Ciliary body toxicity of subconjunctival suramin compared with mitomycin-C in the rabbit eye: determining the toxic concentration.

BACKGROUND/AIMS: To evaluate the safety of suramin compared with mitomycin-C (MMC) as an adjunctive agent in trabeculectomy by determining its ciliary body toxicity at predetermined effective dosages in rabbit eyes.

METHODS

Thirty-two New Zealand albino rabbits received either suramin (200, 300, 400, or 800 mg/ml) or MMC (0.2, 0.3, 0.4, or 0.8 mg/ml) injections subconjunctivally in the right eye. Enucleations were performed on the 1st, 3rd, 7th and 28th day. Untreated left eyes were injected with balanced salt solution and served as controls. The injection-exposed ciliary body specimens were processed to be investigated under the light microscope and transmission electron microscope.

RESULTS

There was no pathologic abnormality in specimens under light microscopy. The morphologic evaluation with transmission electron microscopy showed severe changes in structure, except for eyes treated with 200 mg/ml suramin and 0.2 mg/ml of MMC. These changes were more prominent in eyes exposed to MMC, and appeared earlier compared to suramin-treated eyes.

CONCLUSIONS

Suramin 200 mg/ml and MMC 0.2 mg/ml seem to be comparatively nontoxic to the ciliary body of the rabbit eye. Concentrations higher than these values caused severe damage.