Differences in naphthalene cataract formation between albino and pigmented rat eyes.

The progression of naphthalene cataracts induced in Brown-Norway rats and Sprague-Dawley rats was compared. The quality of lens changes was basically the same in both strains. However, the cataract progression in Brown-Norway rats showed regularity and was fast as compared with the progression in Sprague-Dawley rats. The cataract development could be divided into three stages. Stage 1: formation of water clefts below the anterior lens capsule (shallow cortex) was observed as the initial change; stage 2: these water clefts extended into the deeper cortical layers, and a semicircular opaque band at the deeper cortical region becomes visible; stage 3: a retroillumination image revealed a ring shadow formation - slit image observation showed wedge-shaped cortical and deeper cortical zonular opacification as the final stage. The expression of these three stages in Sprague-Dawley rats is less uniform and timely delayed as compared with Brown-Norway rats.