Patent ID: 6082856
Filing Date: 2000-07-04
Classification: G02C

Abstract:
A method for constructing a soft contact lens having a prescribed power correction for focusing light on the retina of an eye, said method comprising:constructing an eye model including a cornea, a crystalline lens and a retina;selecting a shape for an anterior surface of the cornea to be a conic section having an eccentricity in the range of about 0.14<e<0.63;selecting a preliminary soft contact lens having a center thickness, a radius, a posterior contact lens surface and an anterior contact lens surface to provide a prescribed plus or minus correction power such that, when applied to the anterior surface of the cornea, the anterior contact lens surface defining a conic section having a shape factor in the range of 0<E<1 or -1<E<0;performing an analysis using the preliminary soft contact lens and eye model tracing light ray paths through the contact lens/eye system;varying the shape factor of the anterior contact lens surface when applied to the anterior surface of the cornea to achieve an contact lens/eye system wherein a trace of light ray paths is optimized for sharpest focus by minimizing a retinal spot size of the rays, the shape factor being varied within the range of 0<E<1 or -1<E<0, thereby defining an optimized anterior contact lens surface for the soft contact lens when applied to the anterior surface of the cornea;calculating a thickness profile for the optimum contact lens using the differences in distance between the anterior surface of the cornea and the optimized anterior contact lens surface at various values of the contact lens radius from the center of the contact lens; anddetermining a shape for manufacture of said soft contact lens by selecting a first surface for said soft contact lens and calculating a second surface for said soft contact lens using said first surface and said thickness profile.