Multifocal electroretinogram in retinal vein occlusion

To determine the effects of retinal vein occlusion (RVO) on multifocal electroretinogram (MF-ERG) parameters, to correlate MF-ERG and standard electroretinogram (ERG) and to correlate MF-ERG with findings of optical coherence tomography (OCT) in cases of RVO.

Both eyes of 50 patients with RVO and 50 eyes of 25 normal subjects were examined using MF-ERG, standard ERG, fluorescein angiography and OCT. The latency in millisecond (ms) and response density in nanovolt (nv/degenerations) were measured for each of four quadrant areas and central area. OCT was used to measure the foveal retinal thickness. Fluorescein angiography was used to measure retinal ischemia.

Central retinal vein occlusion (CRVO) markedly affected all parameters of MF-ERG. In pathological quadrants in branch retinal vein occlusion, the response densities of MF-ERG were decreased and latencies of p-wave were prolonged. The MF-ERG responses obtained from eyes with RVO were significantly different (P > 0.05) from derived from the fellow eyes. The amplitude of MF-ERG were abnormal in 40 eyes and implicit times were delayed in 48 eyes compared with normal subjects. While 30 Hz flicker implicit were abnormal in only 24 eyes with RVO. Implicit times were prolonged in eyes with macular ischemia than in eyes without ischemia. There were significant correlation between foveal retinal thickness measured by OCT and P response density MF-ERG in cases of retinal vein occlusion.

MF-ERG is more susceptible than standard ERG to eye changes of RVO due to the multiple frequencies of stimulation used to record MF-ERG response. MF-ERG could be sensitive indicator of underlying disease affecting the retinal in eyes with RVO. MF-ERG is useful for detecting local retinal dysfunction in patients with RVO and sensitive to morphological changes and functional disorders induced by RVO.