Retinal contraction and metamorphopsia scores in eyes with idiopathic epiretinal membrane

PURPOSE. Using M-CHARTS (Inami Co., Tokyo, Japan), which were developed by the authors to measure metamorphopsia, and image-analysis software, which was developed to quantify retinal contraction, the authors investigated the relationship between the degree of retinal contraction and the degree of metamorphopsia in eyes with idiopathic epiretinal membrane (ERM). METHODS. This study was conducted in 29 eyes with ERM ( 29 patients, 20 women; mean age, 62.1 +/- 8.6 years) observed for at least 3 years ( mean, 3.55 +/- 0.6 years) after diagnosis. Horizontal (MH) and vertical (MV) metamorphopsia scores were obtained with the M-CHARTS. Horizontal and vertical retinal contraction due to ERM was measured by using image-analysis software developed by the authors to calculate horizontal and vertical components of changes in the locations of retinal vessels on sequential fundus images. RESULTS. There was a significant ( P < 0.01) positive correlation between the degree of retinal contraction and metamorphopsia score. In addition, there were significant positive correlations between horizontal contraction of the retina and the MV score ( P < 0.01) and between vertical contraction of the retina and the MH score ( P < 0.05). No significant correlations were found between change in the metamorphopsia score and change in visual acuity or mean defect. CONCLUSIONS. Metamorphopsia scores correlate well with measurements of retinal contraction due to idiopathic ERM. Using M-CHARTS is a simple and useful method for quantitatively monitoring metamorphopsia in patients with ERM.