Acute Primary Angle Closure Attack Does Not Cause an Increased Cup-to-Disc Ratio

Abstract

To determine if an increased cup-to-disc ratio (CDR) and retinal nerve fiber layer (RNFL) loss occur after acute primary angle closure (APAC). Prospective, observational case series. Twenty participants with unilateral APAC provided 20 affected eyes and 20 fellow eyes (controls) for analysis. After initial presentation, participants attended 3 further assessments over a 12-month period (visit 2, within 2 weeks; visit 3, 2-3 months; and visit 4, 6-12 months), in which they underwent the following investigations: Heidelberg Retinal Tomography (Heidelberg Engineering, Dossenheim, Germany), optical coherence tomography of the RNFL and macula, and automated perimetry. Cup-to-disc ratio, optic cup area, neuroretinal rim area, RNFL thickness, macular thickness, and volume. There was no change from visits 2 to 4 in CDR (0.46 ± 0.17 vs. 0.47 ± 0.20; P = 0.94), neuroretinal rim area (1.64 ± 0.55 vs. 1.64 ± 0.57; P = 0.96), or other optic nerve head parameters analyzed in eyes with APAC. The mean overall RNFL thickness decreased from 106.6 ± 17.9 μm to 92.9 ± 18.3 μm between visits 2 and 3 (P<0.01) in affected eyes. The superior quadrant RNFL thickness decreased from 134.8 ± 25.9 μm to 113 ± 25.7 μm (P<0.01), and the inferior quadrant RNFL thickness decreased from 139.1 ± 28.4 μm to 115.6 ± 24.9 μm (P<0.01). There was no significant change in macular thickness or volume. This study demonstrated that an increase in CDR does not occur after APAC that is treated promptly, although RNFL loss does occur.