Correlations among Metamorphopsia Test Scores,Optical Coherence Tomography Findings and Multifocal Electroretinogram Responses in Epiretinal Membrane Patients

Abstract

Purpose: To quantify metamorphopsia with a novel metamorphopsia test method in patients with epiretinal membrane (ERM) and to investigate the relationships among metamorphopsia scores, spectral-domain optical coherence tomography (OCT) findings and multifocal electroretinogram (mfERG) responses. Subjects and Methods: This is a cross-sectional observational study, and the study included 52 eyes of 52 patients with idiopathic ERM who underwent comprehensive ophthalmologic examinations, including measurement of best-corrected visual acuity (BCVA), fundus examination, OCT scan, and mfERG recording. The degree of metamorphopsia was quantified using the MonPack One® (Metrovision, Perenchies, France). On the topographic map of the Early Treatment Diabetic Retinopathy (ETDRS) grid using OCT scans, the averaged retinal thickness in the central, superior, inferior, nasal, temporal subfields were measured, and the mean metamorphopsia scores for each corresponding subfield were also obtained. The amplitudes and implicit times of mERG were elicited from each subfield. Then, the correlations among metamorphopsia scores, OCT findings, and mfERG responses were analyzed. Results: The mean age of the patients was 65.3 ± 18.5 years, and the average metamorphopsia score of the individual subfields was 2.03 ± 1.18. The mean BCVA was 0.50 ± 0.12 LogMAR, and there was a significant correlation between metamorphopsia scores at central (foveal) subfield and BCVA. The metamorphopsia scores from the central subfields showed significant correlations with central retinal thickness (CRT) (p=0.001). The mean metamorphopsia scores in the central subfield showed a significant relationship with the mean N1 and P1 amplitudes (p=0.001, p=0.048, respectively), while no relationship was observed between metamorphopsia scores and mfERG amplitudes in other subfields. Conclusions: The degree of metamorphopsia in ERM patients could be quantified by a novel metamorphopsia test, and the mean metamorphopsia scores were obtained in each subfield. The metamorphopsia scores were significantly correlated with retinal thickness, especially at the central subfields, and the scores in the central subfields were also significantly correlated with the N1 and P1 amplitudes of mfERG. Thus, the metamorphopsia test can be a useful method to evaluate metamorphopsia symptoms for ERM patients.