The size of subconjunctival preparation does not influence the outcome of trabeculectomy with mitomycin C.
To compare the outcome of fornix-based trabeculectomy with mitomycin C (MMC) using 2 different sizes of subconjunctival preparation (36 mm² compared with 72 mm²). Prospective, randomized interventional case series. Patients 18 to 85 years of age with open-angle glaucoma and progressive visual field defects under maximum tolerated medical therapy were randomized to undergo initial fornix-based trabeculectomy with MMC (0.2 mg/mL for 5 min) with subconjunctival preparation of 6×6 mm (group A) or 8×9 mm (group B). Main outcome parameters were: intraocular pressure (IOP), best-corrected visual acuity (BCVA), number of 5-fluorouracil (5-FU) injections, and laser suturolyses (SL). Twenty-eight eyes of 26 patients were enrolled, including 14 eyes in group A and 14 in group B. At 12 months, IOP (mean±SD) was 9.69±2.5 mm Hg in group A and 9.93±3.2 mm Hg in group B (P=0.17) without glaucoma medication. Mean BCVA (logMAR) at month 12 was 0.29±0.26 in group A and 0.26±0.2 in group B (P=0.71). Patients required 3.0 5-FU in group A and 4.1±2.9 5-FU in group B (P=0.16); 1.3±1.1 SL and 1.8±1.1 SL, respectively (P=0.23). We noted 2 cases of intraocular hypotony in the 6×6 mm group (14.3%) and 1 in the 8×9 mm group (7.1%). There were no significant differences between study groups in mean IOP reduction, change in BCVA, or number of applied 5-FU and SL at 1-year follow-up. The area of subconjunctival preparation is only one of several factors playing a role in the outcome of trabeculectomy with MMC.