OSLI Retina

November 2019

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734 Ophthalmic Surgery, Lasers & Imaging Retina | Healio.com/OSLIRetina ■ C A S E R E P O R T ■ Elimination of a False-Negative Result With the M-CHARTS Metamorphopsia Assessment Tool Achieved Through Sampling Oblique Axes Jacob A. Lifton, BA; Andrew A. Moshfeghi, MD, MBA ABSTRACT: Standard implementation of the M- CHARTS metamorphopsia tool presents patients with only vertical and horizontal lines, potentially overlooking distortions not occurring within those precise meridians. The authors propose rotating the M-CHARTS testing booklet about the central fixa- tion point until maximal distortion is perceived, after which sequential M-CHARTS testing can take place along that same axis. In a symptomatic pa- tient with residual parafoveal fluid cysts after re- lease of vitreomacular traction, M-CHARTS testing yielded standard testing scores of 0 (false-negative); upon rotating the reference test line, a score of 0.3 was measured at the 30° meridian. The authors be- lieve this modification of the original methodology is more sensitive and more accurately reflects the severity of a patient's distortions. [Ophthalmic Surg Lasers Imaging Retina. 2019;50:734-736.] INTRODUCTION The accurate detection and quantification of meta- morphopsia allows the retinal physician to have a more complete understanding of the correlation between vi- sual symptomatology and disease severity, aiding in the identification of additional indications for surgical in- tervention. Besides subjective Amsler grid testing, there are currently several ways to detect and quantify meta- morphopsia; however, the most commonly used tool in prospective clinical trials is the M-CHARTS metamor- phopsia tool (Inami & Co., Ltd., Tokyo, Japan). 1-5 The M-CHARTS tool is an analog testing booklet which an examiner presents to a patient with subjective reports of visual distortion; the first page of the booklet displays a solid, objectively straight line bisecting a cen- tral fixation point. The patient is asked to focus on the central point, and if distortion is perceived at any point along the line, a second dotted line with decreased spa- tial frequency is presented in the same configuration. This process is repeated, with each new line comprising regularly spaced dots of decreasing spatial frequency, until the patient no longer perceives a distorted line. 1 The distance between each dot of the final line, mea- sured in degrees of visual angle, represents the patient's effective metamorphopsia score, or "M-score," along that axis. Standard use of the test — as described by the manufacturer — only involves performing these steps with vertical and horizontal lines; thus, visual distor- tions that lie outside the 90° and 180° axes may not be detected by the tool, and the test may yield inaccurate or incomplete information about the severity of a pa- tient's symptoms. Given the heterogeneity of macular anatomic derangement in complex vitreoretinal inter- face disorders such as epiretinal membrane and vitreo- macular traction syndrome, it is quite possible that only testing the vertical and horizontal meridians would re- sult in many false negative results. We present a novel use for the M-CHARTS tool in which the testing cards are rotated about the fixation point until the patient perceives the greatest amount of distortion. Sequential M-CHARTS testing can then take place along that axis, which will more accurately reflect the severity of any reported distortion. This method was attempted on a patient with vitreomacular traction with significant symptoms of metamorphopsia, and we be- lieve it was better able to detect and quantify her visual symptoms than standard M-CHARTS testing. This case report was exempt from institutional review board re- view but was carried out in line with the tenets of the Declaration of Helsinki. CASE REPORT The patient is a 60-year-old female with no known ocular comorbidities who was referred to our retina From Keck School of Medicine, University of Southern California, Los Ange- les (JAL); and USC Roski Eye Institute, Department of Ophthalmology, Keck School of Medicine, University of Southern California, Los Angeles (AAM). Originally submitted November 7, 2018. Revision received March 7, 2019. Accepted for publication April 22, 2019. Supported in part by an unrestricted grant to the Department of Ophthal- mology from Research to Prevent Blindness, New York, NY, and from the National Institutes of Health (Bethesda, MD) grant P30EY029220 (AAM). The authors report no relevant financial disclosures. Address correspondence to Andrew A. Moshfeghi, MD, MBA, USC Roski Eye Institute, 1450 San Pablo St., Los Angeles, CA 90033; email: Andrew. moshfeghi@med.usc.edu. doi: 10.3928/23258160-20191031-09

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