Ford JG, Karp CL. Cataract Surgery and Intraocular Lenses: A 21st-Century Perspective. 2nd ed. Ophthalmology Monograph 7. San Francisco: American Academy of Ophthalmology; 2001.

Hoffer KJ. Personal history in bifocal intraocular lenses. In: Current Concepts of Multifocal Intraocular Lenses. Maxwell WA, Nordan LT, eds. Thorofare, NJ: Slack; 1991:chap 12, pp 127–132.

Accommodating Intraocular Lenses

These lenses are essentially monofocal IOLs designed to allow some degree of improved near vision. Usually, such designs involve linking accommodative effort to an anterior movement of the IOL, thereby increasing its effective power in the eye. This mechanism may be more effective with higherpower IOLs because their effective powers are more sensitive to small changes in position than are those of lower-power IOLs. The US Food and Drug Administration (FDA) has approved one design that has shown some degree of accommodation, and other designs are awaiting FDA approval. At this time, there is no clinical evidence that “accommodating” IOLs actually change axial position in the eye during near-vision tasks.

Findl O, Kiss B, Petternel V, et al. Intraocular lens movement caused by ciliary muscle contraction. J Cataract Refract Surg. 2003;29(4):669–676.

Langenbucher A, Huber S, Nguyen NX, Seitz B, Gusek-Schneider GC, Küchle M. Measurement of accommodation after implantation of an accommodating posterior chamber intraocular lens. J Cataract Refract Surg. 2003;29(4):677–685.

Matthews MW, Eggleston HC, Hilmas GE. Development of a repeatedly adjustable intraocular lens. J Cataract Refract Surg. 2003;29(11):2204–2210.

Matthews MW, Eggleston HC, Pekarek SD, Hilmas GE. Magnetically adjustable intraocular lens. J Cataract Refract Surg. 2003;29(11):2211–2216.

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 axialpower 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 US Food and Drug Administration 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 UV 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.

Chapter Exercises

Questions