Assessment of macular function by multifocal electroretinography following epiretinal membrane surgery with internal limiting membrane peeling

Abstract

The aim of the current study was to evaluate macular function before and after surgery for idiopathic epiretinal membranes with internal limiting membrane (ILM) peeling by means of multifocal electroretinography (ERG). Eighteen eyes of 18 patients who underwent vitrectomy with ILM removal were included. Best corrected visual acuity, optical coherence tomography (OCT), and multifocal electroretinography were assessed prior to surgery, and 3 and 12 months after surgery. All surgical samples were obtained and confirmed inclusion of an ILM by electron microscopy. Visual acuity and the central foveal thickness by OCT improved significantly 3 months postoperatively, with gradual recovery by 12 months. Preoperatively, only the P1 amplitude in rings 1 and 2 were decreased compared with the normal fellow eyes (P < 0.01). Three and 12 months after surgery, the P1 amplitude in rings 1 and 2 were decreased compared with the preoperative P1 amplitudes, but without significance. The photoreceptor status by OCT was related to the N1 amplitude before and after surgery. Although visual acuity and macular edema were improved after surgery, macular function, as indicated by multifocal ERG, had limited recovery at 12 months.

Keywords: epiretinal membrane; macular function; multifocal electroretinography.

Figure 1

Transmission electron micrographs of internal limiting membranes removed from eyes with idiopathic macular epiretinal membrane. Specimen shows fragments of retinal debris (arrow) at the retinal side of the internal limiting membrane (asterisk) (original magnification × 4400; bar = 1.7 μm).

Figure 2

Optical coherence tomographic (OCT) image of macula (upper) and the first order trace array of multifocal electroretinography (lower). A 66-year-old woman with idiopathic epiretinal membrane presented best-corrected visual acuity (BCVA) of 20/50 before surgery. OCT showed disruption of the line representing between inner segment/outer segment junction (Left). Three months after surgery, her visual acuity was improved to 20/40, and OCT showed decreased macular edema and disrupted photoreceptor line (Middle). Twelve months after surgery, her BCVA was 20/40, and OCT showed foveal contour recovery and intact photoreceptor line. Serial changes in multifocal electroretinography responses showed gradual decreased P1 amplitude following ERM surgery.