GB2174397A - Hard contact lenses and methods of manufacture - Google Patents
Hard contact lenses and methods of manufacture Download PDFInfo
- Publication number
- GB2174397A GB2174397A GB08509924A GB8509924A GB2174397A GB 2174397 A GB2174397 A GB 2174397A GB 08509924 A GB08509924 A GB 08509924A GB 8509924 A GB8509924 A GB 8509924A GB 2174397 A GB2174397 A GB 2174397A
- Authority
- GB
- United Kingdom
- Prior art keywords
- lens
- hard contact
- hydrophilic
- plasma
- lenses
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 238000000034 method Methods 0.000 title claims abstract description 16
- 238000004519 manufacturing process Methods 0.000 title claims description 8
- 239000000463 material Substances 0.000 claims abstract description 17
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical group [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 12
- 239000001301 oxygen Substances 0.000 claims abstract description 12
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 12
- 239000000080 wetting agent Substances 0.000 claims abstract description 11
- 229920001577 copolymer Polymers 0.000 claims abstract description 9
- 239000007789 gas Substances 0.000 claims abstract description 7
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims abstract description 6
- 239000011261 inert gas Substances 0.000 claims abstract description 5
- 230000005672 electromagnetic field Effects 0.000 claims abstract description 4
- 229910052786 argon Inorganic materials 0.000 claims abstract description 3
- 239000013590 bulk material Substances 0.000 description 4
- 229920003229 poly(methyl methacrylate) Polymers 0.000 description 4
- 239000004926 polymethyl methacrylate Substances 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- RZVAJINKPMORJF-UHFFFAOYSA-N Acetaminophen Chemical compound CC(=O)NC1=CC=C(O)C=C1 RZVAJINKPMORJF-UHFFFAOYSA-N 0.000 description 3
- 229920006217 cellulose acetate butyrate Polymers 0.000 description 3
- 239000005297 pyrex Substances 0.000 description 3
- 230000002209 hydrophobic effect Effects 0.000 description 2
- CERQOIWHTDAKMF-UHFFFAOYSA-N Methacrylic acid Chemical compound CC(=C)C(O)=O CERQOIWHTDAKMF-UHFFFAOYSA-N 0.000 description 1
- VVQNEPGJFQJSBK-UHFFFAOYSA-N Methyl methacrylate Chemical compound COC(=O)C(C)=C VVQNEPGJFQJSBK-UHFFFAOYSA-N 0.000 description 1
- 210000004087 cornea Anatomy 0.000 description 1
- 238000004132 cross linking Methods 0.000 description 1
- KPUWHANPEXNPJT-UHFFFAOYSA-N disiloxane Chemical class [SiH3]O[SiH3] KPUWHANPEXNPJT-UHFFFAOYSA-N 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 230000007794 irritation Effects 0.000 description 1
- 150000002605 large molecules Chemical class 0.000 description 1
- 150000002632 lipids Chemical class 0.000 description 1
- 229920002521 macromolecule Polymers 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 125000005375 organosiloxane group Chemical group 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 230000008961 swelling Effects 0.000 description 1
- 238000011282 treatment Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02C—SPECTACLES; SUNGLASSES OR GOGGLES INSOFAR AS THEY HAVE THE SAME FEATURES AS SPECTACLES; CONTACT LENSES
- G02C7/00—Optical parts
- G02C7/02—Lenses; Lens systems ; Methods of designing lenses
- G02C7/04—Contact lenses for the eyes
Landscapes
- Health & Medical Sciences (AREA)
- Ophthalmology & Optometry (AREA)
- Physics & Mathematics (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Eyeglasses (AREA)
- Treatments Of Macromolecular Shaped Articles (AREA)
Abstract
Hard contact lenses are made by cutting individual lenses from bulk siloxane acrylate copolymer material which has been previously treated so as to incorporate a wetting agent. The individual lenses are then placed in a partially evacuated chamber enclosed by a reactor through which gas is passed in the pressure of an electromagnetic field in order to generate in the reactor a plasma glow discharge which renders the surface of the lenses more hydrophilic. In one method the gas passed through the reactor is oxygen, and in another an inert gas such as argon is passed through the reactor, followed by oxygen.
Description
SPECIFICATION
Improvements in hard contact lenses
Field of the Invention
This invention relates to hard contact lenses and also to a method of making such lenses.
Background to the Invention
Hard contact lenses made from polymethyl methacrylate (PMMA) have been known in the art for several years. Oxygen transport through PMMA contact lenses is extremely low which means that the lenses cannot be worn continuously for extended periods. Since the cornea normally receives its oxygen directly from the atmosphere, the PMMA lens wearer often experiences corneal swelling and irritation due to prolonged oxygen deprivation.
Recently, cellulose acetate butyrate (CAB) has been used in an attempt to provide a hard contact lens which will transport oxygen. Although CAB has modest permeability, it lacks a number of the mechanical characteristics which are essential for successful contact lens fabrication.
More recently, siloxane containing copolymers have been introduced as oxygen permeable hard contact lens materials. These polymeric compositions are generally prepared by copolymerising methyl methacrylate with siloxanyl alkyl ester of the methacrylic acid. Due to the essentially hydrophobic nature of materials containing organosiloxane groups, wetting agents are incorporated to render the surface wettable, to promote comfort for the wearer. However, it has been found that as more wetting agent is incorporated so the mechanical properties of the lens material deteriorate. There is thus a 'trade off' between surface wettability and mechanical properties, and because of this, wettability may still be insufficient for certain circumstances and for some wearers. An alternative to the incorporation of wetting agents has been to surface treat the lens using plasma glow discharge methods.Such methods render the surface of the lens material more hydrophilic but such treatments lack permanence because any scratches or modifications expose the hydrophobic bulk material of the lens.
An object of the invention is to provide a hard contact lens, and a method of making such a lens, wherein both the lens surface and the bulk material of the lens are hydrophilic to an extent not found in the prior art.
Summary of the Invention
According to one aspect of the invention there is provided a hard contact lens made from a siloxane acrylate copolymer material which has been treated with a wetting agent to render the bulk of the material hydrophilic and wherein the surface of the lens has been rendered more hydrophilic by exposure of the lens to a plasma glow discharge. Hence, in the inventive lens not only is the bulk of the material hydrophilic, but the surface is rendered more hydrophilic as a result of the plasma glow discharge process. If the surface of the inventive lens is scratched the exposed bulk material is sufficiently hydrophilic to enable the lens to continue in use.
According to another aspect of the invention there is provided a method of making a hard contact lens from a siloxane acrylate copolymer material treated with a wetting agent so as to render the bulk of the material hydrophilic, wherein the surface of the lens is exposed to a plasma glow discharge to render the lens surface more hydrophilic. The plasma glow discharge is preferably formed by a non equilibrium plasma which may be a plasma generated in the presence of oxyen, or alternatively in the presence of an inert gas followed by oxygen.
In the preferred method to be described, individual contact lenses are cut from bulk siloxane acrylate copolymer material which has been treated so as to incorporate a wetting agent, the individual lenses then being placed in a partially evacuated chamber through which a gas is passed in the presence of an electromagnetic field which generates the plasma gas discharge.
A method of making a hard contact lens in accordance with the invention will now be described, by way of example, with reference to the accompanying drawing which shows diagrammatically apparatus for subjecting the lens to a plasma glow discharge.
Siloxane acrylate copolymer is first treated with a wetting agent so as to render the bulk of the material hydrophilic. Individual lenses are then cut from this bulk material and treated to the plasma glow discharge process in the apparatus shown in the drawing.
Referring to the drawing, a pyrex reactor 1 encloses a chamber partially evacuated through a pipe 13 leading to a pump (not shown) through the intermediary of a cold trap 4. Within the pyrex reactor 1 is a heated platform 7 on which the individual hard contact lenses 5 are placed. Pressure within the chamber is monitored by a Pirani pressure gauge 3.
The temperature of the platform 7 is controlled by an oil bath 6. An electromagnetic field is set up by means of a coil 14 powered from a radio frequency generator 9 through the intermediary of an inductance/capacitance matching network 10 and a power meter 11.
Gas is led into an inlet end 2 of the reactor 1, and the apparatus has two needle waves 8 in separate branches to enable two different gases to be led independently into the reactor
1.
There are two preferred methods: in the first, oxygen only is fed into the pyrex reactor
1, and in the second (which uses a two-stage process) an inert gas (such as argon) is sup plied to the reactor 1, followed by oxygen.
The second alternative may be preferred as the first stage has the effect of tightening the cross linking of the bonds in the surface layer of the contact lenses and the second stage reduces the contact angle, which is the angle which a water surface makes with the lens surface.
The pressure in the reactor 1 is typically 0.0 torr to 1 torr, the temperature is ambient temperature and the process may have a duration between 5 seconds and 2 minutes with a power level between 3 and 10 watts.
The resulting lenses have an exceptional level of biocompatibility and are substantially lipid and large molecule impermeable. The lenses have a contact angle which shows a two or three fold reduction in comparison with known hard contact lenses.
Claims (9)
1. A hard contact lens made from a siloxane acrylate copolymer material which has been treated with a wetting agent to render the bulk of the material hydrophilic, wherein the surface of the lens has been rendered more hydrophilic by exposure of the lens to a plasma glow discharge.
2. A method of making a hard contact lens from a siloxane acrylate copolymer material treated with a wetting agent so as to render the bulk of the material hydrophilic, wherein the surface of the lens is exposed to a plasma glow discharge to render the lens surface more hydrophilic.
3. A method according to claim 2, wherein the plasma glow discharge is formed by a non equilibrium plasma.
4. A method according to claim 2 or 3, wherein the plasma is generated in the presence of oxygen.
5. A method according to claim 2 or 3, wherein the plasma is generated in the presence first of an inert gas and then in the presence of oxygen.
6. A method according to claim 5, wherein the inert gas is argon.
7. A method according to any of claims 2 to 6, wherein individual contact lenses are cut from bulk siloxane acrylate copolymer material which has been treated so as to incorporate a wetting agent, the individual lenses then being
placed in a partially evacuated chamber through which gas is passed in the presence
of an electromagnetic field in order to gener
ate the plasma glow discharge.
8. A method of making a hard contact
lens, substantially as herein particularly de
scribed with reference to the accompanying
drawings.
9. A hard contact lens made by a method
according to any of claims 2 to 8.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08509924A GB2174397A (en) | 1985-04-18 | 1985-04-18 | Hard contact lenses and methods of manufacture |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08509924A GB2174397A (en) | 1985-04-18 | 1985-04-18 | Hard contact lenses and methods of manufacture |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8509924D0 GB8509924D0 (en) | 1985-05-30 |
| GB2174397A true GB2174397A (en) | 1986-11-05 |
Family
ID=10577837
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08509924A Withdrawn GB2174397A (en) | 1985-04-18 | 1985-04-18 | Hard contact lenses and methods of manufacture |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2174397A (en) |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1362939A (en) * | 1971-12-31 | 1974-08-07 | Agfa Gevaert Ag | Method for rendering silicone rubber surfaces hydrophilic |
| GB1487965A (en) * | 1973-10-25 | 1977-10-05 | Agfa Gevaert Ag | Method for increasing the hydrophilicity of a silicone rubber surface |
| GB2051844A (en) * | 1979-06-18 | 1981-01-21 | Shinetsu Chemical Co | Method for modifying surface properties of a shaped silicone article |
-
1985
- 1985-04-18 GB GB08509924A patent/GB2174397A/en not_active Withdrawn
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1362939A (en) * | 1971-12-31 | 1974-08-07 | Agfa Gevaert Ag | Method for rendering silicone rubber surfaces hydrophilic |
| GB1487965A (en) * | 1973-10-25 | 1977-10-05 | Agfa Gevaert Ag | Method for increasing the hydrophilicity of a silicone rubber surface |
| GB2051844A (en) * | 1979-06-18 | 1981-01-21 | Shinetsu Chemical Co | Method for modifying surface properties of a shaped silicone article |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8509924D0 (en) | 1985-05-30 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |