| 摘要 |
A method for constructing a soft contact lens having a prescribed power correction for focusing light on the retina of an eye is described. The method provides a soft contact lens that, when in place ("flexed") on the wearer's eye, is designed and manufactured to provide a substantially ellipsoidal anterior surface. In the method, an eye model including a cornea, a crystalline lens and a retina is constructed. Then a shape for an anterior surface of the cornea is selected to be a conic section having an eccentricity in the range of about 0.14<e<0.63. Next, a preliminary soft contact lens is selected 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. An analysis is performed using the preliminary soft contact lens and eye model tracing light ray paths through the contact lens/eye system. The shape factor of the anterior contact lens surface when applied to the anterior surface of the cornea is varied within the range of 0<E<1 or -1<E<0 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. Thus, an optimized anterior contact lens surface for the soft contact lens when applied to the anterior surface of the cornea is defined. A thickness profile is calculated 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. Contact lenses having the calculated thickness profile can be made by conventional methods. Both monofocal and multifocal lenses having optimized aberration correction can be made. |
