The effects of the CAPR on PCO formation were examined 8 weeks after surgery by a single investigator (T.N.) in an unmasked fashion owing to the readily noticeable CAPR in the samples, which is a potential limitation of the study. We chose the examination timing of 8 weeks after surgery on the basis of a previous report by Legler et al6 in which a similar experimental design was used. Animals were killed by intravenous administration of a lethal dose of pentobarbital sodium. The eyeballs were enucleated before the corneas and posterior halves of the eyes were removed to isolate the anterior halves. These anterior segments were fixed in 10% neutral buffered formalin for 1 week and then embedded in a plastic (Technovit 7100; Heraeus Kulzer GmbH, Wehrheim, Germany). Six-micrometer sections were stained with toluidine blue before histologic observation by light microscopy. The degree of PCO was scored according to the following scales: adhesion of anterior capsule to posterior capsule, 0 (none), 1 (a little), 2 (less than half circle), 3 (more than half but not entire circle), or 4 (entire circle); regeneration of lens fiber in the capsular bag, 0 (none), 1 (a little), 2 (less than half circle), 3 (more than half but not entire circle), or 4 (entire circle); fibrosis of posterior capsule under the IOL optic, 0 (none), 1 (mild), 2 (moderate), or 3 (severe); and wrinkles in the posterior capsule, 0 (none), 1 (mild), 2 (moderate), or 3 (severe). The first 3 measures were determined by stereoscopic microscopy before sample fixation. Posterior capsule wrinkles were assessed by light microscopy. The mean scores between groups were statistically compared by means of the Mann-Whitney test.