Acute primary angle closure: Configuration of the drainage angle in the first year after laser peripheral iridotomy

Abstract

Purpose To evaluate the changes in the configuration of the drainage angle in the first year after acute primary angle closure (APAC). Design Prospective observational case series. Participants Forty-four Asian subjects with APAC. Methods Acute primary angle closure cases were treated with medical therapy followed by laser peripheral iridotomy (LPI). Static and dynamic gonioscopies were performed in APAC-affected and fellow eyes before LPI (baseline) and then at 2 weeks, 4 months, and 12 months after presentation. The angles were graded in each quadrant according to the Shaffer scheme, and the number of clock hours of peripheral anterior synechiae (PAS) was recorded. Patients who underwent intraocular surgery at any point during follow-up were excluded from the study. Intraocular pressure (IOP) and medical treatment were documented at each visit, and gonioscopic changes were correlated with the development of elevation in IOP requiring medical treatment. Main outcome measures Average Shaffer grade and the number of clock hours of PAS. Results The majority of subjects were Chinese (84%) and female (64%), and the mean age was 60.2±10.7 years. At presentation, 73% of both affected and fellow eyes had very narrow angles (average Shaffer grade ≤ 1), with affected eyes having more extensive PAS ( P<0.001), a third of whom had ≥8 clock hours of PAS. In APAC eyes, there was a significant increase in angle width from baseline to 2 weeks after LPI ( P = 0.045), but no change in angle width subsequently. Fellow eyes showed a widening of the angle between baseline and week 2 ( P = 0.01) and from week 2 to month 4 ( P = 0.001). There was no significant change in PAS in either affected or fellow eyes over the 12 months of follow-up. Of the 44 subjects, 19 (41.3%) subsequently developed IOP elevation during follow-up that required treatment. However, there was no difference in angle width or amount of PAS between eyes with and without a subsequent rise in IOP, and the angle configuration did not change significantly in either group over 1 year. Conclusion In Asian eyes with APAC, the angle widened in the first 2 weeks after LPI, but did not change thereafter over 1 year, and the amount of PAS remained stable throughout. The results indicate the effectiveness of LPI in preventing progressive closure of the angle in the first year after APAC.