Configuration of the drainage angle, intraocular pressure, and optic disc cupping in subjects with chronic angle-closure glaucoma.

Objective: To investigate the relationship between drainage angle configuration with untreated intraocular pressure (IOP) and optic disc cupping in subjects with chronic angle-closure glaucoma (CACG).

Design: Prospective, observational study.

Participants: Two hundred seventy-five Asian subjects with CACG who participated in a randomized controlled trial that investigated the IOP-reducing effect of latanoprost and timolol.

Methods: Chronic angle-closure glaucoma was defined as the presence of glaucomatous optic neuropathy (with or without a visual field defect), an anterior chamber angle in which the pigmented trabecular meshwork was not visible for at least 180 degrees on gonioscopy, and evidence of peripheral anterior synechiae (PAS) in association with elevated IOP of 21 mmHg or more. Static and dynamic gonioscopy were performed, the angles were graded in each quadrant according to the Shaffer scheme, and the number of clock hours of PAS was recorded. The untreated IOP and vertical cup-to-disc ratio were correlated with mean angle width and extent of PAS.

Main Outcome Measures: Mean angle width, clock hours of PAS, IOP, and vertical cup-to-disc ratio.

Results: Most subjects were female (75%), and the mean age was 62.9+/-9.4 years. The mean angle width was 0.77+/-0.53 and the mean number of clock hours of PAS was 4.77+/-3.2 hours. Untreated IOP correlated with angle width (r = -0.23; P<0.001) and clock hours of PAS (r = 0.22; P<0.001). Vertical cup-to-disc ratio also correlated with angle width (r = -0.17; P = 0.004) and PAS (r = 0.28; P<0.001). Performing a multiple linear regression using baseline IOP as the outcome variable with age, gender, clock hours of PAS, and angle width as predictors, there was a 0.39-mmHg (95% confidence interval, 0.15-0.63) increase in baseline untreated IOP for each unit increase in clock hours of PAS (P = 0.002).

Conclusions: In subjects with CACG, the extent of PAS and a narrower width of the drainage angle were associated with higher untreated IOP and a larger vertical cup-to-disc ratio.