Risarestat inhibits the accumulation of dulcitol in a dose-dependent manner, except for the 1.0% solution which has an activity comparable to the 0.25% solution. Risarestat peaks in the corneal epithelium, stroma, endothelium and aqueous humor in 30 minutes following instillation, then gradually diminishes time-dependently over a period of 24 hours. Risarestat remains detectable in the lens up to 24 hours, with a peak concentration at 2 hours after instillation. The anterior surface area of superficial cells in the group treated with Risarestat is significantly decreases from a mean value of 881 to 728 microns ² . Corneal sensitivity significantly improves from 5.36 to 1.37 g/mm ² . Animals treated with Risarestat shows a significant increase in the mean blinkresponse compared to untreated galactose-fed rats and does not differ significantly from controls towards the completion of the 7 month study. Animals treated topically with Risarestat and untreated galactose-fed rats develop bilateral nuclear cataracts within 3 weeks.