Intraocular lens performance in air, in water, and in situ: a computer study

Computer analysis is used to predict performance of four intraocular lenses with assigned values of aberration. Cylinder error and asphericity error are used as examples of possible manufacturing errors. Three measures of performance are calculated: maximum optical path difference, root mean square optical path difference, and modulation transfer function. For evaluation in air these standard test conditions are assumed: collimated green light incident on the convex surface of a plano-convex lens, with a 3 mm aperture. All four lenses show substantially improved performance in water compared to air, and a further improvement in the simulated eye (i.e., in situ). However, an aberrated 30 diopter (D) lens with performance in air comparable to an aberrated 20 D lens, performs worse in situ than does the 20 D lens. This suggests that a performance test in air that is suitable for a 20 D lens (e.g., 100 line pairs per millimeter resolution) may not be adequate for a 30 D lens. A test in air at 30% resolution efficiency may be more suitable.