Quadrant Asymmetry in Optical Coherence Tomography Angiography Metrics in Ischemic Versus Non-Ischemic Central Retinal Vein Occlusion Eyes

Purpose: To determine whether quadrant asymmetry (QA) of optical coherence tomography angiography (OCTA) metrics differs between non-ischemic versus ischemic central retinal vein occlusion (CRVO). Methods: Fifty-eight eyes (21 non-ischemic, 10 ischemic CRVO, and 27 contralateral control eyes) underwent 3 x 3 mm spectral-domain OCTA scans with quantification of the superficial retinal layer vessel length density (VLD) and perfusion density (PD). QA, defined as the maximum-minus-minimum value among four parafoveal Early Treatment Diabetic Retinopathy Study (ETDRS) quadrants, was compared by linear regression including fixed effects for each eye. Results: Mean age was 73.6 +/- 11.4 (range 39-88), 73.8 +/- 12.4 (range 39-91) and 77.2 +/- 9.83, (range 60-88); and QA was 3.46 +/- 1.76, 3.14 +/- 1.57, and 4.88 +/- 2.42 for VLD and 0.072 +/- 0.038, 0.062 +/- 0.036, and 0.11 +/- 0.056 for PD for control, non-ischemic, and ischemic, respectively. QA was significantly higher in ischemic (0.109 +/- 0.056) than non-ischemic CRVO eyes (0.062 +/- 0.036; P = 0.02) and control eyes for PD (0.072 +/- 0.038; P = 0.03). QA was also greater in ischemic (4.875 +/- 2.418) than non-ischemic CRVO (3.141 +/- 1.572) for VLD (P = 0.04). In terms of identifying which particular quadrant is most affected by ischemia, multivariate regression analysis comparing intra-quadrant effect on the presence of ischemia versus non-ischemia showed no quadrant was significantly affected (P > 0.05 for all quadrants). Conclusions: Ischemic CRVO increases intraeye QA of OCTA metrics when compared to non-ischemic CRVO and control eyes. No specific ETDRS quadrant appears to be more affected. Translational Relevance: This work uses an intraeye method to delineate between ischemic and non-ischemic CRVO by OCTA imaging, overcoming inter-eye variables encountered in clinical care.