Silicone intraocular lenses and negative dysphotopsia

Abstract

An article by Henderson et al.1 compared the incidence of negative dysphotopsia associated with a silicone intraocular lens (IOL) (LI61AO, Bausch & Lomb, Inc.) with that of an acrylic IOL (Acrysof SN60WF, Alcon Laboratories, Inc.). Oddly, and in distinction to previous reports, they found no negative dysphotopsia with the silicone IOL.2,3 They attributed this, in part, to the round edge of the silicone IOL, and, among other parameters, they impugn the square edge of the acrylic IOL. However, the authors are in error with respect to the edge of the silicone IOL because the LI61AO has a continuous square-edged design.A Therefore, the contention that negative dysphotopsia did not occur with the LI61AO because of the round edge design is incorrect. Previously, we reported negative dysphotopsia in cases with the Crystalens (Bausch & Lomb, Inc.), a silicone IOL with a square edge; more noteworthy, we reported negative dysphotopsia with the AQ2010V (Staar Surgical Co.) and the SI-40NB (Abbott Medical Optics, Inc.), both silicone IOLs with round edges.2 Similarly, Trattler et al.3 reported negative dysphotopsia with round-edged silicone IOLs. We agree that negative dysphotopsia occurs more frequently with acrylic IOLs with a high index of refraction; however, negative dysphotopsia indeed does occur with silicone IOLs with round as well as square edges. Concerning the square edge as a contributing factor to negative dysphotopsia, the authors failed to acknowledge the information from Burke and Benjamin,4 who reported 5 patients with chronic negative dysphotopsia with various in-the-bag IOLs; all cases were “cured” by removing the in-the-bag IOL and replacing it with an Acrysof IOL (MA60AC, Alcon Laboratories, Inc.) implanted in the ciliary sulcus, above the capsular bag. The high index of refraction and square-edged design of the Acrysof IOL did not induce, but rather improved, negative dysphotopsia when the IOL was moved anterior to the capsular bag, in agreement with us2 and Vámosi et al.,5 that negative dysphotopsia occurs only with an in-the-bag IOL. In essence, negative dysphotopsia can occur when the capsule overlies the optic, but not when the optic overlies the capsule. We have reported that elevating the optic portion (of an existing IOL) anterior to the lens capsule (reverse optic capture) alleviates negative dysphotopsia; similarly, using this method as a primary strategy prevents negative dysphotopsia in the second eyes of symptomatic cases.2 Henderson et al.1 indicated that all their cases with negative dysphotopsia had the IOL in-the-bag with a fully overlapped anterior capsule remnant. We strongly believe the evidence is clear that negative dysphotopsia is associated with in-the-bag IOLs only and that it might occur with virtually any IOL. Given this, we cannot help but conclude that the anterior capsule–anterior lens surface interface must play a role in causing negative dysphotopsia. Nonetheless, we fully agree with the authors that the incidence of symptomatic negative dysphotopsia varies with the IOL material, index of refraction, and edge design. Surface reflectivity is another parameter that has yet to be investigated.