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 (degrees) 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 mm (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 mu m should be closely monitored for macular oedema recurrence within 6 months of IVB injection.