Risk factors of recurrence of macular oedema associated with branch retinal vein occlusion after intravitreal bevacizumab injection

Background/aims: To identify risk factors of recurrence of macular oedema in branch retinal vein occlusion (BRVO) after intravitreal bevacizumab (IVB) injection. Methods: The records of 63 patients who underwent IVB injection for macular oedema secondary to BRVO with at least 6 months of follow-up were reviewed. Patients were evaluated at baseline with fluorescein angiography (FA), optical coherence tomography (OCT) and ultra-wide-field fundus photography (WFP). During follow-up, OCT and WFP were repeated. The area of retinal haemorrhage, central retinal thickness (CRT), area (mm 2) of capillary non-perfusion within the 1 mm (NPA1), 1-3 mm and 6 mm zones of the ETDRS circle, foveal capillary filling time, degree (°) of foveal capillary network destruction and FA pattern were analysed. Results: Macular oedema recurred in 41 of 63 (65.1%) eyes after initial IVB injection. A binary logistic regression model showed that NPA1 (OR=434.97; 95% CI=5.52 to 34262.12, p=0.006) and initial CRT (OR=1.004; 95% CI=1.000 to 1.008, p=0.015) were significantly associated with the recurrence of macular oedema. Receiver operating characteristic curve analysis identified an NPA1 of 0.36 mm 2 (AUC: 0.735, sensitivity: 70.7%; specificity: 63.6%) and an initial CRT of 570 μm (AUC: 0.745, sensitivity: 63.4%; specificity: 77.3%) as cut-off values for predicting recurrence of macular oedema. Conclusions: Patients with BRVO with non-perfusion of more than half of the 1 mm zone of the ETDRS circle or with an initial CRT >570 μm should be closely monitored for macular oedema recurrence within 6 months of IVB injection.