Changes in retinal thickness are correlated with alterations of electroretinogram in eyes with central retinal artery occlusion

Background We investigated the relationship between the retinal thickness and electroretinogram (ERG) components in patients with central retinal artery occlusion (CRAO). Methods The optical coherence tomographic (OCT) images and ERGs of the nine patients (six men and three women; mean age, 61.8 years) were retrospectively analyzed. The thickness of the inner and outer retinal layers at 1 and 2 mm nasal and temporal to the fovea was measured in the horizontally scanned OCT images. The ratio of the inner layer thickness/sensory retinal thickness (IT/ST ratio) was calculated. The amplitudes of the a- and b-waves of the mixed rod-cone ERGs and the photopic negative response (PhNR) of the photopic ERGs were analyzed. The ratio of the amplitude of each component in the affected eye to that of the healthy fellow eye (a/f ratio) was calculated. Results In the chronic phase (1 to 8 months after onset, eight eyes), the inner layer was significantly thinner than that in the acute phase (P=0.0147, 0.0076, 0.002, and 0.0003 for 2 mm nasal, 1 mm nasal, 1 mm temporal, and 2 mm temporal respectively, within 5 days of onset, six eyes), while the thickness of outer layer was not significantly changed. The ERGs were recorded 6.4 +/- 1.5 days after the onset of CRAO. The median of the a/f ratio was 0.84 in the a-wave, 0.56 in the b-wave, and 0.27 in the PhNR. The IT/ST in the chronic phase was positively correlated with the a/f ratio of the amplitude of the PhNR. Conclusions Measurement of retinal thickness by OCT can be useful for monitoring the changes following CRAO. The correlation between the retinal thickness, especially inner layer thickness, and the ERG components was determined, suggesting that the PhNR in the acute phase might be a good indicator for predicting the thinning of the damaged retina in the chronic phase.