Abstract
Purpose: :
A branch retinal vein occlusion (BRVO) leads to macular edema which is predominantly located in the superior or inferior side of the macula according to the location of the BRVO. The aim of this study was to evaluate the functional asymmetry between upper and lower macular regions in eyes with a BRVO using the focal macular electroretinograms (FMERGs) elicited by hemicircular stimuli.
Methods: :
FMERGs were elicited by hemicircular stimuli (15° in diameter) that stimulated the upper or the lower macula of 14 patients with macular edema secondary to BRVO. The amplitudes and implicit times of the FMERGs from opposite macular regions were compared.
Results: :
The mean amplitude of the a-wave was 0.59±0.31 μV from the affected side and 0.60±0.31 μV from the unaffected side. The mean implicit time of the a-wave was 31.9±3.7 msec from the affected side and 31.8±3.3 msec from the unaffected side. The mean amplitude of the b-wave was 1.51±0.54 μV on the affected side and 1.61±0.52 μV on the unaffected side. The mean implicit time of b-wave was 59.1±6.5 msec on the affected side and 58.9±5.7 msec on the unaffected side. The amplitudes and implicit times of a-wave and b-wave did not differ significantly between the macular region of affected side and unaffected side of BRVO (P>0.05, Wilcoxon signed-rank test).
Conclusions: :
A functional asymmetry between upper and lower macular regions was not detected in eyes with BRVO even though macular edema was predominantly located in the affected side of the macula by OCT. Macular function of unaffected side may be impaired as much as that of affected side of BRVO.
Keywords: vascular occlusion/vascular occlusive disease • electroretinography: clinical • macula/fovea