THE IMAGE WARPING TEST: A Novel Method to Quantify and Qualify Metamorphopsia.

Abstract

To determine the validity, accuracy, and acceptability of the image warping test (IWT), a novel test for the measurement of visual distortion in the central visual field. Twenty-five volunteers with metamorphopsia secondary to vitreoretinal pathologic condition were recruited at a tertiary referral center. All subjects underwent ophthalmologic examination and measurement of metamorphopsia using Amsler grid, Morphision, M-CHARTS, and the IWT. Construct validity was determined through assessment of the association between symptoms, pathologic condition, visual acuity, established metamorphopsia test results, and IWT results. There was close association between subjective estimation of metamorphopsia severity and IWT score ( P = 0.005), between Morphision result and IWT score ( P = 0.015), and between the nature of vitreoretinal pathologic condition and IWT score ( P = 0.007). There was no statistically significant correlation between best-corrected distance visual acuity and IWT score, and between M-CHARTS score and IWT score. The IWT allows the creation of a digital map of subjective metamorphopsia that effectively measures its severity and nature, and opens the possibility to its noninvasive correction in the future through inverse mapping of the distortion map onto live images.