1)]

• At the end of the intervalXt following the first SDM treatment: [HSP(Xt)]

• Immediately after the second SDM treatment at Xt: [HSP(SDM2)]

• Also shown is the improvement factor over a single treatment:$

=[HSP(SDM2)]/ [HSP(SDM1)]

[Para 183] Table 12. HSP concentrations at the four times just described in

the text: Effect of varying the SDM Q for two SDM applications on a cell when

the treatments are separated by Xt = 0.25 minutes = 15 seconds.

[HSP(equil)] [HSP(SDM1)] [HSP(Xt)] [HSP(SDM2)]

$ Q = 0.2 0.315 0.67 0.54 0.95 1.27

Q = 0.5 0.315 1.10 0.77 1.34 1.22

Q = 1.0 0.315 1.57 0.93 1.71 1.09

[Para 184] Table 13 is the same as Table 12, except that it is for an interval

between SDM treatments of Xt = 0.5 minutes = 30 seconds.

[Para 185] Table 13. HSP concentrations at the four times described in the

text: Effect of varying the SDM Q for two SDM treatments on a cell when the

treatments are separated by Xt = 0.5 minutes = 30 seconds.

[HSP(equil)] [HSP(SDM1)][HSP(Xt)] [HSP(SDM2)] $

Q = 0.2 0.315 0.67 0.44 0.77 1.14

Q = 0.5 0.315 1.10 0.58 1.18 1.08

Q = 1.0 0.315 1.57 0.67 1.59 1.01

[Para 186] Table 14 is the same as the Tables 12 and 13, except that the

treatments are separated by one minute, or sixty seconds.

[Para 187] Table 14. HSP concentrations at the four times just described in

the text: Effect of varying the SDM Q for two SDM treatments on a normal

(healthy) cell when the treatments are separated by Xt = 1 minute = 60

seconds.

[HSP(equil)] [HSP(SDM1)][HSP(Xt)] [HSP(SDM2)]

$ Q = 0.2 0.315 0.67 0.30 0.64 0.95

Q = 0.5 0.315 1.10 0.37 1.06 0.96

Q = 1.0 0.315 1.57 0.48 1.51 0.96

[Para 188] Tables 12-14 show that:

• The first treatment of SDM increases [HSP] by a large factor for all three

Q's, although the increase is larger the larger Q. Although not displayed

explicitly in the tables, the increase in [HSP] comes at the expense of the

cytoplasmic reservoir of sequestered (unactivated) HSP's:

[HSPHSF(SDM1)] is much smaller than [HSPHSF(equil)]

• [HSP]decreases appreciably in the interval Xt between the two SDM

treatments, with the decrease being larger the larger Xt is. (The decrease

in [HSP] is accompanied by an increase in both [HSPHSF] - as shown in

Figure 26 and in [HSPS] during the interval Xt - indicating a rapid

replenishment of the cytoplasmic reservoir of unactivated HSP's and a

rapid attachment of HSP's to the damaged proteins.)

* For t less than 60 seconds, there is an improvement in the number of

activated (free) HSP's in the cytoplasm for two SDM treatments rather

than a single treatment.

• The improvement increases as Xt becomes smaller.

• For t becoming as large as 60 seconds, however, the ratioB

=[HSP(SDM2)]/ [HSP(SDM1)] becomes less than unity, indicating no

improvement in two SDM treatments compared to a single SDM treatment

although this result can vary depending on energy source parameters and

tissue type that is treated.

• The improvement for t<60 seconds is larger the smaller the SDM

Arrhenius integral 0 is.

[Para 1891 The results for the improvement ratio B =[HSP(SDM2)]/ [HSP(SDM1)]

are summarized in Figure 27, where the improvement ratio B =[HSP(SDM2)]/

[HSP(SDM1)] vs. interval between SDM treatments t (in seconds) for three

values of the SDM Arrhenius integral Q, and for the three values of the interval

Xt = 15 sec, 30 sec, and 60 sec . The uppermost curve is for Q = 0.2; the

middle curve is for 0=0.5; and the bottom curve is for Q = 1.0. These results

are for the Rybinski et al (2013) rate constants of Table 10 and the equilibrium

species concentrations of Table 11.

[Para 190] It should be appreciated that results of Tables 12-14 and FIG. 27

are for the Rybinski et al. (2013) rate constants of Table 10 and the equilibrium

concentrations of Table 11. The actual concentrations and rate constants in a

cell may differ from these values, and thus the number results in Tables 12-14 and FIG. 27 should be taken as representative rather than absolute. However, they are not anticipated to be significantly different. Thus, performing multiple intra-sessional treatments on a single target tissue location or area, such as a single retinal locus, with the second and subsequent treatments following the first after an interval anywhere from three seconds to three minutes, and preferably ten seconds to ninety seconds, should increase the activation of

HSPs and related components and thus the efficacy of the overall treatment of

the target tissue. The resulting "stair-stepping" effect achieves incremental

increases in the number of heat shock proteins that are activated, enhancing

the therapeutic effect of the treatment. However, if the interval of time between

the first and subsequent treatments is too great, then the "stair-stepping"

effect is lessened or not achieved.

[Para 191] The technique of the present invention is especially useful when

the treatment parameters or tissue characteristics are such that the associated

Arrhenius integral for activation is low, and when the interval between repeated

applications is small, such as less than ninety seconds, and preferably less than

a minute. Accordingly, such multiple treatments must be performed within the

same treatment session, such as in a single office visit, where distinct

treatments can have a window of interval of time between them so as to achieve

the benefits of the technique of the present invention.

[Para 192] Although several embodiments have been described in detail for

purposes of illustration, various modifications may be made without departing from the scope and spirit of the invention. Accordingly, the invention is not to be limited, except as by the appended claims.

[Para 193] In the claims which follow and in the preceding description of the

invention, except where the context requires otherwise due to express

language or necessary implication, the word "comprise" or variations such as

"comprises" or "comprising" is used in an inclusive sense, namely, to specify the

presence of the stated features but not to preclude the presence or addition of

further features in various embodiments of the invention.

[Para 194] It is to be understood that, if any prior art publication is referred to

herein, such reference does not constitute an admission that the publication

forms a part of the common general knowledge in the art, in Australia or any

other country.

Claims

What is claimed is:

[Claim 1] A process for heat treating retinal tissue, comprising the steps of:

selecting a treatment radiation spot size having a diameter within a range

of between 10-700 microns;

selecting a total pulsed treatment radiation train duration within a range

of between 30-800 milliseconds;

generating pulsed treatment radiation comprising a plurality of light

beams having a wavelength between 570 nm and 1300 nm and an average

power selected in the range of between 1.0 to 37.5 watts; and

simultaneously applying the plurality of treatment light beams to retinal

tissue for a first period of time comprising 30-800 milliseconds such that a

plurality of spaced apart treatment radiation spots are formed on the retinal

tissue and the retinal tissue is heat stimulated sufficiently to create a

therapeutic effect without permanently damaging or destroying the tissue and

to stimulate heat shock protein activation in the tissue;

halting the application of the treatment radiation for an interval of time

comprising between 10 to 90 seconds; and

re-applying the treatment radiation to the tissue after the interval of time

within a single treatment session so as to controllably raise the temperature of

the tissue without destroying the tissue to increase the level of heat shock

protein activation in the tissue; wherein the average power of the treatment radiation is selected to be monotonically lower within its range when the treatment radiation spot size is selected to be smaller within its range and/or when the total pulsed treatment radiation train duration is selected to be higher within its range.
[Claim 2] The process of claim 1, wherein the tissue is heated to between six

and eleven degrees Celsius during the application of the treatment radiation to

the tissue, but the average temperature rise of the tissue over six minutes or

less is maintained at approximately one degree Celsius or less.
[Claim 31 The process of claim 1or claim 2, wherein the treatment radiation

spot size, total pulsed treatment radiation train duration and average power are

selected based on thermal properties of the retinal tissue being treated.
[Claim 4] The process of any one of the preceding claims, wherein the

treatment radiation is applied to at least a portion of the fovea of the eye.
[Claim 5] The process of any one of the preceding claims, wherein the

treatment radiation has a wavelength between 600 nm-1100 nm, an average

power of between 1.0 and 6.94 watts, and forms at least one treatment spot

having a diameter between 100-500 microns.
[Claim 6] The process of any one of the preceding claims, wherein during an

interval of time, comprising less than one second, between pulses of treatment

radiation applied to a first treatment area of the tissue, simultaneously applying

the treatment radiation beams to a second treatment area of the tissue

sufficiently spaced apart from the first treatment area of the tissue to avoid

thermal tissue damage of the target tissue and repeatedly simultaneously

applying, in an alternating manner during the same treatment session, the

treatment radiation beams to each of the first and second treatment areas of

the tissue until a predetermined number of applications to each of the first and

second treatment areas of the tissue has been achieved.
[Claim 7] The process of any one of the preceding claims, wherein the light

beams have a duty cycle between 2.5% and 5%.
[Claim 8] A process for heat treating retinal tissue, comprising the steps of:

generating a pulsed treatment radiation comprising a plurality of light

beams having a wavelength between 570 nm and 1300 nm and an average

power selected from a range of between 1.0 to 37.5 watts; and

simultaneously applying the treatment radiation light beams to retinal

tissue, including at least a portion of the fovea, such that a plurality of spaced

apart treatment spots each having a diameter selected from a range between

100-700 microns is formed on the retinal tissue and for a total pulsed train

duration selected from a range of between 30-800 milliseconds such that the retinal tissue is heated to between six and eleven degrees Celsius during the application of the treatment radiation to the retinal tissue while providing thermal relaxation periods between pulses such that the average temperature rise of the tissue over six minutes or less is maintained at approximately one degree Celsius or less, whereby a therapeutic effect is created without permanently damaging or destroying the tissue; applying the treatment radiation to the tissue for a first period of time comprising the total pulsed train duration of between 30-800 milliseconds to stimulate heat shock protein activation in the tissue; halting the application of the treatment radiation for an interval of time that exceeds the first period of time comprising 10 to 90 seconds; and re-applying the treatment radiation to the tissue after the interval of time within a single treatment session so as to controllably raise the temperature of the tissue without destroying the tissue to increase the level of heat shock protein activation in the tissue.
[Claim 91 The process of claim 8, wherein the treatment radiation has a

wavelength between 600nm-1100nm, an average power of between 1.0 and

6.94 watts, and forms treatment spots having a diameter between 100-500

microns.
[Claim 10] The process of any one of claim 8 or claim 9, wherein during an

interval of time, comprising less than one second, between pulses of treatment radiation applied to a first treatment area of the tissue, simultaneously applying the treatment radiation beams to a second treatment area of the tissue sufficiently spaced apart from the first treatment area of the tissue to avoid thermal tissue damage of the target tissue and repeatedly simultaneously applying, in an alternating manner during the same treatment session, the treatment radiation beams to each of the first and second treatment areas of the tissue until a predetermined number of applications to each of the first and second treatment areas of the tissue has been achieved.
[Claim 11] The process of any one of claims 8 to 10, wherein the average

power of the treatment radiation is selected to be monotonically lower within its

range when the treatment radiation spot size is selected to be smaller within its

range and/or when the total pulsed treatment radiation duration is selected to

be higher within its range.
[Claim 12] The process of any one of claims 8 to 11, wherein the treatment

radiation spot size, total pulsed treatment radiation train duration and average

power are selected based on thermal properties of the retinal tissue being

treated.
[Claim 13] The process of any one of claims 8 to 12, wherein the light

beams have a duty cycle of between 2.5% and 5%.
[Claim 14] A process for heat treating retinal tissue, comprising the steps

of:

generating a plurality of spaced apart pulsed treatment radiation beams

having a wavelength between 600nm and 1100nm and an average power

selected from a range of between 1.0 to 6.94 watts and a duty cycle between

2.5% and 5%;

applying the treatment radiation beams to retinal tissue such that a

plurality of treatment spots each having a diameter selected from a range of

between 100-500 microns are formed in a treatment area of the retinal tissue

for a duration selected from a range of between 30-800 milliseconds such that

the retinal tissue is heated to between six and eleven degrees Celsius during

the application of the treatment radiation beams to the retinal tissue while

providing thermal relaxation periods between pulses such that the average

temperature rise of the tissue over six minutes or less is maintained at

approximately one degree Celsius or less, whereby a therapeutic effect is

created without permanently damaging or destroying the tissue;

applying the treatment radiation beams to the tissue for a first period of

time comprising the selected total pulsed train duration of 30-800 milliseconds

to stimulate heat shock protein activation in the tissue;

halting the application of the treatment radiation beams for an interval of

time that exceeds the first period of time comprising 10 to 90 seconds; and

re-applying the treatment radiation beams to the tissue after the interval

of time within a single treatment session so as to controllably raise the temperature of the tissue without destroying the tissue to increase the level of heat shock protein activation in the tissue; wherein the average power of the treatment radiation is selected to be monotonically lower within its range when the treatment radiation spot size is selected to be smaller within its range and/or when the total pulsed treatment radiation duration is selected to be higher within its range.
[Claim 15] The process of claim 14, wherein the treatment radiation beams

are applied to at least a portion of the fovea of the eye.
[Claim 16] The process of claim 14 or claim 15, wherein during an interval

of time, comprising less than one second, between pulses of the treatment

radiation beams applied to the first treatment area of the tissue, including the

steps of:

simultaneously applying the treatment radiation beams to a second

treatment area of the tissue sufficiently spaced apart from the first treatment

area of the tissue to avoid thermal tissue damage of the target tissue and

repeatedly simultaneously applying, in an alternating manner during the same

treatment session, the treatment radiation beams to each of the first and

second treatment areas of the tissue until a predetermined number of

applications to each of the first and second treatment areas of the tissue has

been achieved.
[Claim 17] The process of any one of claims 14 to 16, wherein the

treatment radiation spot size, total pulsed treatment radiation train duration

and average power are selected based on thermal properties of the retinal

tissue being treated.
[Claim 18] A system for heat treating biological tissue, comprising:

a treatment radiation generator for generating a pulsed treatment

radiation having a duty cycle of between 2.5% to 10%, a wavelength between

570 nm and 1300 nm and an average power of between 0.0000069 to 37.5

watts;

the system including,

applying a first treatment to biological tissue by applying treatment

radiation to the biological tissue over a first period of time comprising a total

pulse train duration of between 30ms-800ms such that at least one treatment

spot having a diameter between 10-700 microns is formed on the biological

tissue and the biological tissue is heat stimulated sufficiently by the first

treatment to stimulate a first level of heat shock protein activation without

permanently damaging or destroying the tissue,

halting the application of the treatment radiation to the biological tissue

for an interval of time comprising between 3 seconds and 3 minutes, and

applying a second treatment to the biological tissue that received the

first treatment after the interval of time by applying treatment radiation to the biological tissue over a second period of time comprising a total pulse train duration of between 30ms-800ms such that the second treatment heats the biological tissue and stimulates a second level of heat shock protein activation in the biological tissue that is greater than the first level of heat shock protein activation without permanently damaging or destroying the tissue.
[Claim 19] The system of claim 18, the system includes heating the

biological tissue to between six and eleven degrees Celsius during the

application of the treatment radiation to the tissue, wherein the average

temperature rise of the tissue over several minutes is maintained at

approximately one degree Celsius or less.
[Claim 20] The system of either of claims 18 or 19, wherein the treatment

radiation is applied to the tissue during each of the first and second periods of

time for a duration of between 100-600 milliseconds.
[Claim 21] The system of any of claims 18 to 20, wherein the treatment

radiation is applied to retinal tissue of an eye, and preferably to at least a

portion of the fovea of the eye.
[Claim 22] The system of any of claims 18 to 21, wherein the treatment

radiation generator generates treatment radiation having a wavelength between

600 nm-1100 nm, an average power of between 0.00015 and 6.94 watts, and

forms at least one treatment spot having a diameter between 100-500 microns.
[Claim 23] The system of any of claims 18 to 22, wherein a plurality of

spaced apart beams of treatment radiation are generated and simultaneously

applied to the tissue to form a plurality of spaced apart treatment spots in a

first treatment area.
[Claim 24] The system of any of claims 18 to 23, wherein during an interval

of time, comprising less than one second, between pulses of treatment

radiation applied to the first treatment area of the tissue, the treatment

radiation beams are applied to a second treatment area of the tissue sufficiently

spaced apart from the first treatment area of the tissue to avoid thermal tissue

damage of the target tissue and are repeatedly applied, in an alternating

manner during the same treatment session, to each of the first and second

treatment areas of the tissue until a predetermined number of applications to

each of the first and second treatment areas of the tissue has been achieved.