Endothelial changes in galactose-fed dogs

Specular microscopic studies indicate that the size (polymegathism) and shape (pleomorphism) of the hexagonal corneal endothelial cells change in diabetics. Similar morphometric changes of the corneal endothelium have also been experimentally observed in diabetic rats as well as in diabetic and galactose-fed dogs and concomitant administration of aldose reductase inhibitors reduced these morphological changes. The purpose of this study was to examine whether corneal endothelial changes in galactose-fed dogs are reversible by the marked reduction of galactitol production after stopping prolonged galactose feeding. Ten control dogs were fed a normal diet, while 48 dogs were fed a diet containing 30% galactose. The galactose diet was removed from 15 dogs after 24 months at which time pericyte ghosts in the retina had developed and another 15 dogs were removed from the galactose diet after 31 months when retinal microaneurysms had developed. Eighteen dogs remained on galactose diet throughout the study (38 months). Specular microscopy was conducted on members of all groups after 38 months of study and the photographs were analyzed in masked fashion on the Bambi image analysis system. The evaluation of the corneal endothelial cells revealed significant differences in the cell size and density between galactose-fed dogs in the three groups and normal, age-matched control dogs. Corneal endothelial changes were not significantly reduced in dogs fed galactose for either 24 months or 31 months and then fed a normal diet for 14 and 7 months, respectively, indicating that amelioration of endothelial cell changes requires therapy prior to the advent of endothelial morphologic changes.