Quantification of metamorphopsia in patients with epiretinal membranes.

PURPOSE To quantify the degree of metamorphopsia in patients with idiopathic epiretinal membranes (ERMs), by use of a new metamorphopsia chart (M-CHARTS) developed by the authors. METHODS These M-CHARTS had 19 dotted lines with dot intervals of between 0.2 degrees (fine) and 2.0 degrees (coarse) visual angles. As the dot intervals were changed from fine to coarse, a decrease in the severity of metamorphopsia was noted. In this study, the minimum visual angle of the dotted lines needed to cause the metamorphopsia to disappear was measured in 51 eyes of 51 patients with ERM. The metamorphopsia scores were compared with the stages of ERM classified by scanning laser ophthalmoscope (SLO) images. RESULTS In patients with ERM, the metamorphopsia score increased depending on the severity of membrane proliferation classified by SLO images. The scores obtained from the horizontal dotted lines were larger than those of the vertical lines in advanced stages of ERM. CONCLUSIONS M-CHARTS provide a very simple and useful method for evaluating the severity of metamorphopsia in patients with ERM.