Effectiveness of trabeculectomy with mitomycin C for glaucomatous eyes with low intraocular pressure on treatment eye drops

PURPOSE: To examine the efficacy and safety of current trabeculectomy with mitomycin C in Japan for glaucomatous eyes with low intraocular pressure (IOP). METHODS: Two hundred ninety‐four eyes of 294 patients with IOP ≤21 mmHg before surgery were studied; all patients were participants in the Collaborative Bleb‐related Infection Incidence and Treatment Study (CBIITS), a multicentre, prospective, cohort study conducted at 34 ophthalmological institutions throughout Japan. All eyes had an intraocular pressure ≤ 21 mmHg and had undergone trabeculectomy alone or phacotrabeculectomy. Two success criteria were used: Criterion A comprised 20% reduction of baseline IOP and Criterion B comprised 30% reduction of baseline IOP. The primary outcome was the success rate for each of these criteria. RESULTS: The qualified success rates were 87.3% for Criterion A and 42.0% for Criterion B at 5 years. Mean IOP was significantly reduced, from 16.7 ± 2.7 to 11.6 ± 4.0 mmHg at 5 years after trabeculectomy (p < 0.0001); the number of anti‐glaucoma medications significantly decreased from 2.7 ± 1.1 to 1.0 ± 1.2 (p < 0.0001) at 5 years after the surgery. Three or more trabeculectomies, and needling were related to increased risk of failure. Incidences of postoperative hyphema, infection, shallow anterior chamber and bleb leakage were 2.4%, 2.4%, 2.0% and 3.4%, respectively. CONCLUSIONS: This study showed that trabeculectomy with mitomycin C is an effective procedure with few surgical complications for reducing IOP in patients, even if preoperative IOP was within the normal range.