EFFECTS OF MITOMYCIN-C ON THE RAT RETINA

To evaluate the retinal toxicity of mitomycin C injection in the rat e ye, we conducted an electroretinographic study and a histopathologic s tudy. Three different concentrations of mitomycin C (0.2, 0.3 and 0.4 mg/ml) were injected into either the Vitreous cavity or the anterior c hamber of the experimental eyes. A full-field electroretinogram was re corded before injection and 2, 4 and 7 days after injection. The retin as of all eyes were examined by light and electron microscopy. We foun d no evidence of electroretinographic and histologic changes 2 and 7 d ays after injection of 0.4 mg/ml of mitomycin C into the anterior cham ber. However, profound electroretinographic changes did follow injecti on of the drug into the vitreous. These were absent with the 0.2-mg/ml solution at 7 days, mild with the 0.3-mg/ml solution at 7 days and pr ofound with the 0.4-mg/ml solution as early as 2 days. Intravitreal in jection of 0.4 mg/ml, however, showed selective degeneration of muller cell process at Flay 2, retinal pigment epithelium changes at day 4 a nd irregular arrangement of the outer nuclear layer and photoreceptors at day 7. Intravitreal injection of mitomycin C in a concentration co mparable to the one used clinically could cause retinal disorders, bot h functionally and histologically.