Function and morphology of macula before and after removal of idiopathic epiretinal membrane.
OBJECTIVE
To study the function and morphology of the macula of the eye before and after the removal of unilateral idiopathic epiretinal membrane (ERM).


METHODS
Focal macular electroretinograms (fmERGs) elicited by a 15 degrees stimulus were recorded in 37 eyes of 37 patients with a unilateral ERM. The amplitudes of the a- and b-waves and the oscillatory potentials (OPs) were compared with the corresponding waves in the normal fellow eyes before and after removal of the ERM. In 29 eyes followed up for more than 6 months after surgery, the fmERGs and foveal and parafoveal thicknesses, measured by optical coherence tomography (OCT), were evaluated.


RESULTS
Before surgery, the mean amplitudes of all components of the fmERGs were significantly smaller than in the fellow eyes, with the decrease largest for the OPs, followed by the b-waves and then the a-waves. The eyes with less severely reduced a-wave amplitude (>70% of the fellow eyes) had significantly lower b-wave to a-wave (b/a) ratios. After surgery, the amplitudes of the b-wave and OPs were still significantly smaller in the affected eyes. The mean foveal and parafoveal thicknesses were significantly less after surgery; however, the thickness was still more in the affected eyes. The decrease of the OPs remained after surgery and correlated with increased parafoveal thickness (r = -0.460, P = 0.011).


CONCLUSIONS
The decreased fmERGs indicate that macular function is impaired in eyes with ERM. The decrease of the b-wave and OPs in the 29 eyes examined after vitrectomy may be due to the still thickened macular retina.
Niwa
Takashi
T
Department of Ophthalmology, Nagoya University School of Medicine, Nagoya, Japan.
Terasaki
Hiroko
H
Kondo
Mineo
M
Piao
Chang-Hua
CH
Suzuki
Toshimitsu
T
Miyake
Yozo
Y
D000368:Aged; D004596:Electroretinography; D019773:Epiretinal Membrane / Q000503:physiopathology* / Q000601:surgery; D005260:Female; D006801:Humans; D007368:Interferometry; D008027:Light; D008266:Macula Lutea / Q000473:pathology* / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D014054:Tomography; D014792:Visual Acuity; D014821:Vitrectomy