Speed of capsular bend formation at the optic edge of acrylic, silicone, and poly(methyl methacrylate) lenses

Abstract

Purpose To evaluate how and how fast a capsular bend is created clinically at the optic edge of an intraocular lens (IOL) after cataract surgery. Setting Jinshikai Medical Foundation, Nishi Eye Hospital, Osaka, Japan. Methods Capsular bend formation was observed by slitlamp after maximum pupil dilation in 45 eyes of 45 patients with senile cataract. Fifteen eyes each received an AcrySof® MA60BM acrylic (Alcon), PhacoFlex II® SI-40NB silicone (Allergan), or UV26T poly(methyl methacrylate) (PMMA) (Menicon) IOL. Patients were evaluated prospectively at 1 day and 1, 2, and 4 weeks and retrospectively (15 eyes per IOL) 1 year after cataract surgery. A capsular bend index was developed to document and categorize the capsular bend formation process at the IOL optic edge. Results The anterior and posterior capsules adhered, with the latter attracted to the former. The adhesion always progressed from the periphery to the optic edge so that the posterior capsule eventually wrapped around the posterior optic edge, although not fully circumferentially in all cases. The process took place in 4 stages. Capsular bend formation was complete 1 month after surgery with the foldable IOLs (AcrySof, PhacoFlex II) but was significantly delayed with the PMMA IOL. After 1 year, the capsular wrapping was firm and fully circumferential at the optic edge with all IOL types in all cases. Conclusions Capsular bend formation progressed in the same fashion but at significantly different speeds among the IOLs, suggesting that the process depends on IOL material and design. Fast, early capsular bend formation may be 1 reason AcrySof and PhacoFlex II IOLs prevent PCO statistically better than PMMA IOLs. The results indicate that PCO is prevented by the sharp capsular bend created by sharp optic edges and by quick bend formation.