Decreased inner retinal activity in branch retinal vein occlusion

The electroretinogram, electro-oculogram and electroretinogram oscillatory potential all reflect the mass activity of the retina. The electroretinogram usually remains normal after branch retinal vein occlusion, whereas the electro-oculogram and oscillatory potential often show abnormalities. These tests thus have a differential sensitivity to branch retinal vein occlusion. However, whether the inner layer of the retina is affected in branch retinal vein occlusion has not been determined. In this study, conventional electroretinographic and oscillatory potential data were compared in 34 patients with branch retinal vein occlusion, while electroretinographic and electro-oculographic data were compared in 30 patients with branch retinal vein occlusion, in an attempt to determine whether the inner retina was affected in this disorder. None of the conventional electroretinographic variables showed any significant difference between the eyes with branch retinal vein occlusion and the fellow eyes. In the oscillatory potential test, however, the sum of the amplitudes of O1, O2, O3 and O4 showed a significant difference (p < 0.02). In addition, the light peak-dark trough ratio and the light peak showed a significant difference in the electro-oculogram (p < 0.05 and p < 0.05, respectively). Since the oscillatory potential and the electro-oculogram light rise potential reflect the activity of the inner retina, our data suggest that the inner retina was affected by branch retinal vein occlusion and that these variables are more sensitive indicators than the electroretinogram.