UV-absorbing intraocular lenses: safety, efficacy, and consequences for the cataract patient.

The crystalline lens absorbs most of the incident UV radiation between 300 and 400 nm and thereby protects the retina from a significant, potential source of photochemical damage. This protection is lost when the lens is removed by cataract surgery, but can be restored by the implantation of an intraocular lens (IOL) that has UV-absorbing chromophores incorporated into a polymethylmethacrylate (PMMA) substrate. Spectrophotometric data show that the various, commercially available, UV-absorbing IOLs are not equally effective in absorbing UV radiation; thus, a standard, quantitative metric for comparing their performance is proposed. Cytotoxicity and biocompatibility studies have failed to demonstrate that UV-absorbing IOLs are unsafe, even when damaged by Nd:YAG lasers used for photodiscission posterior capsulotomy. There are positive consequences for the pseudophakic patient with a UV-absorbing IOL, in that it may restore normal spectral sensitivity, reduce erythropsia and cystoid macular edema, and stabilize the blood-vitreous barrier.