Dose-response characteristics of galactose-induced cataract in the rat.

The onset and progression of cataract was investigated in weanling Sprague-Dawley rats fed 10, 15, 20 and 30% dietary galactose (groups 1-4) for 45-226 days. Cataracts were graded on a 0-5 scale. After 226 days, 9% of the rats fed 10% galactose developed lesions beyond the very early stage of cataractogenesis (grade 1). After 154 days 50% of the rats fed 15% galactose developed subcortical cataract (grade 3) with no nuclear cataract. In the rats fed 20% galactose, an initial rapid development by 31 days of a grade 3 cataract was observed in 50% of the eyes. Advancement to grade 4 and grade 5 cataract proceeded more slowly; by 207 days, 45% of the eyes had grade 5 cataract. In rats fed 30% galactose, rapid vacuolization and development of nuclear cataracts (grade 5) were observed by day 44. Dietary galactose at levels of 20 and 30% was associated with a significant reduction in weight gain at the early stage of dietary treatment. These observations demonstrate that 10-30% dietary galactose induces cataract in rat lens in a dose- and time-dependent fashion. These data serve to further establish this animal model as a useful model for studying the sequelae of cataractogenesis.