Response of the lens of the galactose-fed rat to YAG laser-induced injury.

Many investigations have focussed on the response of normal lenses to injury, but almost no attention in this regard has been given to the response of cataractous lenses. We addressed this subject, particularly in regard to cell proliferation, using 'cataractous' lenses from rats fed on a galactose-rich diet. Five days after initiation of the 50% D-galactose diet, the anterior aspects of the lenses of these animals were injured by Nd-YAG laser. For up to 5 additional days, the rats were maintained on a 25% D-galactose diet. Similarly injured, control animals were fed on 100% Purina laboratory chow throughout the experimental period. The response of the lenses to injury was assessed by gross examination and by light microscopic examination of paraffin sections and epithelial whole-mounts. By the second day post-injury, the anterior aspect of some of the lenses from galactose-fed rats was characterized by a band of darkly staining structures. Although the average number of mitotic figures of lenses from galactose-fed (GF) rats had increased by 2 days after injury, it still remained below that of injured lenses from normally fed rats. After 5 days, some of the eyes of galactose-fed rats were greatly swollen. At both 2 days and 5 days after injury, lenses of GF rats tended to be characterized by a greatly proliferated epithelium, destruction of lens fibers, and loss of cortical material. Responses of lenses from normally fed rats were far less dramatic. The results suggest that, in the case of lenses made cataractous by a galactose-rich diet, injury is more deleterious, and the response of epithelial cells more intense, than in normal lenses.