Chronic Angle Closure Glaucoma: The Relationship Between Disc Cupping, Intraocular Pressure and Angle Closure

Abstract

Abstract: : Purpose: This prospective observational study aimed to investigate the relationship between the degree of angle closure with intraocular pressure (IOP) and optic disc cupping in subjects with chronic angle closure glaucoma (CACG). Methods: 275 Asian subjects aged 18 or older with unilateral or bilateral CACG were included in this study. CACG was defined as the presence of glaucomatous optic neuropathy (with or without a visual field defect), a non–visible pigmented trabecular meshwork for at least 180 degrees on gonioscopy, presence of peripheral anterior synechiae (PAS) and an IOP > 21 mm Hg. For each patient, static and dynamic gonioscopy were performed and the angles were graded using the Shaffer’s system. IOP, the number of clock hours of PAS and vertical cup–disc ratio (CDR) were also recorded. Results: Mean age was 62.9 ± 9.4 years. 75% of patients were female. Mean angle width was 0.77 ± 0.53 and the mean number of clock hours of PAS was 4.77 ± 3.2. IOP (without treatment) correlated with angle width (r = –0.23, p < 0.001) and clock hours of PAS (r = 0.22, p < 0.001). Vertical CDR also correlated with angle width (r = –0.17, p = 0.004) and PAS (r = 0.28, p = < 0.001). Multiple linear regression using baseline IOP as the outcome variable showed a 0.39 (95% CI 0.15–0.63) mm Hg increase in baseline untreated IOP for each unit increase in clock hours of PAS (p = 0.002). Conclusions: In patients with CACG, higher untreated IOP and a larger vertical cup–disc ratio are associated with a narrower angle and greater extent of PAS.

Keywords: intraocular pressure • optic disc • outflow: trabecular meshwork