An extraocular application of mitomycin C causes A localized dose-dependent ultrastructural change in the rabbit ciliary body epithelium

Purpose. To study the ultrastructural changes in ciliary body epithelium of the rabbit eye following sub-Tenon injections of Mitomycin C. Methods. One eye of six New Zealand white rabbits was given a sub-Tenon injection at 12 o'clock with 0.005, 0.02, 0.08, 0.1, 0.12 or 0.16 mg Mitomycin C. The fellow eye was given a sub-Tenon injection of saline. Intraocular pressures and clinical courses were followed for two weeks. Immediately following enucleation, the ciliary body was exposed and submerged in fresh 4% paraformaldehyde and 2% gluteraldehyde in phosphate pH 7.4 at 4 degrees C. Electron microscopy was performed at two sites, the injection sites and 180 degrees away (6 o'clock). Results. At dosages of 0.1 mg and higher, ciliary body epithelial cells at 12 o'clock were attenuated. There were vacuoles and expansion of intracellular and intercellular spaces. Basal infoldings were disrupted and the basal lamina was thinned. Mitochondria and nuclei were normal. Ciliary body epithelium at 6 o'clock showed only mild architectural distortion of the basal infoldings. Eyes receiving lower concentrations (0.005, 0.02, and 0.08 mg) Mitomycin C and BSS showed normal ciliary body epithelium. Intraocular pressures at two weeks were not statistically different from pre-injection pressures. Conclusions. Sub-Tenon injections of Mitomycin C in the rabbit produce dose-dependent, localized ultrastructural changes to the ciliary body epithelium.