A new approach against sugar cataract through aldose reductase inhibitors.

Aldose reductase inhibition is one of the therapeutic strategies that has been proposed to prevent or ameliorate long term diabetic complications including retinopathy and sugar cataract. Rats were fed with a galactose rich diet and the aldose reductase inhibitor Tolrestat was topically delivered by ocular instillation. The levels of lens aldose reductase activity, galactitol and the onset of cataract were evaluated during and after treatment with the inhibitor. Topical application of 1-3% Tolrestat (10 microl) four times daily resulted, after 9 days, in a significant decrease in the enzyme activity. Well after interrupting treatment with the drug, the enzyme activity remained impaired and galactose induced cataract was prevented. Our findings may represent the basis for therapeutic plans to prevent sugar cataract by long term cyclic treatments with aldose reductase inhibitors, with reduction in drug doses and side effects. Copyright 1999 Academic Press.