To observe the value of optical coherence tomography (OCTA) in distinguishing ischemic and non-ischemic branch retinal vein occlusion (BRVO).

A prospective clinical observational study. From January 2020 to January 2021, 44 eyes of 44 patients with BRVO diagnosed in Tianjin Medical University Eye Hospital were included in the study. Among them, there were 24 eyes of 24 males and 20 eyes of 20 females. The macular edema subsided after three consecutive anti-vascular endothelial growth factor (VEGF) drug treatments. All the affected eyes underwent best corrected visual acuity (BCVA), intraocular pressure, ultra-wide-angle fluorescein fundus angiography (UWFFA), and OCTA examination. According to the results of UWFFA, the affected eyes were divided into ischemic group and non-ischemic group, with 22 eyes in 22 patients. The macular area of the affected eye with an OCTA instrument were scaned in the range of 3 mm× 3 mm to measure the blood flow density (SVD, DVD), foveal blood flow density (SFVD, DFVD), parafoveal blood flow density (SPFVD, DPFVD), affected hemilateral blood flow density (SHVD, DHVD) and affected quadrant blood flow density (SQVD, DQVD) of the superficial capillary layer (SCP) and deep capillary layer (DCP) of the retina, foveal retinal thickness (CRT), fovea avascular zone (FAZ) area, perimeter of FAZ (PERIM), out-of-roundness index (AI), and blood flow density within 300 μm width of FAZ (FD-300). The two-sample independent t test was used to compare the parameters between the ischemic group and the non-ischemic group. Receiver operating characteristic (ROC) curve analysis was used to measure the area under the curve (AUC) of blood flow density to predict ischemic BRVO, determine the critical value for predicting ischemic BRVO and the corresponding sensitivity and specificity, with AUC> 0.9 as the prediction performance was good.

The differences of BCVA (t=1.544), intraocular pressure (t=-0.404), SFVD (t=0.444), DFVD (t=-0.812), CRT (t=1.082), FAZ area (t=-0.785), PERIM (t=-0.685), AI (t=1.047) of the eyes in the ischemic group and non-ischemic group were not statistically significant (P>0.05). The differences of age (t=2.194), SVD (t=-3.796), SPFVD (t=-4.181), SHVD (t=-4.700), SQVD (t=-3.594), DVD (t=-2.324), DPFVD (t=-2.476), DHVD (t=-2.118), DQVD (t=-6.529) and FD-300 (t=-5.116) of the eyes in the ischemic group and non-ischemic group area were statistically significant (P<0.05). ROC curve analysis results showed that DQVD predicted the AUC of ischemic BRVO the largest (0.917), the best cut-off value was 33.75%, and the sensitivity and specificity were 90.9% and 81.8%, respectively.

OCTA can quantitatively assess the microvascular structure of SCP and DCP in the macular area of BRVO eyes, and contribute to distinguish ischemic and non-ischemic BRVO.

Retinal vein occlusion; Ischemia; Tomography, optical coherence; Regional blood flow