Long-term Posterior Capsule Opacification Reduction with Square-Edge Polymethylmethacrylate Intraocular Lens: Randomized Controlled Study

Abstract

Purpose: To objectively assess the long-term posterior capsule opacification (PCO) and neodymium-doped yttrium aluminium garnet (Nd:YAG) capsulotomy rate of a square-edge (SE) polymethylmethacrylate (PMMA) intraocular lens (IOL) modification in comparison with a round-edge (RE) PMMA IOL or an SE hydrophobic acrylic IOL (SE-Acrylic).

Design: Prospective, randomized, controlled fellow eye clinical study.

Participants: Ninety-four patients scheduled for bilateral phacoemulsification had an SE-PMMA IOL implanted in 1 eye. An RE-PMMA IOL was implanted in the fellow eye in 46 patients (group A), and an SE-Acrylic IOL was implanted in the fellow eye in 48 patients (group B). Randomization was used to determine group assignment and which IOL was implanted in the first eye to undergo surgery.

Methods: Evaluation of Posterior Capsule Opacification (EPCO) image analysis software was used to objectively grade PCO density from standardized, high-resolution retroillumination photographs obtained annually for the first 5 postoperative years and at year 9.

Main outcome measures: The PCO scores and Nd:YAG capsulotomy rate.

Results: Nine-year follow-up was achieved by 72% from group A and 63% from group B. In group A, the mean PCO score was significantly lower in the SE-PMMA IOL eyes compared with the contralateral RE-PMMA eyes at all follow-up visits (P < 0.05). In group B, the mean PCO score was statistically lower in the SE-PMMA IOL eyes compared with the contralateral SE-Acrylic IOL eyes at all but the 1- and 3-year follow-up visits. Nine-year Nd:YAG capsulotomy rates were 2% for SE-PMMA IOLs versus 37% for RE-PMMA IOLs in group A (P < 0.001), and 4% for SE-PMMA IOLs versus 10% for SE-Acrylic IOLs in group B (P = 0.435). The RE-PMMA PCO rate did not plateau and continued to increase throughout the 9-year study period.

Conclusions: This prospective, 9-year fellow eye comparison study suggests that an inexpensive PMMA IOL design modification-a squared optic edge-could significantly reduce the burden of vision-impairing secondary membrane in developing countries.