STANDARDIZED METHODS FOR ASSESSING THE IMAGING QUALITY OF INTRAOCULARLENSES

The relative merits of three standardized methods for assessing the im aging quality of intraocular lenses are discussed based on theoretical modulation-transfer-function calculations. The standards are ANSI Z80 .7 1984 from the American National Standards Institute, now superseded by ANSI Z80.7 1994, and the proposed ISO 11979-2 from the Internation al Organization for Standardization. They entail different test config urations and approval limits, respectively: 60% resolution efficiency in air, 70% resolution efficiency in aqueous humor, and 0.43 modulatio n at 100 line pairs/mm in a model eye. The ISO working group found tha t the latter corresponds to 60% resolution efficiency in air in a ring test among eight laboratories on a sample of 39 poly(methyl) methacry late lenses and four silicone lenses spanning the power (in aqueous hu mor) range of 10-30 D. In both ANSI Z80.7 1994 and ISO 11979-2, a 60% resolution efficiency in air remains an optional approval limit. It is concluded that the ISO configuration is preferred, because it puts th e intraocular lens into the context of the optics of the eye. Note tha t the ISO standard is tentative and is currently being voted on. (C) 1 995 Optical Society of America