To compare the long-term results of trabeculectomy and Ahmed glaucoma valve implant in the initial surgical management of primary open- and closed-angle glaucoma.

Randomized controlled clinical trial.

One eye each of consecutive patients with primary glaucoma and without prior intraocular surgery was randomized to receive either trabeculectomy or the Ahmed implant.

Large university-affiliated eye hospital in Columbo, Sri Lanka.

Of 123 patients, 64 were randomized to trabeculectomy and 59 to the Ahmed implant. With a mean follow-up of 31 months, the trabeculectomy group had statistically lower intraocular pressures (IOP) during the first postoperative year. After the first year, the IOPs were comparable. No statistically significant differences between groups were noted for postoperative visual acuity, visual field, anterior chamber depth, and short-term or long-term complications. Adjunctive medication requirement was comparable for both groups. The cumulative probabilities of success (IOP <21 mm Hg and at least 15% reduction in IOP from preoperative levels) at the final follow-up period (months, 41–52) were 68.1% for trabeculectomy and 69.8% for Ahmed implant (P = .86).

Lower IOPs were noted for the trabeculectomy group during the first year. With longer follow-up, the IOPs and the cumulative probabilities of success were comparable between the two groups.