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Brittany Tsou, Neil Bressler; Visual acuity reporting in clinical research publications. Invest. Ophthalmol. Vis. Sci. 2017;58(8):5714.
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© ARVO (1962-2015); The Authors (2016-present)
Although visual acuity (VA) in publications can be reported in different ways, e.g., Snellen format (20/40) or non-Snellen formats (including logarithm of the Minimum Angle of Resolution [logMAR], e.g., 0.3, Early Treatment Diabetic Retinopathy Study [ETDRS] letter score, e.g., 70, decimal notation, e.g., 0.50, or metric fractional notation, e.g., 6/12), a study in 2011 suggested many ophthalmologists do not understand Snellen equivalents of logMAR or ETDRS letter scores. As a result, some journals since at least 2013 have instructed authors to provide approximate Snellen equivalents (20/20, 20/40 etc.) next to VA not in Snellen format. This study evaluates how authors currently report VA, and whether they provide Snellen equivalents for non-Snellen formats.
We reviewed VA reporting among all articles published in 3 ophthalmology clinical journals (JAMA Ophthalmology, Ophthalmology, and American Journal of Ophthalmology) from November 2015 through October 2016. We determined occurrence of various VA reporting formats and how frequently VA reports in non-Snellen format provided Snellen equivalents.
Of the 1425 articles reviewed, 555 (38.9%) provided a VA measurement. Of these, 281 (50.6%) used Snellen format; 274 (49.4%) used a non-Snellen format. Of the 274 articles reporting VA in a non-Snellen format, 167 (60.9%) used logMAR, 59 (21.5%) used ETDRS letter score, 28 (10.2%) used decimal notation, and 20 (7.3%) used metric fractional notation. Among those using a non-Snellen format, 76 (27.7%) provided a Snellen equivalent and 198 (72.3%) only used a non-Snellen format, including 109 (55.1%) providing VA only using logMAR and 45 (22.7%) providing VA only using ETDRS letter score.
Although prior studies suggested many ophthalmologists do not understand Snellen equivalents of logMAR or an ETDRS letter score, and some journals recently have instructed authors to provide a Snellen equivalent when VA is not in Snellen format, about half of all articles in 3 ophthalmology clinical journals still fail to do so. Since many U.S. ophthalmologists familiar with Snellen format may not comprehend non-Snellen formats easily, these data suggest that editors and publishing staff should encourage authors to provide Snellen equivalents whenever VA data are reported in a non-Snellen format to improve ease of understanding VA measurements.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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