Abstract: Objective To compare the 18 months results of initial trabeculectomy in patients with chronic angle closure glaucoma (CACG) with acute attack with those without acute attack.  Design Prospective comparative case series. Participants 48 CACG patients with acute attack (48 eyes) (acute attack group) and 101 CACG patients without acute attack (101 eyes) (without acute attack group) from 4 ophthalmic centers were included retrospectively.  Methods All patients underwent trabeculetomy and follow-up for 18 months. Visual acuity (VA), intraocular pressure (IOP), medication and complications for baseline and postoperation (postoperation 1, 3 days, 1, 2 weeks, 1, 3, 6, 12, 18 months) were recorded. Complete success was defined as IOP was less than 21 mmHg without any medication at the final visit. Main Outcome Measures IOP, changes of VA (VA at final visit-VA at baseline visit), IOP fluctuation (IOP standard deviation during follow-up), success rate. Results Change of VA in acute attack group and without acute attack group was -0.06±0.47 and 0.02±0.36, respectively (P=0.166). Mean IOP during follow-up in acute attack group and without acute attack group was 14.9±4.0 mmHg and 14.6±2.8 mmHg, respectively (P=0.601). Long term IOP fluctuation was not significantly different between acute attack group and without acute attack group （P=0.452）, which was 3.1±2.5 mmHg and 2.8±1.6 mmHg, respectively. The IOP at postoperation 18 months in acute attack group and without acute attack group was 16.8±7.5 mmHg and 15.4±4.0 mmHg, respectively（P=0.259）. The success rate of the trabeculectomy was better in without acute attack group (93.1%) than that in acute attack group (85.7%), however, the difference between two groups was not significant （x²=2.11， P=0.146）. Conclusion The success rate of the trabeculectomy was similarly high in both acute attack group and without acute attack group.

Key words:  primary angle closure glaucoma/surgery, trabeculectomy, acute attack