Changes in Optic Nerve Head Vessel Density After Acute Primary Angle Closure Episode

PURPOSE. To evaluate the changes in circumpapillary vessel density (cpVD) and retinal nerve fiber layer (RNFL) thickness after an acute primary angle closure (APAC) episode. METHODS. Twenty-eight patients (28 pair of eyes) with unilateral APAC and 39 normal subjects (64 eyes) were included in this prospective, observational study. cpVD as measured by optical coherence tomography angiography and RNFL thickness as measured by spectral-domain optical coherence tomography were compared at 6 weeks after an APAC episode between affected, unaffected, and normal eyes. cpVD and RNFL thickness at 1 week and 6 weeks after APAC were also compared in APAC eyes in qualified images. RESULTS. At 6 weeks, cpVD was significantly lower in APAC eyes (57.3% +/- 6.8%), compared to fellow eyes (63.1% +/- 3.5%) and control eyes (63.6% +/- 3.4%) (P < 0.001). There was diffuse microvascular dropout with greater vessel density loss in the superonasal sector. APAC eyes had thinner RNFL globally and in each sector (except temporal and nasal sectors) than in fellow and normal eyes at 6 weeks. cpVD in the affected eyes was significantly greater at 1 week (56.3% +/- 5.3%) than values at 6 weeks (53.5% +/- 7%) (P = 0.003) but less than cpVD in the fellow eyes (62.4% 6 5.0%) (P < 0.001). RNFL thickness for the APAC eyes at 1 week (120.6 V 18.0 mu m) was greater than the analogous values for affected eyes (90.1 +/- 13.2 mu m; P = 0.037) and fellow eyes at 6 weeks (102.5 +/- 5.7 mu m; P = 0.001). CONCLUSIONS. Vessel density decreased over 6 weeks after an APAC episode compared with the contralateral unaffected eyes. In contrast, there was an initial increase in RNFL thickness that was followed by a subsequent decrease.