EFFECTS OF TOPICALLY APPLIED MITOMYCIN-C ON INTRAOCULAR-PRESSURE, FACILITY OF OUTFLOW, AND FIBROSIS AFTER GLAUCOMA FILTRATION SURGERY IN CLINICALLY NORMAL DOGS

The effects of mitomycin-C on intraocular pressure (IOP), facility of outflow (C), and Tenon's capsule fibrosis were studied over 60 days in 10 clinically normal dogs. A 1-piece, silicone glaucoma implant was s urgically implanted into both eyes; the filtration site of one eye was treated with a single, 5-minute intraoperative application of mitomyc in (0.5 mg/ml), and the fellow eye was treated in a similar manner wit h balanced salt solution. There were no significant differences in pre operative IOP or C-values between treatment groups. Mean IOP in eyes o f both groups initially decreased from the preoperative value, but ret urned to the baseline value by day 21. Mean facility of aqueous outflo w (C-value) increased in all eyes during the first 14 days (mitomycin- C-value = 2.26 +/- 0.72; control C-value = 2.38 +/- 0.81), then reache d a plateau that was significantly higher than the baseline value in m itomycin (P = 0.039) and control (P = 0.041) eyes. Histologic evaluati on revealed all implants surrounded by a connective tissue capsule com posed of regular dense collagen and fibroblasts that was significantly (P = 0.003) thinner in the mitomycin-treated (scleral side = 167 +/- 62 mu m; conjunctival side = 122 +/- 41 mu m) than the control (sclera l side = 261 +/- 92 mu m; conjunctival side = 180 +/- 48 mu m) group. There were, however, no significant differences in IOP or C-values bet ween groups at any postoperative time interval. Results of this study indicate that intraoperative treatment with mitomycin suppresses, but does not prevent fibrosis around silicone filtering implants.