Focal macular electroretinogram in macular edema secondary to central retinal vein occlusion

To evaluate the usefulness of focal macular electroretinography (fmERG) for evaluation of macular function in eyes with central retinal vein occlusion (CRVO).

fmERG recordings were made prospectively in 24 patients with unilateral CRVO. The amplitudes and latencies of the a-wave, b-wave, and photopic negative response (PhNR) were compared with other biological parameters, including visual acuity (VA), retinal sensitivity measured with a microperimeter, and optical coherence tomography.

In eyes affected by CRVO, amplitudes of the a-wave, b-wave, and PhNR were reduced significantly, and latencies were prolonged significantly compared with those of healthy fellow eyes (P < 0.001). Relative amplitudes (affected eye/fellow eye) of each wave showed a cross correlation with VA. Furthermore, both relative amplitudes and latencies of each wave tended to correlate with retinal sensitivity within the macular area. Central foveal thickness showed a correlation with both relative amplitude and relative latency. Among all parameters, relative amplitude of the PhNR correlated most strongly with central foveal thickness (r = -0.598, P = 0.0042). In addition, sensory retinal thickness showed a correlation with relative latencies, and height of the retinal detachment (when present) showed a correlation with relative amplitudes. In ischemic CRVO, relative amplitudes were reduced more severely than were those in nonischemic CRVO.

In eyes with CRVO, amplitudes and latencies of the fmERG correlated with other biological parameters. Based on the present study, fmERG appears to be useful for the examination of the macular edema that accompanies CRVO.