Correlations Between M-CHARTS and PHP Findings and Subjective Perception of Metamorphopsia in Patients with Macular Diseases

Purpose: To assess the correlations between a patient's subjective perception of metamorphopsia and the clinical measurements of metamorphopsia by M-CHARTS and PreView PHP (PHP).

Methods: The authors designed a 10-item questionnaire focusing on the symptoms of metamorphopsia and verified its validity with a Rasch analysis. M-CHARTS measured the minimum visual angle of a dotted line needed to detect metamorphopsia, and PHP used the hyperacuity function for detection. Subjects were 39 patients with idiopathic epiretinal membrane (ERM), 22 patients with idiopathic macular hole (M-hole), 19 patients with age-related macular degeneration (AMD), and 51 healthy controls.

Results: Rasch analysis suggested the elimination of one question. The nine-item questionnaire score significantly correlated to the M-CHARTS score in ERM (r = 0.59; P = 0.0004) but not in M-hole and to the PHP result in AMD (r = -0.29; P = 0.04) but not in ERM. Eighty percent of ERM patients with greater horizontal M-CHARTS score subjectively perceived horizontal metamorphopsia more often. M-CHARTS showed better sensitivities than PHP in both ERM (89% vs. 42%) and AMD (74% vs. 68%) and better specificity (100% vs. 71%) in healthy controls. Rasch analysis indicated that the present form of the questionnaire is better suited for moderate to severe cases of metamorphopsia than for mild cases.

Conclusions: The questionnaire appears to be a valid assessment of patient subjective perception of metamorphopsia and can be used to supplement the clinical measurements of metamorphopsia by M-CHARTS and PHP in patients with macular diseases.