JP4792266B2 - Ophthalmic measuring device calibrator - Google Patents

Description

  The present invention relates to a calibrator for an ophthalmologic measurement apparatus, and more particularly, irradiates a laser beam to an eye to be examined, collects and scans the inside of the anterior chamber, analyzes the scattered light from the anterior chamber, and performs flare measurement, cell The present invention relates to a calibrator for an ophthalmologic measurement apparatus that is used as a measurement object for calibration of an ophthalmologic measurement apparatus that performs predetermined ophthalmic measurement such as measurement and is used at a position that should be occupied by an eye to be examined with respect to the apparatus.

  Conventionally, the anterior chamber is irradiated with laser light, focused in the anterior chamber, scanned, scattered light from cells or proteins in the anterior chamber, and the received light signal is analyzed. There are known ophthalmologic measuring apparatuses that measure the cell number density (cell measurement) or the protein concentration (flare measurement).

  Calibration is performed in the final inspection in the manufacture of such an ophthalmic measurement apparatus. In the measurement for the calibration, a sample in which cells in the anterior chamber are modeled is measured. As the sample, a blood cell diluted with a buffer solution or a latex particle diluted is used. These samples are usually measured in a four-sided transparent glass cell. The cornea of the eyeball is a curved surface, whereas the surface of the glass cell is a flat surface. Therefore, when measuring the sample put in the glass cell, an optical system for correcting the positional deviation of the condensing point of the light projecting system and the positional deviation of the condensing point of the light receiving system is required. A calibrator as a measurement object for calibration of an ophthalmic measurement apparatus is configured from these optical systems and the above-described sample, and is placed at a position that should be occupied by the eye to be measured with respect to the ophthalmic measurement apparatus and used for measurement for calibration. It was.

  In addition, a configuration is known in which an ophthalmic measurement apparatus is calibrated by regarding light transmitted through a slit having a width approximately the same as that of cells in the anterior chamber as scattered light from the cells (Patent Document 1). ).

Further, in the calibration inspection by the user, there is a method in which a calibrator attached to the ophthalmic apparatus main body performs measurement by dimming the light source light with a diffusion plate, confirms the apparatus state, and calibrates the measured value.
JP-A-7-51229

  Conventional calibrators using latex particles have the disadvantage that they are unstable due to large changes in characteristics over time due to biological and chemical changes in the calibrator itself, and the number of particles in the measurement area is Since it constantly changes depending on the adjustment technique and measurement environment, the measurement value is unstable, and there is a problem that cells cannot be completely modeled with latex particles.

  Further, in the calibration as in Patent Document 1, since the aging of the characteristics due to biological changes and chemical changes of the calibrator itself is small, calibration with good reproducibility can be performed, but in terms of cell modeling, it is not perfect. There is a problem that accurate calibration cannot be performed.

  In the calibration inspection by the user, only the light source light attenuated by the diffusion plate is measured, the reflected light from the specific calibration target substance is not measured, and it is obtained when the actual eyeball is measured. There is a disadvantage that a signal different from the signal pattern to be measured is measured, and that reliable calibration cannot be performed, and that cell measurement cannot be calibrated.

  Therefore, the present invention has been made to solve such problems, and can perform calibration with high reproducibility at the time of flare measurement and cell measurement, and can perform accurate flare measurement and / or cell measurement. It is an object to provide a calibrator for an ophthalmic measurement apparatus.

The present invention
In order to calibrate an ophthalmologic measuring apparatus that scans the anterior chamber of the eye to be examined with laser light, receives scattered light from the anterior chamber by the laser light by a light receiving means, analyzes the received light signal, and performs a predetermined ophthalmic measurement And a calibrator for an ophthalmologic measurement device that is used in a position to be occupied by an eye to be examined with respect to the device,
A neutral density filter arranged so that it can be inserted into and removed from the optical path to adjust the intensity of the laser beam;
A reflector disposed in the vicinity of the position of the condensing point of the laser light,
The reflection plate is arranged so that the front surface reflection light or the back surface reflection light from the reflection plate by the laser light is not received by the light receiving means, and from the reflection plate when the reflection light plate is irradiated with the laser light. Calibration is performed by measuring scattered light.

  In the present invention, each component of the calibrator is stable and has no biological change or chemical change. Therefore, the calibration is more stable and accurate than the calibration using a solution such as latex particles. It becomes.

  In addition, since the light reflected on the front surface or back surface is not received by the light receiving means from the reflector plate, the same scattered light as protein and latex particles can be measured with high reliability and reproduced. Highly calibrated.

  Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

  FIG. 1 shows an example of an ophthalmologic measurement apparatus by irradiating an eye to be examined with laser light, condensing and scanning in the anterior chamber, and receiving and analyzing scattered light from cells or proteins in the anterior chamber. 1 shows an apparatus for measuring cell density or protein concentration in the anterior chamber.

  In the figure, laser light emitted from a laser light source 41 is enlarged and paralleled by lenses 42 and 43, scanned two-dimensionally by galvanometer mirrors 44 and 45, and in front of the eyeball 54 of the eye to be examined by a condenser lens 46. It is collected in the chamber.

  When laser light is irradiated to cells or proteins existing in the anterior chamber, the laser light is scattered. The scattered light is condensed by the imaging lens 47 in a direction of approximately 90 ° with respect to the laser light irradiation direction, the optical path is divided by the half mirror 48, and one is imaged by the lens 53. To do. The other passes through the lens 49, forms an image on the light receiving mask 50 for limiting the field of view, and the scattered light that has passed through the light receiving mask 50 is converted into an electric signal by the photomultiplier 51, and then the arithmetic unit 52. And the number of cells in the measurement volume in the anterior chamber is measured, or the protein concentration is measured.

  At this time, the laser beam is scanned in the observation direction of the light receiving system. In an accurate sense, an image of the laser beam is not always formed on the light receiving mask 50, but in practical use. no problem. Normally, when a laser beam being scanned is irradiated onto a cell, the refractive index of a substance surrounding the cell differs from the refractive index of the cell, so that a spike-like signal as shown by an arrow in FIG. Observed. Therefore, if this spike-like signal is recognized using some analysis technique, the number of cells in the measurement volume determined by the scanning range of the laser light and the field of view of the light receiving mask can be counted. Counting the number of cells in such a measurement volume is called cell measurement.

  Further, for example, the scattered light signal at time points t10 and t20 in FIG. 2 indicates the protein concentration (flare value) in the anterior chamber, so that only one of the galvanometer mirrors 44 and 45 is driven and the other is fixed, By scanning light one-dimensionally, the difference between the scattered light intensity and the background value within a predetermined section (for example, between time points t10 and t20) is measured as a flare value. Measuring such a flare value (turbidity) is called flare measurement.

  The present invention provides a calibrator for calibration at the time of flare measurement or cell measurement in the final inspection of the manufacturing of the ophthalmic measurement apparatus. In the case of calibration at the time of flare measurement, the calibration is shown in FIG. Such a calibrator 10 is used.

  The calibrator 10 is disposed at a position to be occupied by the eye 54 in FIG. 1, and the laser beam incident from the condenser lens 46 is incident to calibrate the flare measurement of the ophthalmologic measurement apparatus. The calibrator 10 includes a reflection plate 1 made of the same material in a solid shape such as an acrylic plate (for example, acrylite manufactured by Mitsubishi Rayon Co., Ltd.), and an ND filter 2 for dimming incident laser light. .

  The scattering property inside the reflecting plate 1 has the same scattering characteristics as the protein in the anterior chamber. The reflecting plate 1 has a laser beam condensing point 41a (a measuring point in the anterior chamber of the eye to be examined). Is arranged at the center of the reflecting surface of the reflecting plate 1 so as to be approximately at the center in the thickness direction. Note that the laser beam diameter does not change so much as to affect the measurement even at a position away from the laser light condensing point, so that the condensing point 41a is strictly located at the center in the thickness direction of the reflector. There is no need.

  Further, the reflector 1 is arranged so that all the measurement points of the ophthalmologic measurement apparatus are present therein. At this time, as shown in FIG. 5, the laser beam is scanned from the bottom to the top in the drawing as a one-dimensional scanning line 6 at the time of calibration at the time of flare measurement.

  Further, as shown in FIG. 4, the reflecting plate 1 is inclined by a predetermined angle θ (about 60 degrees in the illustrated example) with respect to the incident optical axis A of the laser beam, and the surface by the laser beam from the surface 1a of the reflecting plate. The reflected light 3 and the back surface reflected light 4 from the back surface 1 b are not incident on the imaging lens 47 and are not received by the light receiving mask 50 and the photomultiplier tube 51.

  The laser scanning line 6 shown in FIG. 5 is shown as a virtual line in FIG. Further, in FIG. 4, in order to avoid complication, the refraction of the light path due to the difference in the refractive index between the reflector and the other is ignored.

  In such a configuration, the calibrator 1 is arranged as shown in FIGS. 3 and 4 at the time of calibration during flare measurement of the ophthalmic measurement apparatus. Further, only one of the galvanometer mirrors 44 and 45 is driven, one of them is fixed, and the laser beam is scanned one-dimensionally. When the laser beam is one-dimensionally scanned, the laser beam passes through the reflector 1 at times t1 to t4 as shown in FIG. A measurement window 7 indicated by an imaginary line is set in the measurement unit, and the laser beam enters the measurement window 7 at time t2 and leaves the measurement window 7 at time t3.

  The measurement window 7 has a substantially conjugate relationship with the light receiving mask 50.

  The scattered light 5 from the inside of the reflecting plate 1 (condensing point 41 a) by this one-dimensional scanning is condensed by the imaging lens 47 and detected by the photomultiplier tube 51 through the light receiving mask 50. At this time, a scattered light signal is obtained from the photomultiplier tube 51 as shown in FIG. The time t1 to t2 corresponds to the Y1 section of the laser scanning range Y. In this section, scanning is performed outside the measurement window 7, so that the background value BG1 is obtained. Times t2 to t3 correspond to the section Y2 of the laser scanning range Y, and in this section, scanning is performed within the measurement window 7, so that a signal value S is obtained. Times t3 to t4 correspond to the Y3 section of the laser scanning range Y. In this section, scanning outside the measurement window 7 is performed, so that the background value BG2 is obtained. A value obtained by subtracting the average value of the background values BG1 and BG2 from the signal value S in the section Y2 of the measurement window 7 becomes the flare value F by the calibrator. Then, this flare value F is compared with an initial flare value F ′ (for example, a flare value obtained when using the calibrator 10 at the time of factory shipment), and F ′ / F is obtained as a correction coefficient. After calibrating in this way, the calibrator is removed, and the flare value of the eye to be inspected is measured as shown in FIG. The actual flare value is obtained by multiplying the measured value by the correction coefficient obtained during the calibration.

  In the conventional calibration method, it was necessary to measure the background value and the signal value separately, but according to the present invention, both values are measured in one operation (measurement) and the correction coefficient is calculated. Is possible.

  Further, the surface reflected light 3 by the laser light from the surface 1 a of the reflector 1 and the back reflected light 4 from the back surface 1 b do not enter the imaging lens 47, but enter the light receiving mask 50 and the photomultiplier tube 51. Since no light is received, a signal value with a good S / N ratio can be obtained, and a reliable calibration is possible.

  The reflecting plate used for the calibrator in the turbidity measurement may be other than an acrylic plate as long as the surface is reflective and translucent solid (an optical material that does not interfere with straightness). For example, a substance that is transparent to some extent and causes internal scattering can be considered. For example, a flare waveform can be obtained even with a reflective plate made of a transparent adhesive or a colored glass plate, and a reflective plate for calibration during flare measurement can be obtained.

  Further, since the ND filter 2 of the calibrator can be inserted into and removed from the optical path, a plurality of types of neutral density filters having different dimming levels are provided, one of the filters is inserted into the optical path, and the laser light incident on the reflector 1 It is also possible to calibrate at different intensities by changing the intensity of.

  When performing cell measurement with the ophthalmologic measurement apparatus of FIG. 1, when calibrating the apparatus, as shown in FIG. 6, as a reflector of the calibrator 10 of FIG. The plate-shaped vapor deposition glass 21 given to the back surface 21b of transparent glass is used. The vapor deposition film 22 is illustrated by halftone dots in FIG. 6, and the white circle portion 22a is not a vapor deposition portion, but the entire back surface 21b, thereby obtaining a vapor deposition pattern composed of a plurality of white circles. The white circle portions 22a serve as a cell model in the anterior chamber, have the same scattering characteristics as the scattered light of latex particles, and are arranged at equal intervals on a concentric circle. A line connecting the white circles on each concentric circle is a straight line passing through the center of the concentric circle. In addition, the circumference of a broken line in FIG. 6 is an imaginary line for showing a concentric circle.

  At the time of calibration, both the galvanometer mirrors 44 and 45 are driven at different frequencies, and the vapor deposition glass 21 is two-dimensionally scanned with the laser beam 26 as shown in FIG. Scattered light from the vapor deposition glass 21 is detected by the photomultiplier tube 51 through the imaging lens 47.

  FIG. 7 shows a beam path of laser light when one scanning line 26a passes through one white circle portion 22a. Since the reflecting plate of the vapor deposition glass 21 is disposed at a predetermined angle θ with respect to the optical axis A as in the case of the reflecting plate 1, the reflected lights 23 and 24 from the front surface 21a and the rear surface 21b of the vapor deposition glass 21 are It does not enter the imaging lens 47 and is not received by the light receiving mask 50 and the photomultiplier tube 51. On the other hand, the pseudo-scattered light 25 enters the imaging lens 47 from the white circle portion 22a of the vapor deposition pattern and is received by the light receiving mask 50 and the photomultiplier tube 51. Since the scattered light signal received by the photomultiplier tube 51 shows a peak as shown by an arrow line in FIG. 9, when the deposition pattern is scanned two-dimensionally, a peak signal 30 based on each white circle portion 22 of the deposition pattern. Occur in time series. Since the peak signal 30 protrudes from the background signal 31 from the vapor deposition film 22, the number of white circles, that is, the number of model cells can be counted by counting the peak signal.

  The scattering intensity of the model cell obtained by the above calibration at the time of shipment from the factory is recorded as an initial value V ′, and if the scattering intensity of the model cell obtained at the time of actual calibration is V, V ′ / V is corrected. Calculated as a coefficient. Then, a measurement value obtained by multiplying the measurement value obtained by performing cell measurement using the apparatus of FIG. 1 by the correction coefficient is set as an actual cell measurement value.

  When the laser beam is scanned two-dimensionally, the laser beam condensing point does not necessarily coincide with the position of each white circle portion. The beam diameter does not change so much, the peak value of each peak signal 30 changes to some extent, and there is no problem in counting the peak signal. There is no need to hit.

  Further, in order to obtain better scattered light from each white circle portion of the non-deposition portion, a substance having a scattering property may be deposited on each white circle portion.

  Moreover, although the vapor deposition pattern is applied to the back surface 21b of the transparent glass, it may be applied to the front surface 21a.

  Similarly to the time of flare measurement, calibration with different laser intensities is possible by inserting / removing the ND filter 2 or using an ND filter having a different light attenuation.

  In any of Examples 1 and 2, each component of the calibrator is stable and has no biological or chemical change, so it is more stable and more reproducible than calibration using a solution such as latex particles. Calibration is possible.

  In addition, the substance concentration in the measurement area of each reflector is constant, and the signal pattern obtained from the reflector is similar to the signal pattern obtained from the measurement target (protein or latex particles). It is possible to calibrate the measured value by detecting a signal having the same pattern as the signal obtained at the time of measurement.

  In addition, since a flare signal and / or cell signal having a desired magnitude can be obtained by providing an ND filter and changing the light source light amount, the sensitivity of the light receiving element such as a photomultiplier tube and the scattered light intensity can be obtained. The linearity can be easily confirmed.

  In addition, since the scanning method changes according to the reflector 1 or 21 to be used, calibration during flare measurement and calibration during cell measurement can be performed smoothly.

It is the block diagram which showed the optical structure of the ophthalmic measurement apparatus calibrated with the calibrator of this invention. It is a wave form diagram which shows the waveform of the scattered light signal measured with an ophthalmologic measurement apparatus. It is the block diagram which showed the optical structure of the calibrator. It is explanatory drawing which shows the path | route of the various light rays from the reflecting plate of a calibrator. It is a wave form diagram which shows the relationship between a reflecting plate and a scanning line, and the waveform of the scattered light signal from the reflecting plate of a calibrator. It is a perspective view of the vapor deposition glass used for a calibrator. It is explanatory drawing which shows the path | route of the various light rays from vapor deposition glass. It is explanatory drawing which showed the state which carries out the two-dimensional scan of vapor deposition glass. It is a wave form diagram which shows the waveform of the scattered light signal from vapor deposition glass.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Reflector 2 ND filter 21 Evaporated glass 46 Condensing lens 47 Imaging lens

Claims (4)

In order to calibrate an ophthalmologic measuring apparatus that scans the anterior chamber of the eye to be examined with laser light, receives scattered light from the anterior chamber by the laser light by a light receiving means, analyzes the received light signal, and performs a predetermined ophthalmic measurement And a calibrator for an ophthalmologic measurement device that is used in a position to be occupied by an eye to be examined with respect to the device,
A neutral density filter arranged so that it can be inserted into and removed from the optical path to adjust the intensity of the laser beam;
A reflector disposed in the vicinity of the position of the condensing point of the laser light,
The reflection plate is arranged so that the front surface reflection light or the back surface reflection light from the reflection plate by the laser light is not received by the light receiving means, and from the reflection plate when the reflection light plate is irradiated with the laser light. A calibrator for an ophthalmologic measuring apparatus, wherein calibration is performed by measuring scattered light. The calibrator for an ophthalmologic measurement apparatus according to claim 1, wherein a plurality of types of the neutral density filter are provided. The reflector is composed of the same material in a solid form, and is arranged so that all measurement points of the measuring device exist inside the reflector, and calibrates by measuring the internal scattered light by the laser beam scanned one-dimensionally. ophthalmic measuring apparatus for calibration of claim 1 or 2, characterized by performing. The said reflecting plate is comprised with the vapor deposition glass which gave the vapor deposition pattern to at least one surface, and calibrates by measuring the scattered light from the pattern by the laser beam which carried out the two-dimensional scan on the vapor deposition pattern. The calibrator for ophthalmic measuring apparatus according to 1 or 2 .

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