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Emily Wiecek, Kameran Lashkari, Steven Dakin, Peter Bex; Qualitative and Quantitative Assessment of Metamorphopsia in Retinopathy Patients. Invest. Ophthalmol. Vis. Sci. 2013;54(15):2185.
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© ARVO (1962-2015); The Authors (2016-present)
Metamorphopsia (perceived distortion of visual space) is commonly experienced by patients with retinal pathology. Although this distortion is typically measured with Amsler charts, more objective and quantitative assessments are desirable for effective monitoring of the presence, progression, and remediation of visual impairment. We compare qualitative assessments with novel quantitative methods across a range of retinal pathologies.
An eleven-item questionnaire assessed metamorphopsia symptoms in 80 patients with monocular distortion from maculopathy. All patients completed an Amsler assessment (presented on a computer screen with fixation compliance monitored by an eye tracker), and 35 patients additionally completed two novel objective measures of metamorphopsia in the central five degrees of visual field. One task required participants to arrange dots in a square (combining spatial bisection and Vernier hyperacuities), and the other used spatial alignment of dichoptically-presented targets. A dichoptic task was also used as a binary measure of inter-ocular suppression.
Monocular distortions were suppressed by undistorted vision in the better eye in 45% of patients. Questionnaire scores from non-suppressing patients positively correlated with distortion measures; however there was no relationship between subjective and quantitative assessments for patients who experienced suppression (p =.03). There was significant negative correlation in the overall vertical direction of distortion between the two novel quantitative distortion assessments (p = .05), as well as a positive correlation between the directional displacement measured in the dichoptic task and the gaze-contingent Amsler grid quantification (p = .01). There were no significant correlations between localized measures of visual distortion across all three measures.
The onset and progression of visual impairment may be underreported in maculopathy due to the suppression of distorted visual input from the more impaired eye. It is critical to assess metamorphopsia monocularly, and we have introduced novel metrics to quantify such visual distortion in central vision.
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