CONCANAVALIN A-INDUCED POSTERIOR SUBCAPSULAR CATARACT - A NEW MODEL OF CATARACTOGENESIS

Purpose. To evaluate the effect of Concanavalin A (Con A) on cataract formation in New Zealand Albino rabbits. Uveitis is a chronic inflamma tory condition of the eye involving the anterior and/or posterior segm ents. It may be acute or chronic and is associated with the developmen t of posterior subscapular cataract over time. Con A is a nonspecific inflammatory agent and mitogen for T cells and some B cells. Used exte nsively in immunogenic studies Con A has been shown to induce uveitis after intravitreal injection in New Zealand Albino rabbits. Methods. I n two separate studies, Con A was injected intracamerally or intravitr eally into one eye of 12 New Zealand Albino rabbits and an equal volum e of balanced salt solution was injected into the opposite eye as a co ntrol. In a third study, the effect of topical steroids after intravit real injection of Con A was evaluated. In all studies, anterior and po sterior inflammation and the development of cataract was monitored by slit lamp biomicroscopy and photography. Cataract formation was also s tudied histopathologically. Results. Initially, all eyes treated with Con A demonstrated moderate anterior chamber inflammation while eyes t reated with balanced salt solution showed no inflammation. Three month s after treatment, posterior subcapsular cataracts were present in all rabbit eyes treated with intravitreal Con A. In the third study, topi cal steroid treatment of Con A-induced inflammation significantly redu ced anterior chamber inflammation but had no effect on vitreous humor and posterior subcapsular cataract formation. Conclusion. This experim ental model was the first to demonstrate the development of posterior subcapsular cataracts after Con-A induced inflammation. The cataract w as clinically and histologically similar to human posterior subscapula r cataracts.