IOL types form capsular bends at different speeds

OSAKA, Japan – Capsular bends at the edge of an IOL optic form at significantly different speeds among different types of IOLs, according to a study here. The phenomenon occurs in the same fashion in all IOLs but at different rates, suggesting that the process depends on IOL material and design, the study authors found.

Capsular bends are formed when the anterior and posterior lens capsules wrap themselves around the edges of an IOL optic after IOL implantation. Okihiro Nishi, MD, and colleagues found that fast, early capsular bend formation may be one reason foldable IOLs prevent posterior capsular opacification better than PMMA IOLs. Their results indicate that PCO is prevented by the sharp capsular bend created by sharp optic edges and by quick bend formation.

Capsular bend formation was observed by slit lamp 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 PMMA (Menicon) IOL. Dr. Nishi developed a capsular bend index to document and categorize the capsular bend formation process at the IOL optic edge.

The adhesion always progressed from the capsule periphery to the optic edge, so that the posterior capsule eventually wrapped around the posterior optic edge, although not fully circumferentially in all cases. 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.

This study is published in the March issue of the Journal of Cataract and Refractive Surgery.