The effect of brief intrascleral or episcleral application of mitomycin C on the ciliary epithelium and pressure in the rabbit eye.

Ten albino rabbits underwent bilateral Cairns' trabeculectomy (group 1). A sponge soaked with 0.5 mg/ml mitomycin C solution was applied under the scleral flap for 5 min followed by irrigation with 20 ml 0.9% sodium chloride solution in the left eyes. In the right eyes a sponge soaked with 0.9% sodium chloride solutions was applied. In 9 albino rabbits a 3 x 2 mm episcleral area at 12 o'clock position was exposed to 0.5 mg/ml mitomycin C solution on one side and to 0.9% sodium chloride solution in the contralateral eye (group 2). Five, 10 and 30 days (group 1 and 2) and 3 months (group 1) following surgery specimens of the ciliary body adjacent, beside and opposite to the site of the operation were excised and studied with light and electron microscopy. No stromal or epithelial morphological changes of toxic origin have been revealed in the ciliary processes, even in specimens adjacent to the surgical area. In 5 albino rabbits (group 3) intraocular pressure was recorded before surgery and 5, 10 and 30 days after unilateral, episcleral mitomycin C application described in group 2. No significant changes or interocular difference has been recorded. The results suggest that long-term postoperative hypotony following trabeculectomy with mitomycin C is not caused by reduced aqueous humour secretion of toxic origin.