Changes in metamorphopsia in daily life after successful epiretinal membrane surgery and correlation with M-CHARTS score

Abstract

Purpose: To determine the correlation between the changes in metamorphopsia in daily life environment and the M-CHARTS scores after epiretinal membrane (ERM) removal, and to determine the criterion for determining whether clinically significant changes in the metamorphopsia score have occurred in M-CHARTS.

Methods: We studied 65 eyes undergoing vitrectomy for unilateral ERM. Self-administered questionnaires were used to examine the metamorphopsia in their daily life. The degree of metamorphopsia was determined by M-CHARTS. The receiver operating characteristic curve was used to determine the best predictor of the changes in metamorphopsia in daily life. To determine the reproducibility of the M-CHARTS score, another set of 56 eyes with ERM was tested twice on two different days.

Results: The postoperative changes in the logarithm of the M-CHARTS score was defined as M2-value. The area under the receiver operating characteristic curve for the M2-value as a predictor of the changes in metamorphopsia in daily life was larger than area under the receiver operating characteristic curve obtained for any other parameter. The optimal cutoff value was -0.4. The 95% limits of agreement between test and retest measurements had a reproducibility of ±0.3 logarithm of the M-CHARTS score. Taking into account not only the reproducibility but also the consistency with the subjective changes, we determined the criterion for clinically significant changes in the M-CHARTS scores as a change of the M2-value by ≥0.4.

Conclusion: Evaluating the changes in the M-CHARTS scores in logarithmic form is favorable not only theoretically but also from the perspective of consistency with the subjective changes.

Keywords: ERM; criterion; metamorphopsia score; vitrectomy.

Figures

Figure 1

Self-administered questionnaire used in the study. Notes: Questions 1 and 2 were asked at each visit, and Question 3 was asked only at 12 months after the surgery.

Figure 2

Method of determining the metamorphopsia score using M-CHARTS. Notes: The minimum angle of the dots that appeared straight was taken to be the metamorphopsia score. In this case, metamorphopsia for vertical lines (MV) is 0.4.

Figure 3

Changes in the percentage of patients without metamorphopsia and the mean metamorphopsia scores. Notes: The percentage of patients without metamorphopsia increased as the metamorphopsia scores decreased until finally 35.4% of patients had no metamorphopsia in their daily life at 12 months. Error bars indicate standard error. *,†Statistically significant compared with the metamorphopsia score at baseline (P<0.001), n=65. Abbreviations: MV, metamorphopsia for vertical lines; MH, metamorphopsia for horizontal lines.

Figure 4

ROC curve for six variables to predict the change in the metamorphopsia in daily life. Notes: The ROC curve with the largest AUC was obtained for the M2-value. M1 = either (MHpost-MHpre) or (MVpost-MVpre), whichever of these absolute values was larger was used. M2-value = either (logMHpost-logMHpre) or (logMVpost-logMVpre), whichever of these absolute value was larger was used. Abbreviations: ROC, receiver operating characteristic; AUC, area under the ROC curve; logMV, logarithm of MV score; logMH, logarithm of MH score; MV, metamorphopsia for vertical lines; MH, metamorphopsia for horizontal lines.