Morphision: A method for subjective evaluation of metamorphopsia in patients with unilateral macular pathology (i.e., full thickness macular hole and epiretinal membrane)

BACKGROUND: Lack of clinical tests to quantify spatial components of distortion in patients with full thickness macular holes (FTMH) and epiretinal membranes (ERM). AIM: To develop a test for subjective evaluation of visual distortion in the central visual field around fixation in patients with unilateral FTMH or ERM. SETTINGS AND DESIGN: Prospective case-control study carried out at tertiary referral center. MATERIALS AND METHODS: Twenty-five patients with unilateral macular disease (13 macular epiretinal membranes, 12 full-thickness macular holes), and nine controls (without ocular pathology) underwent ophthalmological examination with logMAR ETDRS visual acuity, near vision and contrast sensitivity assessed. Macular optical coherence tomography and metamorphopsia assessment using Morphision test was also carried out. This test consists of a set of modified Amsler charts for detection, identification, and subjective quantification of visual distortion in the central visual field around fixation. Morphision test content and construct validity, and reliability (test-retest method) were evaluated. Sixteen patients completed an unstructured survey on test performance and preference. RESULTS: Every patient with unilateral FTMH or ERM identified a particular chart using Morphision test (content validity). None of the normal subjects without symptoms of metamorphopsia identified any distortion (construct validity). Test-retest showed a 100% consistency for frequency and 67% for amplitude. The mean amplitude difference between measurements was 0.02 degrees (SD = 0.038). The coefficient of repeatability was 0.075. There was a correlation between Morphision amplitude score and visual acuity and contrast sensitivity, individually. CONCLUSIONS: Morphision test allowed detection and subjective quantification of metamorphopsia in the clinical setting in our patients with unilateral macular epiretinal membranes and full thickness macular holes.