ULTRASTRUCTURAL-CHANGES IN RABBIT CILIARY BODY AFTER EXTRAOCULAR MITOMYCIN-C

PURPOSE. To study the ultrastructural changes in ciliary body epitheli um of the rabbit eye after subconjunctival injections of mitomycin C. METHODS. One eye of six New Zealand white rabbits was given a subconju nctival injection at the 12-o'clock position with 0.005, 0.02, 0.08, 0 .1, 0.12, or 0.16 mg mitomycin C. The fellow eye was given a subconjun ctival injection of balanced salt solution. Two weeks after treatment, the eyes were enucleated, and the ciliary body was exposed and submer ged in fresh 4% paraformaldehyde/2% glutaraldehyde in 0.1 M phosphate buffer, pH 7.4, at 4 degrees C. Electron microscopy of the ciliary bod y was performed at two sites: the injection site (12-o'clock position) and 180 degrees away (6-o'clock position). RESULTS. At dosages of 0.1 mg and higher, ciliary body epithelial cells beneath the injection si te were thinned. There were vacuoles and expansion of intracellular an d intercellular spaces. Plasma membrane infoldings were disrupted, and the apical membrane was thinned. Mitochondria and nuclei were normal. Ciliary body epithelium at 6-o'clock position showed only mild archit ectural distortion of the plasma membrane infoldings. Eyes that receiv ed lower doses of mitomycin C (0.005 mg, 0.02 mg, and 0.08 mg) and bal anced salt solution showed normal ciliary body epithelium at the injec tion site and 180 degrees away. CONCLUSIONS. Subconjunctival injection of mitomycin C in the rabbit produces dose-dependent localized ultras tructural changes of the ciliary body epithelium.