Validation of the M-CHARTS tool as an objective measure of vertical and horizontal metamorphopsia following rhegmatogenous retinal detachment repair

Abstract

Purpose : Many patients are dissatisfied following rhegmatogenous retinal detachment (RRD) repair often related to post-operative metamorphopsia. Although M-CHARTS testing has been validated for other retinal pathologies, it has yet to be validated in patients following RRD repair. The purpose of this study is to validate the M-CHARTS as an objective measure of post-operative metamorphopsia.

Methods : This is a REB approved prospective observational, single-center study performed at St. Michael’s Hospital in Toronto, Canada. Subjects presenting following RRD repair with pars plana vitrectomy (PPV) or pneumatic retinopexy (PnR) were included. Patients presenting to the clinic without macular pathology were recruited as controls. Subjective metamorphopsia was assessed using a metamorphopsia questionnaire and objective M-CHARTS testing was performed at 3 months postoperatively in all patients. The correlation between the subjective metamorphopsia questionnaire score and the objective MCHARTS score was determined.

Results : Fifty subjects with RRD and 50 controls were enrolled. 76% (n = 38) of subjects with RRD had metamorphopsia to some degree on M-CHARTS testing and 82% (n = 41) had metamorphopsia on the questionnaire at 3 months. Metamorphopsia questionnaire socre, horizontal, vertical, and total MCHARTS scores were significantly higher in subjects with RRD compared to controls (all p< 0.0001). Cronbach’s alpha reliability coefficient for the metamorphopsia questionnaire in subjects with RRD measured 0.956. The questionnaire scores were significantly correlated to the horizontal, vertical, and total MCHARTS scores (rs = 0.400, P = 0.004; rs= 0.399, P = 0.004; rs= 0.459; P = 0.001, respectively). Total MCHARTS score showed a sensitivity of 85.4% and a specificity of 66.7% with an area under the ROC curve of 0.801. A significant interaction was found when comparing subjects who had an MCHARTS score greater than 0.1 and had subjective metamorphopsia (x² (1) = 10.954, P = 0.001).

Conclusions : Metamorphopsia is a frequent occurrence following RRD repair. MCHARTS testing appears to be a valid objective tool to quantitatively measure metamorphopsia in subjects following RRD with a strong correlation with the metamorphopsia questionnaire. MCHARTS testing should be included as an outcome measure in clinical trials related to retinal detachment repair.

This is a 2020 ARVO Annual Meeting abstract.