Prognostic factors for visual outcome after idiopathic epiretinal membrane surgery

Abstract

[한글]

[영문]This study is to evaluate the role of preoperative optical coherence tomography (OCT) and multifocal electroretinogram (mERG) and their predictive values for visual outcome after idiopathic epiretinal membrane (ERM) removal surgery.The clinical records of 87 patients (87 eyes) with unilateral ERM who underwent vitrectomy from January 2005 to May 2008 were reviewed. The mfERG responses and central macular thickness (CMT) measured by OCT were evaluated before the surgery. Patients were categorized into the two groups. Group 1 consisted of the patients with 2 or more lines of visual recovery on Early Treatment Diabetic Retinopathy Study (ETDRS) chart, and the rest of them were placed in group 2. Comparative clinical, OCT, and mfERG characteristics were analyzed.The mean ETDRS score improved from 33.6±14.3 to 43.9±13.4 at six months after surgery (P < 0.05, paired t-test). Fifty-nine eyes were classified into group 1. Preoperative CMT showed a negative correlation with postoperative ETDRS score (r= -0.536, p<0.05, Pearson correlation). While P1 implicit time delay at an eccentricity of 0-5° was associated with postoperative ETDRS score (r= -0.318, p=0.017, Pearson correlation), relative amplitude was not correlated with visual outcome. In the logistic regression model, the duration of symptoms and CMT had the significant correlations with favorable visual recovery among other variables. (p=0.031, 0.038).In conclusion, the CMT had the prognostic value, while mfERG responses were limited to predict favorable visual outcome. The duration of symptoms was also found to be an important factor suggesting that early membrane removal is required to achieve better results.