AU642963B2 - Ophthalmic lenses based on amorphous fluoropolymers - Google Patents

Description

Our Ref: 352292 642963

AUSTRALIA

Patents Act COMPLETE SPECIFICATION FORM

(ORIGINAL)

Application Number: Lodged: a complete Specification Lodged: Accepted: Published: Priority: Related Art: 1 Applicant(s): Address for Service: Ciba-Geigy AG Klybeckstrasse 141 4002 BASLE

SWITZERLAND

ARTHUR S. CAVE CO.

Patent Trade Mark Attorneys Level 10, 10 Barrack Street SYDNEY NSW 2000 Complete specification for the invention entitled "Ophthalmic lenses based on amorphous fluoropolymers".

The following statement is a full description of this invention, including the best method of performing it known to me:-

I

la V-17969/1+2/=/TIT 12 Ophthalmic lenses based on amorphous fluoropolymers The invention relates to ophthalmic lenses, such as contact lenses and intraocular lenses, which essentially consist of amorphous fluoropolymers, to processes for the production of such lenses, to such processes, including subsequent surface treatments, and to the use of corresponding amorphous fluoropolymers for the production of contact lenses and intraocular lenses.

Amorphous fluoropolymers are further developments of polytetrafluoroethylene which has already been known for some decades. Amorphous fluoropolymers are disclosed, for example, in EP-A-073 087 or EP-A-111 343. According to EP-A-073 087, these are copolymers which are obtained from tetrafluoroethylene and perfluoro-2,2-dimethyl-1,3-dioxole, and possibly a third monomer, for example propylene, isobutylene or ethylene. Polytetrafluoroethylene compositions which are prepared, for example, using certain amounts of the abovementioned dioxole or derivatives thereof are disclosed in EP-A-111 343.

0 Since 1989, such amorphous fluoropolymers have also been commercially available.

S* Thus, Dupont markets the products Teflon AF 1600 and 2400, in which "AF" means "Amorphous Fluoropolymer". These products are copolymers of tetrafluoroethylene and perfluoro-2,2-dimethyl-1,3-dioxole.

According to EP-A-073 087, the amorphous copolymers disclosed therein are suitable for uses such as windows for chemical reactions, specifically in processes in which hydrogen fluoride is used or forms. The amorphous copolymers disclosed in EP-A-111 343 are described as being useful in making molded parts, specifically in instances where smooth surfaces are important, such as ball valve seats. The polymers Teflon AF 1600 and 2400 marketed by Dupont are described in the product description accompanying them as being suitable for coatings or coverings for optical devices, including those which are used within wide temperature ranges and in a chemically aggressive environment. Elsewhere in the advertising material it states that Teflon AF is an ideal candidate for optical devices for medicine, military, aerospace and industry.

It has now been found that, surprisingly, ophthalmic lenses having exceptionally advantageous properties can be produced from amorphous fluoropolymers. Contact lenses or intraocular lenses according to the invention thus have a combination of high hardness and oxygen permeability. They moreover have such a high glass transition point that they can be autoclaved. In addition, their crystallinity and refractive index are decidedly low. The refractive index can be, for example, made close to the refractive index of the lacrimal film, so that an optimum course of ray results. The refractive index can be adjusted, for example, by varying the nature and amount of comonomers used. According to the invention, for example, tonic contact lenses of low refractive index can thus also be produced. If intraocular lenses according to the invention are used, fewer complications in respect of secondary cataract formation are expected in view of the material properties.

If materials having a refractive index of between 1.47 and 1.52 are used and a contact lens geometry which is toric on the inside is used, an artificial residual astigmatism arises between the lacrimal fluid and lens material because of the differences in refractive index, and this then has to be corrected on the front curve of the lens with the aid of a toric surface. The production and fitting of such lenses is very expensive.

On the other hand, if a lens material according to the invention having a refractive index of between 1.31 and 1.33 is used to deal with relatively highly astigmatic corneas, there is either no jump or only a very small jump in refractive index. Correction of the undesirable artificial residual astigmatism is thus unnecessary. This makes the lenses and their fitting considerably cheaper.

If materials of relatively low refractive index are used, there is usually a non-optimal distribution of the overall thickness. In extreme cases, the relatively steep lenticular rise leads to incompatibility. However, this effect can be avoided by using a corneoscleral design. A corneoscleral design having diameters of between 11.5 and 13.5 mm not only leads to a general improvement in compatibility because of the large diameter, but allows a balanced division of the lens between the corneoscleral haptic and the optically active surface. The corneoscleral haptic can be designed perfectly here in respect of compability without taking into consideration the optical requirements. The unfavourable distribution of overall thickness which occurs at the low refractive index has an effect only in the optically active part and in no way affects the compatibility.

Another great advantage of the material according to the invention lies in the high oxygen permeability, which means that it is particularly predestined for corneoscleral design. Incorporating measures for adequate rinsing behind the contact lens "urbo effect, microlacrimation and the like), it is possible to use the material in combination with the corneoscleral design under particularly adverse circumstances, and moreover the material is suitable for wearing for several days.

The ophthalmic lenses according to the invention therefore combine a range of favourable parameters such as have not been described for contact lenses or intraocular lenses to da..

The invention therefore relates to ophthalmic lenses consisting essentially of an amorphous copolymer which comprises units of the formula I f* -CF- CF- I I 0 0 (CF,)a OF2

(I)

R R 2 and units of the formula II

-CF

2

-CF

2 (II) in which a and b independently of one another are zero, one or two, and in which R 1 and

R

2 independently of one another are perfluorinated lower alkyl.

o S Perfluorinated lower alkyl contains up to 7 carbon atoms, in particular up to 4 carbon atoms, and is, for example, perfluorinated methyl, ethyl, propyl, iso-propyl, butyl, isobutyl or tert-butyl, preferably trifluoromethyl.

The units of the formula I and of the formula II can be present as blocks or can alternate randomly. The content of units of the formula I is preferably at least 10 mol per cent and is particularly 10 to 80 mol The sum of the indices a and b in a unit of the formula I is preferably not greater than two.

The indices a and b are particularly preferably zero. In a specific embodiment, a and b are -4each zero and R 1 and R 2 in each case are perfluorinated C--C 4 alkyl, in particular trifluoromethyl. According to this embodiment, further comonomers can be dispensed with and the molar ratio of units of the formula I to units of the formula II is in the range from 30:70 to 90:10, preferably in a range from 50:50 to 85:15. Particularly preferred ratios of units of the formula I to those of the formula II are about 50:50 and about 80:20 ("about" in this connection is to be understood as meaning a deviation of not more than ±10 In addition to the units of the formula I and II, the copolymer can comprise other units in amounts of up to 40 mol of the copolymer. These units can also be in the form of blocks or can alternate randomly with one another or with units of the formula I and II. Suitable units here are those of the formula

III

-CF-CF

2

OR

3 in which R 3 is a perfluorinated alkyl radical of the formula CnF 2 n+ 1 in which n is 1 to 4, or in which R 3 is a perfluorinated cycloalkyl radical of the formula CmF 2 m 1 in which m is to 8, and/or those of the formula IV

-CX-CX'-

I I

(IV)

R

4

RS

5 in which X and X' independently of one another are hydrogen or fluorine and R 4 and R independently of one another are hydrogen, fluorine, lower alkyl or perfluorinated lower alkyl, eyr'ding those units of the formula IV in which X, R 4 and R 5 are fluorine.

A perfluorinated alkyl radical of the formula CnF 2 n+ 1 is, for example, perfluoromethyl, -ethyl or -propyl. A pzrfluorinated cycloalkyl radical of the formula CmF 2 m.

1 is, for example, perfluorocyclohexyl or -cyclopentyl. Perfluorinated lower alkyl R 4 or R 5 is as defined above for R 1

/R

2 Lower alkyl R 4 or R 5 has up to 7, preferably up to 4, carbon atoms and is, in particular, methyl, ethyl, propyl or butyl, The units of the formula IV comprise perfluorinated, partly fluorinated and fluorine-free units. Perfluorinated and fluorine-free units of the formula IV are preferred. The former are those, for example, in which X, X' and R 5 are fluorine and R 4 is perfluorinated lower alkyl. The latter are, for example, those in which X, X and R 5 are hydrogen and R 4 is lower alkyl. Partly fluorinated units of the formula IV are, for example, those in which X, X' and R 5 are hydrogen and R 4 is perfluorinated lower alkyl.

Units of the formula I and II together with units of the formula Ill or together with units of the formula IV, for example, can occur in the copolymer of which the ophthalmic lenses according to the invention consist. Combinations of units of the formula I and H with units of the formulae III and IV are also possible.

The total amount of units of the formula III and IV, where these are present, is preferably UP to 30 mol of the copolymer, and particularly preferably up to 20 mol of the copo- .*lymer. An embodiment of the invention which is likewise preferred comprises, however, 6* ophthalmic lenses of copolymers which consist to the extent of at least 90 mol more 0:609: appropriately to the extent of at least 95 mol and particularly preferably exclusively, of :units of the formula I and 11. Ophthalmic lenses, specifically contact lenses, of the commnercially available materials Teflon AF 1600 and Teflon AF 2400 or mixtures thereof are most preferred. According to the knowledge of the iniventors, these materials are copolymers such as are used according to claim 4, containing 50 mol and 80-90 mol respectively of units of the formula I.

The monomers which are required for the preparation of the copolymers are known or can 'e':be prepared in a manner which is known per se. For example, monomers which provide ***units of the formula I in the copolymer are described in US Patent 3 978 030. The mono- 6:mers, which provide units of the formula 11 or IV in the copolymer are all commercially obtainable. 'he monomers which provide units of the forula MIIin the copolymer are described in standard works, cf., for example, Houben-Weyl, supplement 1E20.

:The preparation of amorphous copolymers which are used for the preparation of the contact lenses according to the invention is described, for example, in EP-A-073 087 and EP-A-lll1343.

In view of the fact that the copolymers used according to the invention can be processed as thermoplastics, there is an abundance of possibilities of producing contact lenses from them. The amorphous copolymers in the form of, for example, granules, powders or films can in each case be used here as starting materials.

I f -6- The lenses according to the invention can thus be produced by processes which are known per se, such as static mould casting, spin casting, pressing, deep-drawing, thermoforming, lathe cutting or laser machining.

These process steps are known per se and therefore do not require more detailed expianation for the expert. However, liquid monomers or monomer mixtures or solutions of solid monomers which polymerise only in the course of the production of the lens or blank, are usually used as starting materials for the production of contact lenses. The peculiarity of the preparation processes according to the invention is that finished copolymers which are thermoplastic are used as the starting materials. These materials therefore also allow routes to be followed which are not usually taken for the production of contact lenses, alongside the classical contact lens production processes, such as lathe cutting of a button, spin casting or static mould casting in individual moulds, which, in some cases in modified form, can also be used with the present invention.

S Static mould casting can be carried out, for example, by injection moulding. For this, the amorphous copolymer is melted at temperatures of 160-240 0 C, preferably 210-220 0 C, and is injected into the mould by means of an injection moulding machine. If moulds with a base curve and front curve are used, contact lenses can be produced directly. It is furthermore possible to produce contact lenses by castig, by introducing a solution of the amorphous copolymer in an organic solvent into a mould with a concave curve and convex S curve, after which the solvent is allowed to evaporate. Suitable solvents in this and the fol- S lowing processes are, for example, perfluorinated ethers or perfluorinated hydrocarbons.

Spin casting can also be used according to the invention, by introducing a solution of the S amorphous copolymer into a mould for spin casting, after which the mould is rotated.

During this operation, the solvent evaporates. The finished contact lens, the dimensions of which can be controlled by the dimensions of the mould, the speed of rotation and the viscosity of the solution introduced, remains in the mould.

Pressing is carried out according to the invention, for example, by melting the amorphous copolymer and pressing it in a mould or by compression moulding a film of the amorphous copolymer. A film of the amorphous copolymer can be produced in a manner which is known per se, for example by extrusion, by blowing or by casting a solution of the amorphous copolymer.

A contact lens can also be produced in a manner which is known per se by deep-drawing or thermoforming from a film produced, for example, as mentioned above.

Lathe cutting is also suitable as the last process step for the production of contact lenses according to the invention. This always applies if, for example, a blank obtainable by one of the abovementioned processes requires further working. Lathe cutting is to be understood as meaning conventional machining of e.g. contact lens buttons. Corresponding blanks can be produced, for example, by injection moulding, extrusion of round rods and division thereof, casting from a solution or casting of a melt. The term contact lens blank in this connection includes buttons or semi-mould products, for example base curve blanks. Typical blanks have thicknesses of 4 or 6 mm and diameters of 10 to 17, for example 12 or 14 mm.

Laser machining can also be used according to the invention, blanks or contact lenses produced by one of the other processes being used as the starting material where they still S require additional fineworking of their surface.

Intraocular lenses according to the invention can also be produced in a manner which is known per se, for example by lathe cutting processes or by pressing from powder, S granules or film. Different haptics can be employed for intraocular lenses according to the invention. The haptic here can be intregrated into the mould shape, or subsequently shaped or cut out by laser cutting. Various haptics are described, for example, by P. Fechner in Intraokularlinsen, Grundlagen und Operationslehre (Intraocular Lenses, Principles and S* Operating Techniques), Ferdinand Enke Verlag, Stuttgart 1980.

As already mentioned, the ophthalmic lenses according to the invention have excellent o physical parameters, such as a high hardness and oxygen permeability. For example, hardnesses of 60-70 N/mm 2 and Dk values of 280-350 units have been measured. Corre< spondingly high hardnesses are otherwise only obtained at the expense of the Dk values, and vice versa. Thus, for example, conventional materials having a hardness of 60-70 N/mm' have Dk values of less than 100, and materials having Dk values of 150 have a hardness of 40 or less. The abovementioned combination of such a high hardness with such a high oxygen petmeability is therefore an outstanding property of the contact lenses and intraocular lenses according to the invention, which distinguishes them considerably and unexpectedly from theprior art. On the other hand, the wetting angle is comparatively high, so that it is desirable for the surface of the ophthalmic lenses according to the invention to be made more wettable, especially in the case of contact lenses.

This invention thus furthermore relates to a process for hydrophilising the ophthalmic lenses obtainable by the abovementioned processes and to lenses treated in this way. The hydrophilising can be carried out in a manner which is known per se. Suitable processes are, for example, treatment in plasma with gases, graft polymerisation with hydrophilic monomers, introduction of hydroxyl groups by modification of the units of the formula I or oxidation of copolymer constituents.

The treatment of, for example, contact lenses with gases in plasma is already known per se. Examples of gases which can be used are 02, 03, N 2 He, Ar, NH 3 or lower alkanes having, for example, up to 7 carbon atoms, such as CH 4 by themselves, as a mixture or as a mixture with water vapour. However, the treatment in plasma with gases in connection with this invention is not limited to the use of substances which are gases under normal conditions (temperature and pressure). Instead, the term "gases" in this connection also S includes, according to the invention, compounds which have such a high vapour pressure that they can produce a low pressure plasma. Examples of such compounds are low molecular weight alkanes, alkenes, alcohols, amines, aldehydes, carboxylic acids, carboxylic acid derivatives, such as hydrophilic esters or amides, and ethers, each of which can be used by themselves, as a mixture with one another or, for example, as a mixture with oxygen, air and/or water vapour. Low molecular weight in this connection means, in particular, compounds having a molecular weight of up to 200, preferably up to 140, particularly preferably up to 88.

Graft polymerisation with hydrophilic monomers is also already known, for example in accordance with EP-A-220 919. It can be carried out in plasma or in solution. Suitable hydrophilic monomers are the hydrophilic vinyl monomers usually used for contact lenses, S for example methacrylic acid, hydroxyethyl methacrylate, vinylpyrrolidone, N-vinylmethylacetamide, dimethylacrylamide or homologues thereof. This hydrophilisation measure is preferably carried out in suitable solvents, such as hydrocarbons, for example aromatic hydrocarbons, such as toluene or dimethylbenzene, or aliphatic hydrocarbons, for example hexane, and in the presence of agents which form free radicals, for example percompounds, for excmple hydrogen peroxide or peracids.

The units of the formula I always present in the contact lenses or intraocular lenses which have not undergone specific surface treatment can be converted, for example by acid I I I I -9hydrolysis or in a basic medium in the presence of a hydrogen transfer agent, into groups of the formula V

-CF-CF-

S I

(V)

OH OH the presence of which likewise increases the hydrophilicity of the surface, Examples of suitable reagents for this are alkali metals, such as sodium or potassium, preferably in solvents which can transfer hydrogen, such as ethers, in particular cyclic ethers, for example tetrahydrofuran, or in ammonia, or acids, such as inorganic or organic acids, for 1 example hydrochloric acid, sulfuric acid or trifluoroacetic acid. The ophthalmic lenses according to the invention can also be treated oxidatively in solution using oxidising agents, for example hydrogen peroxide or nitric acid.

The invention is illustrated below with the aid of examples, but these are not intended to limit the invention in any way. Temperatures are stated in degrees Celsius, A: Production of blanks, semi-finished lenses, contact lenses and intraocular lenses Example 1: Teflon AF 1600 or 2400 granules are melted in an injection moulding machine at 210-22000 in a suitable manner and injected into the mould. The injection mould is designed as a single- or multi-cavity mould. The follow-up pressure on the moulding composition and the cooling of the injection moulding in the mould are adjusted so that a substantially stress-free blank having a diameter of about 14 mm and a thickness of 6 mm is obtained. Residual stresses can be eliminated by subsequent annealing of the blanks under normal atmosphere or N 2 or in vaci)o at 110 0 C-140 0

C.

Alternatively, the polymer melted in an extruder is processed to round rods having a diameter of about 14 mm. The rods are annealed as a whole or cut into buttons 6 mm thick and annealed.

Example 2a: Granules are injected into an injection mould as described in Example 1. The mould is provided with inserts which are convex in shape. The radii of the inserts correspond to the base curves of the desired contact lenses (so-called base curve blanks). The radii are spherical. However, the base curve blanks can also be aspherical in shape, in particular elliptical. Alternatively, the inserts are provided with an incorporated lens diameter and lens edge. The final contact lens is obtained from these blanks by lathe cutting the front curve.

2b: According to this embodiment, the inserts are concave in shape, so that after the corresponding base curve has been machined by lathe cutting, a flat, collecting or scattering lens is obtained. Here also, the final lens diameter and the lens edge are alternatively incorporated.

Example 3: As in Example 1, granules are plasticised in a suitable manner and injected 0j. into a contact lens mould. The mould is shaped so that it reproduces the desired base curve, diopter, diameter, bevel and edge of the lens. The base curve is spherical, aspherical or, as a particular embodiment, elliptical, as required.

SExample 4: Granules or powder of Teflon AF 1600 or 2400 or a mixture thereof in a balanced amount are heated at 200 0 -220°C in a suitable pressing mould and compressed under pressure. The material or contact lens is allowed to cool in the mould, while maintaining the pressure. The mould used is shaped as a button mould, semi-mould (Example 2) or lens mould (Example The amount of granules or powder weighed out Sdepends on the mould used, as follows: for a button: 0.5-1.5 g for a semi-mould: 0.1-0.9 g for lenses: 15-100 mg.

So.. Example 5: Granules or powder of Teflon AF 1600 or 2400 are or is plasticised in a suitable plasticising unit and the material is pressed through a slit orifice. The resulting film i 0.2-0.5 mm thick is formed or pressed directly or later by a forming process, thermoforming, deep-drawing or compression moulding in a contact lens mould to give a contact lens or intraocular lens. Alternatively, corresponding films are produced by the blowing process.

Example 6: About 8-10 by weight of granules or powder of Teflon AF 1600 or 2400 are dissolved in a perfluorinated solvent, for example Galden® (Montedison) or Fluorinert® if necessary while heating. A film is produced from the solution by stripping off the solvent by heating, a fan or a vacuum. This film is shaped to a contact lens in accordance -11with one of the forming processes (see Example Example 7 A solution, obtained according to Example 6, of the copolymer is introduced into a prefabricated mould. The solvent is evaporated off by heating or in vacuo. The mould is constructed so that it reproduces the front face of the lens with its diopter, diameter and lens-edge configuration. The base curve is subsequently shaped using a corresponding punch with the radius incorporated.

Example 8: A solution obtained according to Example 6, is introduced into a prfabricated mould which turned about its own axis. The mould is constructed so that it reproduces the i front curve of the contact lens with its diopter. diameter and edge. The solvent is evaporated by heating, during which the mould iI simultaneously rotated. Various radii of the base curve are obtained by adjusting the speed of rotation (so-called spincast process).

B: Examples for hydrophilising contact lenses or intraocular lenses Example 9: Finished contact lenses according to one of the above examples are exposed to a corona discharge under normal atmosphere to improve the wettability. The contact lenses are then equilibrated with physiological saline solution. Thereafter, the surface can be wetted homogeneously.

9 S Example 10: Contact lenses according to the invention with an untreated surface are o exposed to a plasma discharge. This is generated in an atmosphere of 02 or 03. Water vapour can also be admixed to these gases. After a treatment time of 10 seconds to minutes, the lenses have a wetting angle of <400 (without treatment >100). The same results are achieved starting from N 2 He, Ar, NH 3 or CH 4 by themselves or as a mixture.

Example 11: Contact lenses according to the invention with an untreated surface are activated by means of Ar plasma. A hydrophilic surface is produced by graft polymers using hydrophile monomers such as methacrylic acid, HEMA, methacrylamide, vinylpyrroiido s O- N-vinylmethylacetamide. The same results are achieved starting from a plasma of N 2 or 02.

Example 12: The surfaces of contact lenses or intraocular lenses according to the invention having an untreated surface are activated with H 2 0 2 as a powerful agert which form free radicals, in a solution of hexane and subjected to graft polymerisation by adding -12hydrophilic monomers, as in Example 11. After equilibration with physiological saline solution, the wetting of the surface is significantly improved.

Example 13: Contact lenses according to the invention having an untreated surface are exposed to a solution of Na/NH 3 or Na/tetrahydrofuran (Tetra Etch®, Gore) in a dipping process. After treatment with acetone and then water, excess reagent is rinsed off and the lenses are equilibrated with physiological saline solution. The treatment is carried out for 1-60 seconds at room tempera'ture or at temperatures up to 100 0

C.

C

060

S

0

Claims (21)

1. An ophthalmic lens, which is selected from a contact lens and an intraocular lens, essentially consisting of an ariorphous copolymrer which comprises units of the formula I -CF--CF- 0 0 (CF2a CF2)b (I) C SR 1 R 2 and units of the formula II -CF 2 -CF 2 (H) Sin which a and b independently of one another are zero, one or two, and in which R and R 2 independently of one another are perfluorinated lower alkyl.

2. An ophthalmic lens according to claim 1, in which a and b are zero.

3. An ophthalmic lens according to claim 1, in which a and b are zero and R, and R 2 are perfluorinated C l -C 4 alkyl.

4. An ophthalmic lens according to claim 3, in which Ri and R 2 are trifluoromethyl. An ophthalmic lens according to claim 1, in which the molar ratio of units of the formula I to units of the formula I is in the range from 30:70 to 90:10.

6. An ophthalmic lens according to claim 1, which comprises units of the formula in -CF-CF 2 OR 3 in which R 3 is a perfluorinated alkyl radical of the formula CnF2n+ 1 in which n is 1 to 4, or I I -14- in which R 3 is a perfluorinated cycloalkyl radical of the formula CmF 2 m-1, in which m is to 8, and/or those of the formula IV -CX-CX'- I I (IV) R4 R in which X and X' independently of one another are hydrogen or fluorine and R 4 and R independently of one another are hydrogen, fluorine, lower alkyl or perfluorinated lower alkyl, excluding those units of the formula IV in which X, R 4 and R 5 are fluorine, in amounts of up to 40 mol of the copolymer.

7. An ophthalmic lens according to claim 6, in which the copolymer consists to the extent "I of at least 90 mol of units of the formulae I and II. 0 0

8. An ophthalmic lens according to claim 6, in which the copolymer comprises units of the formulae III in addition to units of the formula I and II.

9. An ophthalmic lens according to claim 6, in which the copolymer comprises units of the formulae III and IV in addition to units of the formula I and II.

10. An ophthalmic lens according to claim 8, in which a and b are zero.

11. An ophthalmic lens according to claim 9, in which a and b are zero.

12. An ophthalmic lens according to claim 1, which consists of Teflon AF 1600.

13. An ophthalmic lens according to claim 1, which consists of Teflon AP 2400. 9

14. An ophthalmic lens according to claim 1, which consists of a mixture of Teflon AF 1600 and Teflon AF 2400. An ophthalmic lens according to any one of claims 1 to 14, which is a contact lens.

16. An ophthalmic lens according to any one of claims 1 to 14, which is an intraocular lens.

17. A process for the production of an ophthalmic lens according to claim 1, which com- prises producing the lens, starting from an amorphous copolymer as defined in claim 1, by static mould casting, spin casting, pressing, deep-drawing, thermoforming, lathe cutting or laser machining,

18. The use of an amorphous copolymer as defined in claim 1 for the production of a contact lens.

19. The use of an amorphous copolymer as defined in claim 1 for the production of an intraocular lens. A process for hydrophilising the surface of an ophthalnmi lens according to claim 1, which comprises hydrophilising the surface in a manner which is known per se by treatment in plasma with gases, graft polymerisation with hydrophilic monomers, introduction of hydroxyl groups by modification of the units of the formula I or oxidation of the copolymer constituents. S

21. A process according to claim 20, wherein the surface is hydrophilised by plasma Streatment with gases.

22. A process according to claim 20, wherein the surface is hydrophilised by introduction of hydroxyl groups with an alkali metal in a solvent which transfers hydrogen.

23. A process according to claim 20, wherein the surface is hydrophilised by introduction of hydroxyl groups by means of acid hydrolysis.

24. A contact lens which is obtainable according to any one of the processes of claims 20-23. DATED this 27th day of August, 1993. CIBA--GEIGY AG By Its Patent Attorneys DAVIES COLLISO CAVE