Prolonged antiscarring effects of ilomastat and MMC after experimental glaucoma filtration surgery

PURPOSE: To determine the long-term antiscarring effect of ilomastat treatment after experimental glaucoma filtration surgery (GFS). METHODS: In a randomized, prospective, masked-observer study, 21 New Zealand White rabbits underwent modified GFS. The animals were allocated to receive either intraoperative mitomycin-C (MMC) at a concentration of 0.2 mg/mL or postoperative subconjunctival injections of either ilomastat or phosphate-buffered saline (PBS). Fifteen injections were given to each animal during the study period. The animals were killed 60 days after surgery. Bleb morphology and intraocular pressures were recorded. Tissue sections were immunohistochemically stained for signs of scarring. RESULTS: Ilomastat significantly improved surgical outcome compared with vehicle (P < 0.0163) and length of bleb survival was similar to the MMC group. The mean day of failure was 46.2 (range, 42-60) with ilomastat, 51.3 (range, 49-60) with MMC, and 16 (range, 15-21) with vehicle. IOP maintenance with ilomastat was similar to that in the MMC group. Histologically, minimal scar tissue was seen with MMC and ilomastat. MMC-treated tissue demonstrated subconjunctival hypocellularity associated with peripheral fibrosis. Ilomastat resulted in normal-appearing conjunctival morphology. CONCLUSIONS: Ilomastat successfully prolongs bleb survival. MMP inhibition may provide an additional, potentially safer method of controlling intraocular pressure, thus preventing failure of glaucoma surgery, and may also act as a potential adjuvant treatment when MMC alone is inadequate.