Fundus Densitometry Findings Suggest Optic Disc Hemorrhages in Primary Open-Angle Glaucoma Have an Arterial Origin

PURPOSE: To analyze optic disc hemorrhages (DH) associated with primary open-angle glaucoma by quantifying their geometric profile and comparing their densitometry with hemorrhages from retinal vein occlusions (RVO) and retinal macroaneurysms (MA), which have venous and arterial sources of bleeding, respectively. DESIGN: Retrospective cross-sectional study. METHODS: SETTING: Massachusetts Eye & Ear. POPULATION: Fundus images of DH (n = 40), MA (n = 14), and RVO (n = 25) were identified. Patient clinical backgrounds and demographics were obtained. MAIN OUTCOME MEASURES: Grayscale pixel intensity units of hemorrhages and adjacent arteriole and venule over the same background tissue were measured. Densitometry differentials (arteriole or venule minus hemorrhage [Delta A and Delta V, respectively]) were calculated. The ratios of length (radial) to midpoint width for DH were calculated. Mean Delta A and Delta V between groups were compared with t tests. Multiple linear regression assessed the relation of retinal hemorrhage diagnosis to Delta A and Delta V and of DH shape to Delta A and Delta V. RESULTS: Mean (+/- standard deviation) Delta A and Delta V for DH (6.9 +/- 7.1 and -4.7 +/- 8.0 pixel intensity units, respectively) and MA (5.3 +/- 5.9 and -6.0 +/- 4.6, respectively) were comparable (P >= .43). Mean Delta A (14.6 +/- 7.7) and Delta V (6.4 +/- 6.3) for RVO were significantly higher compared to DH and MA (P <.0001) and remained significant in multivariable analyses. A unit increase in DH length-to-width ratio was associated with 1.2 (0.5) and 1.3 (0.5) pixel intensity unit (standard error) decrease in Delta A and Delta V, respectively (P <=.014). CONCLUSIONS: DH have densitometry profiles comparable to MA and different from RVO, suggesting that DH in glaucoma have an arterial origin. (C) 2018 Elsevier Inc. All rights reserved.