Objective: A retrospective cohort study was undertaken to evaluate and compare the long-term results of trabeculectomy in primary open angle glaucoma (POAG) and chronic primary angle closure glaucoma (CPACG) in an Asian population.

Methods: Yearly diurnal measurements of intraocular pressure (IOP), best-corrected visual acuity, optic disc and visual field records of patients having primary adult glaucomas who had undergone trabeculectomy, without anti-mitotic agents, with a minimum of 5 years follow up were evaluated. Only one eye of each patient was studied. The success rates for IOP control in POAG and CPACG were statistically analysed.

Results: Sixty-four eyes of 64 patients were studied. The overall probability of success of trabeculectomy in controlling IOP to < or = 21 mmHg with or without additional topical antiglaucoma medication was 0.94 and 0.88 at 5 and 10 years, respectively. There was no statistically significant difference in the qualified and absolute success rates for IOP control between POAG and CPACG eyes (log rank test P= 0.6, 0.88, respectively). Twelve of 38 CPACG eyes had a two-line decrease in visual acuity as compared to four of 26 POAG eyes (P = 0.17). Progression or development of a cataract was the most common cause of visual decline.

Conclusions: Trabeculectomy without antimetabolite use appears to be efficacious in lowering IOP and in visual field preservation over a period of 10 years in both POAG and CPACG. Development/progression of cataract especially in eyes with chronic angle closure glaucoma after trabeculectomy must be considered an important issue.