Inhibition of experimental diabetic cataract by topical administration of RS-verapamil hydrochloride

Aim: To investigate the efficacy of verapamil eye drops for inhibition of diabetic cataract in rats. Methods: Diabetes was induced in 69 male Sprague-Dawley rats by an intraperitoneal injection of streptozotocin ( 65 mg/ kg body weight). One group ( DV) of animals was treated by instillation of one drop of 0.2% RS-verapamil hydrochloride in both eyes three times daily for 8 weeks. The placebo treated group ( D) received the vehicle solution only. After 8 weeks the lenses were removed, inspected, and photographed using bright and dark field illumination. The transmission of He-Ne laser light was measured in the optical axis of each lens in order to determine the turbidity coefficient (t) as a measure of central lens opacity. Following digital image analysis, the integrated density as a measure of central and mid-peripheral opacities was determined. Results: Lenses of both groups developed peripheral cortical opacities not affecting the optical axis. Advanced and paracentral cortical opacities were present in 10 (16.7%) of the placebo treated lenses ( D) and two (3.8%) of the verapamil treated lenses ( DV). Complete corticonuclear cataract developed in four (6.7%) of the lenses from group D but none of the lenses from group DV. The mean lens turbidity t was determined to be 0.019 (SEM 0.002) mm(-1) (n = 52) in the verapamil treated diabetic rats (DV) and 0.042 (0.008) mm(-1) (n = 60) in the placebo treated group ( D). This difference was statistically significant ( p = 0.0054). The mean integrated density was 274.91 (22.5) in group D (n = 60) and 196.28 (20.7) in group DV (n = 37). This difference was also significant (p = 0.0037). Conclusion: Verapamil eye drops 0.2% administered three times daily are effective in inhibiting the progression of lens opacities in streptozotocin diabetic rats.