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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.