Assessing the role of subconjunctival versus intrascleral application of mitomycin C in high-risk trabeculectomies.

ABSTRACT

PURPOSE: To compare the efficacy and safety of subconjunctival and intrascleral applications of mitomycin C (MMC) in trabeculectomy for high-risk glaucomas. METHODOLOGY: A randomized prospective clinical study was conducted on 41 consecutive eyes with a high risk of glaucoma surgery failure. Patients were randomized to trabeculectomy and application of subconjunctival MMC or to trabeculectomy and application of intrascleral MMC. MMC solution 0.2 mg/ml was applied for 3 minutes under the conjunctival flap overlying the proposed site of trabeculectomy in Group I (n=21), or intrasclerally under the superficial scleral flap in Group II (n=20) RESULTS: After a follow-up of one year, the intraocular pressure (IOP) decreased from a mean basal IOP of 33.0 +/- 8.4 mm Hg to 12.56 +/- 2.54 mm Hg in Group I and from 30.9 +/- 6.6 mm Hg to 11.6 +/- 2.21 mm Hg in Group II. The IOP was 6-21 mmHg, without medication, in 90.5 % of the eyes in Group I and 75 % of the eyes Group II. Ocular hypotony, hypotony maculopathy, choroidal detachment and a shallow anterior chamber were more frequent with the intrascleral application of MMC during trabeculectomy, but the difference was not statistically significant. The overall success of the surgery at one year, i.e., achieving an IOP of 6-21 mmHg and a stable vision, (reduction in visual acuity of < or = 2 lines), was 90.5% in Group I and 75 % in Group II. CONCLUSION: No significant difference was seen in overall success or complication between subconjunctival and intrascleral application of MMC-augmented trabeculectomies in glaucomatous eyes at high risk of surgical failure.