Optical design of intraocular lenses. II. Off-axis performance.

The effect of intraocular lens shape on off-axis performance of model pseudophakic eyes was investigated. Image quality criteria included an optimization procedure, spot diagrams, and the modulation transfer function (MTF). The optimum lens shape varies with lens fitting position, corneal asphericity, and pupil size. An earlier investigation showed that the optimum lens shape for on-axis imagery is approximately plano-convex, with the more curved surface facing the cornea. In this investigation, optimum lens shapes for a 10 degrees off-axis position ranged from near this shape to near the reversed shape, i.e., the more curved surface facing the retina. Because the on-axis case should carry more weight and because conditions favoring the reverse form include small pupils for which image quality is fairly insensitive to variations in lens shape, it is suggested that good forms for intraocular lenses range from plano-convex (curved surface facing cornea) to equi-convex.