Obtaining a high-quality retinal image with a biconvex intraocular lens.

We investigated the quality of the retinal image provided by a conventional, plano-convex intraocular lens by calculating the point spread function using a wide-angle model of the eye. We then calculated the ratio of the front and back curvatures for a biconvex lens with the conventionally used refractive index (1.491) using Seidel's aberration formulas. The point spread function for this intraocular lens was better than that of the conventional plano-convex lens. THe calculated ratio, which depends on the refractive index and the depth of the anterior chamber, was 3.16 (refractive index, 1.491; anterior chamber, 3.5 mm). As the depth of the anterior chamber decreases, the best ratio increases whereas the total power of the intraocular lens decreases. If an asymmetric intraocular lens is used, the greater curvature must face the cornea.