Visual acuity reporting in clinical research publications

Brittany C. Tsou, Neil M. Bressler

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


IMPORTANCE: Visual acuity results in publications typically are reported in Snellen or non-Snellen formats or both. A study in 2011 suggested that many ophthalmologists do not understand non-Snellen formats, such as logarithm of the Minimum Angle of Resolution (logMAR) or Early Treatment Diabetic Retinopathy Study (ETDRS) letter scores. As a result, some journals, since at least 2013, have instructed authors to provide approximate Snellen equivalents next to non-Snellen visual acuity values. OBJECTIVE: To evaluate how authors currently report visual acuity and whether they provide Snellen equivalents when their reports include non-Snellen formats. DESIGN: From November 21, 2016, through December 14, 2016, one reviewer evaluated visual acuity reporting among all articles published in 4 ophthalmology clinical journals from November 2015 through October 2016, including 3 of 4 journals that instructed authors to provide Snellen equivalents for visual acuity reported in non-Snellen formats. MAIN OUTCOMES AND MEASURES: Frequency of formats of visual acuity reporting and frequency of providing Snellen equivalents when non-Snellen formats are given. RESULTS: The 4 journals reviewed had the second, fourth, fifth, and ninth highest impact factors for ophthalmology journals in 2015. Of 1881 articles reviewed, 807 (42.9%) provided a visual acuity measurement. Of these, 396 (49.1%) used only a Snellen format; 411 (50.9%) used a non-Snellen format. Among those using a non-Snellen format, 145 (35.3%) provided a Snellen equivalent while 266 (64.7%) provided only a non-Snellen format. CONCLUSIONS AND RELEVANCE: More than half of all articles in 4 ophthalmology clinical journals fail to provide a Snellen equivalent when visual acuity is not in a Snellen format. Since many US ophthalmologists may not comprehend non-Snellen formats easily, these data suggest that editors and publishing staff should encourage authors to provide Snellen equivalents whenever visual acuity data are reported in a non-Snellen format to improve ease of understanding visual acuity measurements.

Original languageEnglish (US)
Pages (from-to)651-653
Number of pages3
JournalJAMA ophthalmology
Issue number6
StatePublished - Jun 2017

ASJC Scopus subject areas

  • Ophthalmology


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