Optics: eye examining – vision testing and correcting – Spectacles and eyeglasses – Ophthalmic lenses or blanks
Reexamination Certificate
2000-09-16
2002-11-12
Sugarman, Scott J. (Department: 2873)
Optics: eye examining, vision testing and correcting
Spectacles and eyeglasses
Ophthalmic lenses or blanks
C351S16000R
Reexamination Certificate
active
06478423
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to contact lenses. More particularly, it relates to contact lens substrate s made of one material and coated with another and methods for selecting and preparing such combinations to achieve good physiological performance of the coated lenses.
Coating a substrate of one material with a different material has been proposed as a strategy for making contact lenses for a variety of reasons. The coating may offer a property or properties that are different from those of the substrate and which are particularly desirable as a lens surface apart from the bulk properties of the lens material itself. Properties such as wettability, resistance to proteinaceous deposits, biocompatability, UV shielding and other desirable lens characteristics and properties could conceivably be addressed with this approach.
U.S. Pat. No. 5,779,943, for example, proposes preparing a molded article such as a contact lens by coating a bulk polymer with a latent hydrophilic material in the mold. The molded article is made more wettable at its surface. WO 96/24392 to Morra, et al., proposes coating a substrate with hyaluronic acid to improve biocompatability. One proposed use for the coated substrate is in intraocular lenses. WO 94/06485 proposes coating a hydrophobic substrate with a carbohydrate to make the device from which it is made more wettable at its surface. WO 93/00391 proposes coating a hydrogel with a hydrophilic coating polymer to make the substrate more hydrophilic and less prone to adhesion by tear proteins. U.S. Pat. No. 5,708,050 proposes coating a lens substrate with a silicone oil, a polysaccharide, or a denatured collagen to make it more hydrophilic at its surface. Beyond a general recognition that wettability and oxygen permeability are desirable lens characteristics, little insight has been provided on substrate/coating selection and application criteria for physiological compatibility. That is, there has been little guidance available for determining substrate and coating materials and application conditions that will provide good physiological performance.
Simply coating a lens substrate made from hydrophobic monomers with a hydrophilic coating material without accounting for such critical parameters will not alleviate the problems such as dryness and surface deposition described above. It has not been possible to predict the success of a given lens/coating combination or coating process until lenses made from the material were placed in actual physiological conditions. Thus, materials that have appeared to provide favorable properties have often manifested the negative conditions described above only when actually placed in contact with a wearer's eye. This has left the selection of suitable coated contact lens materials and coating methods largely an empirical art with little ability to predict even the physiological effect of lot to lot variations in contact lens manufacturing processes.
Polymers made from silicones and other hydrophobic materials (e.g., polyfluorinated polymers and polypropylene glycol) used as contact lens materials present particular challenges that might be addressed with coating processes. The oxygen permeability of such lens materials can be very high making them desirable in many instances. However, the surfaces of such materials typically do not provide desirable levels of wettability. This, among other properties of lenses made from hydrophobic materials can result in dryness, grittiness, and general discomfort. The surfaces of such polymers also tend to have an affinity for certain tear components such as proteins, lipids and mucin. This can result in increased surface deposition and fouling with opaque deposits when worn. Such lenses can also become tightly adhered to the cornea, potentially leading to serious damage to the corneal epithelium. Plasma coating processes, aqueous and organic coating processes, and surface derivitization have all been described as potential methods for coating the hydrophobic lens material or changing its wettability at the surface.
The field of contact lens production could benefit greatly from a predictive method for selection and production of materials without undue reliance on testing in physiological conditions. While one cannot eliminate such testing, better predictive models will streamline materials selection processes by reducing the number of different options to be tested. They would also provide a means for distinguishing useful and beneficial materials combinations and lenses from materials combinations and lenses that are not so useful or beneficial during manufacturing and testing of lenses.
BRIEF SUMMARY OF THE INVENTION
The invention is a process for coating a contact lens substrate with another material to achieve desirable physiological performance. In one aspect of the invention, the substrate is coated with coating that will have a surface area expansion factor greater than one. The coated lenses have low physical defect and low surface roughness. Preferably, they have a sub-micron coating thickness.
In another aspect of the invention, a lens substrate made from hydrophobic monomers is coated with a hydrophilic material having a surface area expansion factor greater than one.
In yet another aspect of the invention, a method of coating a contact lens comprises selecting a lens substrate material, selecting a coating material which will have a surface area expansion factor greater than one relative to the lens substrate material, coating the lens substrate material with the coating material, and forming and selecting coated lenses having low physical defect and surface roughness profiles.
DETAILED DESCRIPTION OF THE INVENTION
Good physiological performance is obtained in coated lenses made according to this invention. For the purposes of this specification, good physiological performance or physiological compatibility is marked by a lens which when in contact with the eye results in good clinical comfort (average comfort>40 on 50 point subjective scale), good wettability (non-invasive tear break up time (NIBUT)>5 sec), minimal corneal disruption (average maximum type corneal staining≦1), and minimal on-eye lens spoiling (average deposits≦slight). A lens that meets these criteria is a physiologically compatible contact lens as the term is used throughout this specification.
Virtually any substrate that can be fashioned into a contact lens can be used in this invention provided it is optically transparent and is oxygen permeable. Suitable substrates include polymers made from hydrophobic materials such as silicone copolymers, interpolymers, oligomers, and macromers. Illustrative polysilicones are polydimethyl siloxane, polydimethyl-co-vinylmethylsiloxane. Other silicones are the silicone rubbers described in U.S. Pat. No. 3,228,741 of Becker issued Jan. 11, 1966; blends such as those described in U.S. Pat. No. 3,341,490 of Burdick et al., issued Sep. 12, 1967 and silicone compositions such as described in U.S. Pat. No. 3,518,324 of Polmanteer, issued Jun. 30, 1970. Substrates described in U.S. Pat. Nos. 4,136,250; 5,387,623; 5,760,100; 5,789,461; 5,776,999; 5,849,811; 5,314,960 and 5244,981 are also particularly suitable for use in this invention. Cross-linked polymers of propoxylate of methyl glucose and propylene oxide and HEMA-based hydrogels are different classes of substrates amenable to the process of this invention.
Preferred silicone compositions useful in forming the substrate of this invention are the cross-linked polysiloxanes obtained by cross-linking siloxane prepolymers by means of hydrosilylation, co-condensation and by free radical mechanisms such those described by Chen in U.S. Pat. No. 4,143,949 which is incorporated herein by reference. More preferred silicone-based substrates are cross-linked polymers of &agr;,&ohgr;-bisamionpropyl polydimethylsiloxane, and gylycidyl methacrylate, cross-linked polymers. The particularly preferred substrates are silicone compositions that are made from combining a methacrylate one or more
Copper Lenora L.
Heaton John C.
Jen James S.
Steffen Robert B.
Turner David C.
Johnson & Johnson Vison Care, Inc.
Sugarman Scott J.
Volyn Todd
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