Novel Optical Coherence Tomography Angiography Biomarker in Branch Retinal Vein Occlusion Macular Edema

Purpose: To evaluate the association between deep-superficial flow ratio (DSFR) and the treatment response of macular edema in branch retinal vein occlusion. Methods: Thirty eyes from 30 patients with branch retinal vein occlusion who had received optical coherence tomography angiography examination were included. Seventeen normal fellow eyes acted as the control group. Patients were classified into the "good response group" and the "refractory group" by absence or presence of macular edema after 6 months of treatment. The DSFRs were calculated by dividing deep capillary plexus vessel density by superficial capillary plexus vessel density on optical coherence tomography angiography. Results: The DSFR was 1.00 (SD ± 0.05) over parafoveal area in the control group. Among branch retinal vein occlusion eyes, parafoveal DSFR remained stable in the good response group (P = 0.822) and significantly decreased in the refractory group (P = 0.002). The DSFRs in the most severe nonperfusion area were significantly lower in the refractory group than in the good response group (0.85 ± 0.13 vs. 1.01 ± 0.15, P = 0.004). The DSFR in the most severe nonperfusion area was associates with treatment response in multivariate logistic regression (P = 0.015). Conclusion: Deep-superficial flow ratio can represent the relative damage of deep capillary plexus to superficial capillary plexus. Decreased DSFR was found in branch retinal vein occlusion eyes with refractory macular edema.