DETERMINING THE IMAGING QUALITY OF INTRAOCULAR LENSES

Purpose: To validate the proposed optical requirements of a draft inte rnational standard for intraocular lenses (IOLs). Setting: Eight optic al testing laboratories in the United States, Germany, Japan, and The Netherlands. Methods: The testing laboratories performed modulation tr ansfer function (MTF) tests on various IOLs using a model eye and visu al resolution tests in air. Each laboratory performed duplicate measur ements on a set of 43 lenses that was circulated among the testing lab oratories. Results: The interlaboratory tests showed that the MTF meas urements using a model eye had better repeatability and reproducibilit y than the more common industry practice of resolution testing in air with parallel light and the United States Air Force three-bar target. However, the two methods correlated well. The commonly applied criteri on that an IOL resolve in air at least 60% of the Rayleigh cutoff spat ial frequency corresponded to a minimum requirement of 0.43 MTF units at 100 mm(-1) in a model eye. Conclusions: Either criterion may be app lied in accordance with a proposed international standard for IOLs. Th e model eye method can be applied over a broader range of dioptric pow ers and is relevant for materials that interact with aqueous. Both tes ts appear to have a greater ability to detect unwanted surface aberrat ions than resolution testing of IOLs in a water cell using parallel li ght, a described in the current American National Standards Institute standard.