A novel high resolution in vivo digital imaging system for the evaluation of experimental cataract in diabetic rats

The purpose of this study was to establish a novel imaging system for evaluation of cataract in small animals. Diabetic cataract was induced in male Wistar rats by a combination of a bolus injection of streptozotocin (65 mg/kg, i.v.) and 5% D-glucose given as drinking water. To assess cataract development, we designed a digital camera system equipped with a non-reflecting illuminator for capturing clear high-resolution full lens images in the horizontal plane. Cataract was evaluated from the resulting images using both an observer-based scoring system and quantitative digital image-analysis techniques. The onset of cataract was detected in the peripheral section of the lens in 57% of cases 2 weeks after induction of hyperglycemia. Central opacities were visible following 3 weeks in hyperglycemic conditions. The cataract increased in severity with time, so that by week 9 in hyperglycemic conditions, mature cataracts were developed in over 90% of lenses. Treatment of diabetic rats with GP-1447, an aldose reductase inhibitor, completely prevented the formation of diabetic cataracts. These results indicate that the digital imaging system established in the present study permits an assessment of all stages of cataract development and it is helpful for accurately evaluating the effects of therapeutic drugs on cataracts.