AIM:To evaluate the functional and structural changes of foveal macula after intravitreal ranibizumab injection in patients with macular edema secondary to branch retinal vein occlusion(BRVO-ME)and screen the factors that can predict the final visual acuity of the patients.

METHODS: Prospective, clinical study. In this prospective single-arm study, we observed 25 patients(25 eyes)diagnosed with BRVO-ME who were enrolled from 2018.6-2019.5 in the first central hospital of Baoding. All patients received monthly ranibizumab 0.5mg injections for 3 consecutive months. The best-corrected visual acuity(BCVA),the central macular thickness(CMT)and the vessel perfusion density(VPD), vessel length density(VLD)and fovea avascular zone(FAZ)of superficial capillary plexus(SCP)were evaluated detected by optical coherence tomography(OCT and OCTA)before and 1mo after the third injection. Mf-ERG was used to analyze the amplitude density of P1 wave and latency of P1, N1 wave from ring 1 and ring 2.

RESULTS: After treatment, BCVA(LogMAR)was improved significantly compared with that before(0.323±0.086 vs 0.773±0.304, P<0.05). CMT was lower than before(239.385±33.175μm vs 489.346±137.453μm, P<0.05), but there was no significant change in FAZ, VPD and VLD of SCP within 6mm×6mm of macular area before and after treatment(P>0.05). The latency of P1, N1 wave of ring 1 and ring 2 were significantly decresed from baseline, while the amplitude density of P1 wave was increased(P<0.05). Pearson correlation analysis shows that age, baseline BCVA, VLD, VPD, FAZ were significantly correlated with changes in visual acuity before and after treatment(P<0.05).

CONCLUSION: In patients with BRVO-ME, ranibizumab therapy can reduce CMT, improve BCVA and improve the structure and function of macular area. Age, BCVA before treatment and microstructure parameters of macular area can be used as predictors of vision improvement.