METAMORPHOPSIA AND TANGENTIAL RETINAL DISPLACEMENT AFTER EPIRETINAL MEMBRANE SURGERY

To determine whether the degree of metamorphopsia significantly correlated with the distance of the tangenital retinal displacement after epiretinal membrane surgery. The M-CHARTS were used to measure the vertical metamorphopsia score and the horizontal score. The distances between the intersections of two sets of retinal vessels situated vertically or horizontally were measured in the near-infrared Spectralis images. Fifty eyes of 50 patients (22 men; age, 69.5 ± 7.8 years) were retrospectively studied. The vertical and horizontal metamorphopsia scores significantly improved at 1 month after the surgery, and the vertical and horizontal retinal distances increased. The baseline horizontal and vertical metamorphopsia scores significantly correlated with the ratio of the pre- and postoperative vertical and horizontal retinal displacements, respectively (P = 0.038 and P = 0.015 at 1 week; P = 0.036 and P = 0.036 at 1 month). The postoperative horizontal metamorphopsia score at 1 month and the vertical metamorphopsia score at 3 months significantly correlated with the vertical displacement at 1 month (P = 0.034) and the horizontal displacement at 3 months (P = 0.001), respectively. The degree of metamorphopsia significantly correlated with the tangential retinal displacement. Dislocated Muller cells may stimulate the photoreceptors located away from original positions, which consequently results in the sensation of metamorphopsia in patients with an epiretinal membrane.