Intraocular Lens Standards
The American National Standards Institute (ANSI) and the International Standards Organization (ISO) set standards for IOLs. Among these standards is one for IOL power labeling; it requires that IOLs with powers labeled as less than 25 D be within ±0.40 D of the labeled power and have no axial-power variations of more than 0.25 D. IOLs labeled 25–30 D must be within ±0.50 D of the labeled power, and those labeled greater than 30 D must be within ±1.0 D. Most ophthalmologists are unaware of this wide range allowed for the labeling of high-power IOLs. Although controversial, attempts are being made to narrow this allowed range so that all IOL powers would be within ±0.25 D of the labeled powers. Actual mislabeling of IOL power is rare but still occurs.
In addition to the labeling standards, the ANSI, ISO, and FDA have set various other IOL standards for optical performance, a term that refers broadly to the image quality produced by an IOL. Lenses are also tested for biocompatibility, the absence of cytotoxicity of their material, the presence of any additives (such as ultraviolet filters), genotoxicity, and photostability, as well as for their safety with YAG lasers. There are also standards for spectral transmission. Physical standards exist to ensure adherence to the labeled optic diameter, haptic angulation, strength, and mechanical fatigability of the components, as well as to ensure sterility and safety during injection.
Excerpted from BCSC 2020-2021 series : Section 3 - Clinical Optics. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.