A new method for quantification of metamorphopsia in patients with epiretinal membrane.

Purpose: We have developed a new method for quantification of metamorphopsia and applied it to study distorted vision resulting from epiretinal membrane (ERM).Patients and Methods: We prepared a modified Amsler chart, which was a square grid formed by black lines on a white background with 12 cm on a side and divided into 2-cm quadrants. The patients were asked to trace any straight lines on the chart which appeared irregular or curved. The length of all lines traced by the patients was measured except for the outer frame. The total length of the chart itself was 1.200 mm, but it would appear longer in patients with metamorphopsia. In addition, the severity of metamorphopsia was scored subjectively as follows: 1, absent; 2, slight; 3, mild; 4, moderate; and 5, severe. The relationship of the length to the score and to the visual acuity were analysed. Sixty-three patients with unilateral ERM were examined.Results: The length of the line ranged from 1,200 to 1,259 mm (mean 1,223.3 mm) and was correlated significantly to the score. Conclusions: This method might be applied usefully in evaluating the severity of metamorphopsia and the surgical outcome of eyes with ERM.