Photopic negative response in branch retinal vein occlusion with macular edema

In patients with branch retinal vein occlusion (BRVO) and macular edema, the relations among full-field electroretinogram (ffERG) parameters and parameters of retinal function or morphology remain uncertain. The objective of this study was to investigate the correlations between parameters of the ffERG, including the photopic negative response (PhNR), and retinal functional or morphological parameters in these patients. In 62 consecutive BRVO patients (mean age: 68.5 ± 10.6 years; 32 women and 30 men), the amplitude and implicit time of the a-wave cone, b-wave cone, 30 Hz flicker, and PhNR were calculated from the ffERG. Microperimetry was employed to measure the macular sensitivity within the central 4°, 10°, and 20° fields, while macular thickness and volume within these fields were measured by optical coherence tomography. Best-corrected visual acuity (BCVA) was determined on the logarithm of the minimum angle of resolution scale. The cone b-wave, 30 Hz flicker, and PhNR amplitudes showed a significant correlation with BCVA. In addition, the cone a-wave, cone b-wave, 30 Hz flicker, and PhNR amplitudes all showed a significant correlation with macular sensitivity within the central 4°, 10°, and 20° fields. Only the 30 Hz flicker amplitude showed a significant correlation with the macular thickness and volume within the 4°, 10°, and 20° fields, while the other ERG parameters did not. These findings suggest that PhNR may be a useful ERG parameter for evaluating inner retinal function in BRVO patients.