Influence of retinal ischemia on macular function after pars plana vitrectomy for macular edema with branch retinal vein occlusion

The influence of retinal ischemia on changes of visual acuity, macular sensitivity, macular thickness, and macular volume is unclear after pars plana vitrectomy (PPV) for macular edema with branch retinal vein occlusion (BRVO). Twenty-three patients (23 eyes) with BRVO and macular edema underwent PPV. Retinal ischemia was evaluated from capillary non-perfusion on fluorescein angiography, and patients were classified as ischemic or nonischemic. Microperimetry was performed with a Micro Perimeter 1. Macular thickness and volume were measured by optical coherence tomography. Mean macular thickness within the central 4°, 10°, and 20° fields decreased significantly from before to 3 and 6 months after PPV (all P < 0.001). Likewise, total macular volume within the central 4°, 10°, and 20° fields decreased significantly from before to 3 and 6 months after PPV (all P < 0.001). Best-corrected visual acuity (BCVA) improved significantly from before to 3 and 6 months after PPV (P < 0.001). Furthermore, mean macular sensitivity within the central 4°, 10°, and 20° fields increased significantly from before to 3 and 6 months after PPV (P = 0.002, P = 0.001, and P = 0.001, respectively). There were no significant differences in the trend profiles of macular thickness, macular volume, and BCVA between the ischemic and nonischemic groups. However, there was a significant difference in the trend profile of macular sensitivity within the central 4°, 10°, and 20° fields between the ischemic and nonischemic groups (P = 0.017, P = 0.010 and P = 0.025, respectively). These findings suggest PPV may be more effective for improving macular sensitivity in ischemic than nonischemic BRVO.