Survey of the optical quality of intraocular lens implants

Abstract

Intraocular lenses (IOLs) from 15 U.S. firms were tested for conformance to the requirements of the American National Standards Institute Z80.7 standard for IOLs. A total of 162 IOLs were tested for resolution, astigmatism, and accuracy of labeled power. Average resolving power was 78% of the diffraction limit, much better than the ANSI minimum requirement which is typically equivalent to 30% of the diffraction limit. This suggests that the ANSI Z80.7 requirement could be significantly tightened with little effect on current production practices. Only one IOL exhibited astigmatism in excess of 0.25 diopter. Differences between measured and labeled power in excess of 0.50 diopter were found in 22 lenses, indicating that accuracy of refractive power may be the most commonly missed optical requirement of the standard.

Optomechanical eye model with imaging capabilities for objective evaluation of intraocular lenses

“…At the same time, few reports give a comparative optical characterization of some IOLs, [1][2][3][4][5] and in a few cases they are limited to an analysis of the optical quality of the lenses. [6][7][8][9] On the other hand, many clinical studies have evaluated and compared the visual outcomes in large patient populations after lens extraction and IOL implantation. This approach clearly represents an indirect evaluation of the optical properties of an IOL because they are merged in a number of surgical, biological, and individual masking factors, thus requiring hundreds of subjects to reach statistical relevance.…”

IOL power mislabelling

“…There seems to be few reports on true mislabelling of lens implants (Olson et al 1979;Olson 1980;Grossman et al 1991). Prompted by four cases in our clinic with unexpected high refractive errors after cataract surgery, we decided to develop a method of measuring lens implant power in order to be able to check the accuracy of the power label.…”