Intraocular lenses with surface aspherization: interferometric study

Purpose. To accurately evaluate in an optical laboratory two different types of intraocular lenses (IOLs). @ Methods. In this study, optical testing facilities based on interferometry were used. The IOLs were inspected with laser light, and interference patterns were acquired and processed, obtaining the physical parameters accounting for the lens behavior. Comparison of the respective performances within the pseudophakic eye was provided in terms of modulation transfer function (MTF) using lens diameters from 3.0 mm to 5.0 mm. The data were inserted in a mathematical model of the eye, and the relevant merit functions were computed with a ray-tracing program. @ Results. Sample sets of both all-spherical IOLs and IOLs with aspherical surfaces were inspected. The interferometric maps showed clear evidence of the opposite wave aberration introduced by the different IOL types. With a 3.0 pupil diameter, both IOL types performed as almost ideal lenses, while with a 5.0 mm diameter, IOLs with aspherical surfaces effectively compensated for the spherical aberration of the cornea and had a significantly higher MTF. @ Conclusions. The interferometric approach to IOL testing provided accurate data on the physical parameters of the IOL. With a measuring and computing chain that includes eye modeling and ray tracing, it was possible to analyze in detail the process by which IOLs with aspherical surfaces compensate for the spherical aberration of the cornea under photopic, mesopic, and scotopic conditions,