Macular vessel reduction as predictor for recurrence of macular oedema requiring repeat intravitreal ranibizumab injection in eyes with branch retinal vein occlusion

Aim To determine whether there are factors that can predict the frequency of recurrences of macular oedema associated with branch retinal vein occlusion (BRVO). Methods We reviewed the medical records of 31 eyes with treatment-naive macular oedema associated with BRVO. All eyes received an intravitreal ranibizumab (IVR) injection and were followed with a pro re nata protocol for at least 12 months. A reinjection of ranibizmab was performed when the central foveal thickness was >= 300 mu m. At 1 month after IVR injection, the macular vessel reduction was calculated by comparing the vessel density in the optical coherence tomography angiography in the BRVO involved half to that in the non-involved half. Results The mean visual acuity improved from 0.35 +/- 0.27 logarithm of the minimal angle of resolution (logMAR) units (20/45; Snellen) at initial visit to 0.06 +/- 0.15 logMAR units (20/23) at 12 months (p<0.0001). During 12 months, the mean number of IVR injections was 3.8 +/- 1.8. Multivariate regression analysis showed that a greater macular vessel reduction at 1 month after initial IVR injection was significantly a negative predictor of frequency of IVR injections (beta=-0.5065, p=0.0082). The visual acuity and the central foveal thickness at the initial visit or at 1 month after initial IVR injection were not predictive factors for frequency of IVR injections. Conclusions Patients with BRVO with a large macular vessel reduction at 1 month after an initial IVR injection have fewer recurrences and thus lower frequency of IVR injections during 12 months.