Contact lens having an index of refraction approximating that of human tears

Abstract

A wettable contact lens of the type applied to the human eye to correct vision deficiencies, said lens formed of a transparent, dimensionally stable, solid material characterized by an index of refraction approximating that of the human tears.

We claim: 
     
       1. A contact lens for providing optical correction to a human eye, said lens having a generally concavo-convex cross section with the concave surface adjacent to the eye and comprising a transparent, dimensionally stable, nontoxic polymer characterized by an index of refraction no greater than 1.40 and closely matching the index of refraction of human tears, and selected from the group consisting of polymers of hexafluoroacetone-tetrafluoroethylene-ethylene, polymers of perfluoroalkylethyl methacrylates, and polymers of perfluoro-2-methylene-4-methyl-1.3-dioxolane. 
     
     
       2. The contact lens of claim 1 in which the posterior surface of said lens conforms with the topography of a human eye, and said polymer is characterized by an index of refraction of no greater than 1.37. 
     
     
       3. The contact lens of claim 2 in the form of a scleral lens. 
     
     
       4. The contact lens of claim 1 characterized by an index of refraction no greater than 1.35. 
     
     
       5. The contact lens of claim 1 in which said transparent dimensionally stable, nontoxic polymer comprises a polymer of hexafluoroacetone-tetrafluoroethylene-ethylene. 
     
     
       6. The contact lens of claim 1 in which said transparent, dimensionally stable, nontoxic polymer comprises a polymer of a perfluoroalkylethyl methacrylate. 
     
     
       7. The contact lens of claim 6 in which the transparent, dimensionally stable, nontoxic polymer comprises a polymerized perfluoroalkylethyl methacrylate in which the alkyl group contains from .Badd..[.3 to 14.]..Baddend. .Iadd.4 to 12 .Iaddend.carbon atoms. 
     
     
       8. The contact lens of claim 7 in which the transparent, dimensionally stable, nontoxic polymer comprises a polymerized perfluoroalkylethyl methacrylate in which the alkyl group contains .Badd..[.3.]..Baddend. .Iadd.8 .Iaddend.carbon atoms. 
     
     
       9. The contact lens of claim 1 in which said transparent, dimensionally stable, nontoxic polymer comprises a polymer of perfluoro-2-methylene-4-methyl-1.3-dioxolane. 
     
     
       10. The contact lens of claim 9 in which the transparent, dimensionally stable, nontoxic polymer comprises a copolymer of perfluoro (2-methylene-4-methyl-1.3-dioxolane) and tetrafluoroethylene. 
     
     
       11. The contact lens of claim 10 in which said copolymer is composed of from 50 to 95 percent by weight of perfluoro (2-methylene-4-methyl-1.3-dioxolane) and from 5 to 50 percent by weight of tetrafluoroethylene. .Iadd. 12. A solid, dimensionally stable corneal contact lens for providing optical correction to a human eye; said lens comprising a transparent, dimensionally stable non-toxic polymer and being characterized by reduced aberrations due to reflected light; said lens having both an anterior surface and a posterior surface shaped to provide optical correction; said lens having a refractive index no greater than 1.40 and having sufficient permeability to oxygen and carbon dioxide to permit circulation therethrough for nutrition of the cornea. .Iaddend..Iadd. 13. The contact lens defined in claim 12 wherein said lens has a Knoop hardness of at least 2. .Iaddend..Iadd. 14. The contact lens defined in claim 12 wherein said lens has a Knoop hardness of at least 4. .Iaddend..Iadd. 15. The contact lens defined in claim 12 wherein said lens includes minute holes to permit transport of oxygen to the cornea. .Iaddend. .Iadd. 16. The contact lens defined in claim 12 wherein said polymer has sufficient permeability to oxygen and carbon dioxide to permit circulation therethrough for nutrition of the cornea. .Iaddend..Iadd. 17. The contact lens defined in claim 12 wherein the periphery of the lens is rounded to provide a comfortable fit. .Iaddend. .Iadd. 18. The contact lens defined in claim 12, wherein said lens has a refractive index closely matching the index of refraction of human tears. .Iaddend.