Apoptotic cell death in rabbit lens after lens extraction.

PURPOSE To determine whether apoptosis or necrosis of lens epithelial cells occurs after lens extraction. METHODS Lens extraction was performed on 24 rabbit eyes. The authors then performed terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) and transmission electron microscopy on the eyes 1 to 10 days after surgery. RESULTS The postoperative lens was demarcated into three regions by the adhesion between the incised edge of the anterior capsule and the posterior capsule: the adhesive region, the intracapsular region, and the central portion of the posterior capsule. By day 2, TUNEL-positive cells with morphologic characteristics of necrosis were detected in the intracapsular region. Beginning on day 5, TUNEL-positive cells with morphologic characteristics of apoptosis and necrosis were detected in the adhesive region. Apoptotic cell death in this region was detected among the myofibroblast-like cells. Lens epithelial cells that had extended onto the central portion of the posterior capsule began to diminish on day 8 or 9, some of them morphologically demonstrating necrotic changes. CONCLUSIONS Apoptosis of lens epithelial cells occurs in the process of wound healing and reepithelialization after lens extraction, leading to secondary cataract. If the induction of apoptosis is better understood, protocols might be developed that could prevent reepithelialization through apoptosis, thus delaying or preventing secondary cataracts.