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Visual acuity measured with a smartphone app is more accurate than Snellen testing by emergency department providers

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Abstract

Purpose

To assess the accuracy of best-corrected visual acuity (BCVA) measured by non-ophthalmic emergency department (ED) staff with a standard Snellen chart versus an automated application (app) on a handheld smartphone (Paxos Checkup, San Francisco, CA, USA).

Methods

The study included 128 subjects who presented to the Stanford Hospital ED for whom the ED requested an ophthalmology consultation. We conducted the study in two phases. During phase 1 of the study, ED staff tested patient BCVA using a standard Snellen test at 20 feet. During phase 2 of the study, ED staff tested patient near BCVA using the app. During both phases, ophthalmologists measured BCVA with a Rosenbaum near chart, which was treated as the gold standard. ED BCVA measurements were benchmarked prospectively against ophthalmologists’ measurements and converted to logMAR.

Results

ED logMAR BCVA was 0.21 ± 0.35 (approximately 2 Snellen lines difference ± 3 Snellen lines) higher than that of ophthalmologists when ED staff used a Snellen chart (p = .0.00003). ED BCVA was 0.06 ± 0.40 (less than 1 Snellen line ± 4 Snellen lines) higher when ED staff used the app (p = 0.246). Inter-observer difference was therefore smaller by more than 1 line (0.15 logMAR) with the app (p = 0.046).

Conclusions

BCVA measured by non-ophthalmic ED staff with an app was more accurate than with a Snellen chart. Automated apps may provide a means to standardize and improve the efficiency of ED ophthalmologic care.

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Authors and Affiliations

  1. Stanford University School of Medicine, Stanford, CA, USA

    Akhilesh S. Pathipati

  2. Department of Ophthalmology, Byers Eye Institute, Stanford University School of Medicine, 2452 Watson Ct, Palo Alto, CA, USA

    Edward H. Wood, Carson K. Lam, Christopher S. Sáles & Darius M. Moshfeghi

  3. Ophthalmic Consultants of Boston, Boston, MA, USA

    Christopher S. Sáles

Authors
  1. Akhilesh S. Pathipati
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  2. Edward H. Wood
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  3. Carson K. Lam
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  4. Christopher S. Sáles
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  5. Darius M. Moshfeghi
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Corresponding author

Correspondence to Darius M. Moshfeghi.

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No funding was received for this research.

Conflict of interest

All authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest (such as honoraria; educational grants; participation in speakers’ bureaus; membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent-licensing arrangements), or non-financial interest (such as personal or professional relationships, affiliations, knowledge, or beliefs) in the subject matter or materials discussed in this manuscript.

Ethical approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.

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For this type of study formal consent is not required.

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Pathipati, A.S., Wood, E.H., Lam, C.K. et al. Visual acuity measured with a smartphone app is more accurate than Snellen testing by emergency department providers. Graefes Arch Clin Exp Ophthalmol 254, 1175–1180 (2016). https://doi.org/10.1007/s00417-016-3291-4

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  • DOI: https://doi.org/10.1007/s00417-016-3291-4

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