Abstract

I n diabetic and galactose-fed rats the appearance of a mature lens cataract, as a white opacity which is visible to the naked eye, is sudden and accompanied by striking physiologic and biochemical changes. 1 It is the purpose of this paper to present, in a graphic manner, the course of these changes during the cataractogenic period, plus additional new observations, so that trends and abrupt changes may be noted. Methods Mature cataracts were determined with the naked eye by observing the lens daily and noting the day on which the lens became opaque. In rats, this change is sudden and the day of onset of a mature cataract is readily determined. Diabetes was produced in 27 to 38-day-old male Sprague-Dawley rats by the intravenous injection of 50 mg. of alloxan monohydrate per kilogram of body weight. Only rats with average blood sugars above 400 mg. per cent were used. The average blood sugar was about 500 mg. per cent and the median time for mature cataract formation was 76 days. The galactose diet consisted of a mixture of 65 per cent ground chow and 35 per cent galactose. It was fed in unlimited amounts to male Sprague-Dawley rats having an initial age of 25 to 27 days. The median time for mature cataract formation was 18 days. The lenses were removed as previously described. 2 Individual lenses were macerated in 1 ml. of 2.0 per cent zinc sulfate and 1 ml. of 1.8 per cent barium hydroxide. The proteins were removed by centrifuging and 0.5 aliquots were used for determining reduced sugars, fructose, and glucose. Sorbitol and dulcitol were determined by the method of West and Rapoport 3 as modified by Faulkner 4 ; glucose by the oxidase method 5 ; and fructose by the method of Roe. 7 Results are reported as milligrams of the disodium salt per 100 Gm. of lens. The