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Mariana S. Lopes, Shiri Zayit-Soudry, Ala Moshiri, Susan B. Bressler, Neil M. Bressler; Understanding and Reporting Visual Acuity Measurements in Publications of Clinical Research in Retina. Invest. Ophthalmol. Vis. Sci. 2011;52(14):1893. doi: https://doi.org/.
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To investigate methods used to report visual acuity in published retina literature, and evaluate understanding of those methods.
All retina papers published in 2008 among four leading clinical journals were reviewed. The full text of each paper was examined by at least two authors, and each method of visual acuity reporting used was recorded. Five residents, four ophthalmologists in retina training, and five retina faculty were surveyed to evaluate their ability to interpret various visual acuity methods.
Among 356 retina papers, 206 reported visual acuity, including 175 (85%) of the 206 which reported Snellen acuities. Other methods included a letter score based on the log of the minimal angle of resolution (logMAR) in 106 papers (51.5%), a letter score derived from the number of letters read on an Early Treatment Diabetic Retinopathy Study (ETDRS) chart in 67 papers (32.5%), decimal notation in 13 papers (6.3%), and fractions other than Snellen equivalent in 1 paper (0.5%). Among the 140 papers using notations other than Snellen, 31 (22.1%) did not provide a Snellen equivalent. The majority of physicians surveyed, regardless of level of training, were unable to translate an ETDRS letter score or logMAR value to an approximate Snellen equivalent correctly.
Many publications in major ophthalmic journals do not provide Snellen equivalent of letter scores derived from an ETDRS chart or logMAR values. Journals should consider requiring Snellen equivalents until data show a greater understanding or facility with letter scores or logMAR values.
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