OCULAR TOXICITY OF MITOMYCIN-C AND 5-FLUOROURACIL IN THE RABBIT

We studied the histotoxic effects of mitomycin C and 5-fluorouracil (5 -FU) in the eyes of New Zealand white rabbits using light microscopy, Twenty-four eyes of 24 rabbits received subconjunctival injections of mitomycin C (0.025, 0.05, 0.10, 0.20, 0.40 or 0.80 mg/mL) or 5-FU (10. 0 mg/mL), either alone (0.25 mL,) or in combination with anterior cham ber injections (0.05 mL), once daily for 4 consecutive days. Two eyes of two rabbits received subconjunctival and anterior chamber injection s of unpreserved sterile saline. The eyes were examined regularly for external signs of toxicity and were enucleated 4 weeks after the last injection. Mitomycin C produced considerable tissue damage in the ante rior segment, the severity being related to both the concentration and the route of administration. Eyes that received both subconjunctival and anterior chamber injections showed more damage than those that rec eived subconjunctival injections alone, At the highest concentration o f mitomycin C the cornea was inflamed, with stromal necrosis and marke d endothelial loss. Hemorrhagic iris necrosis was also seen. in contra st, the 5-FU-treated eyes showed no microscopic evidence of toxicity. We conclude that there is greater risk of toxic anterior segment effec ts when mitomycin C is used as adjunction therapy following filtration or pterygium surgery.