Relationship between metamorphopsia and inner retinal microstructure following intravitreal ranibizumab injection for branch retinal vein occlusion

To evaluate the effects of intravitreal ranibizumab injection (IVR) on metamorphopsia in patients with branch retinal vein occlusion (BRVO), and to assess the relationship between metamorphopsia and inner retinal microstructure and other factors. Thirty-three treatment-naïve eyes of 33 patients with macular edema caused by BRVO with at least 12 months of follow-up were included. The degree of metamorphopsia was quantified using the M-CHARTS. Retinal microstructure was assessed with spectral-domain optical coherence tomography. Disorganization of the retinal inner layers (DRIL) at the first month after resolution of the macular edema (early DRIL) and at 12 months after treatment (after DRIL) was studied. Central retinal thickness (CRT), and status of the external limiting membrane as well as ellipsoid zone were also evaluated. IVR treatment significantly improved best-corrected visual acuity (BCVA) and CRT, but the mean metamorphopsia score did not improve even after 12 months. Post-treatment metamorphopsia scores showed a significant correlation with pre-treatment metamorphopsia scores (P < 0.005), the extent of early DRIL (P < 0.05) and after DRIL (P < 0.05), and the number of injections (P < 0.05). Multivariate analysis revealed that the post-treatment mean metamorphopsia score was significantly correlated with the pre-treatment mean metamorphopsia score (P < 0.05). IVR treatment significantly improved BCVA and CRT, but not metamorphopsia. Post-treatment metamorphopsia scores were significantly associated with pre-treatment metamorphopsia scores, the extent of DRIL, and the number of injections. Prognostic factor of metamorphopsia was the degree of pre-treatment metamorphopsia.