Longitudinal Changes in Retinal Nerve Fiber Layer Thickness after Acute Primary Angle Closure Measured with Optical Coherence Tomography

PURPOSE. Longitudinal follow-up of peripapillary retinal nerve fiber layer (RNFL) thickness after an episode of acute primary angle closure (APAC) using Stratus optical coherence tomography (OCT). METHODS. Seventeen patients who had experienced a single unilateral APAC episode (intraocular pressure, >50 mm Hg) were enrolled. The average and superior, temporal, inferior, and nasal quadrant RNFL thicknesses of the affected and fellow eyes at 1, 4, and 12 weeks after remission were compared by using StratusOCT. The relationship between average RNFL thickness and interval of follow-up were evaluated with regression analysis. RESULTS. The mean duration of the APAC episode was 13.8 hours (range, 3-40). Comparison of the average and four quadrant RNFL thicknesses in the affected eyes longitudinally showed significant differences between 1 and 4, and 1 and 12 weeks, but not between 4 and 12 weeks. The average and four-quadrant RNFL thicknesses for the affected eyes were greater than the analogous values for fellow eyes at 1 week. In contrast, the inferior- and superior-quadrant RNFL thicknesses for the affected eyes were lower at 4 and 12 weeks, whereas the average and nasal quadrant values for the affected eyes were lower than those in fellow eyes at 12 weeks. Average RNFL thickness for the affected eyes was correlated with the interval of follow-up by using inverse regression analysis (P < 0.001; R 2 = 0.60). Controlling for duration of APAC episode, the interval of follow-up on RNFL thickness reduction remained significant (P < 0.001, r = -0.69). CONCLUSIONS. This study demonstrated an initial increase in diffuse RNFL thickness after a single APAC episode, followed by a subsequent decrease.