Digital Tools for the Self-Assessment of Visual Acuity: A Systematic Review

Abstract

Introduction: Numerous digital tools to selfassess visual acuity have been introduced. The recent COVID-19 pandemic underlined the need for high-quality remote care. This review gives a current overview of digital tools for remotely assessing visual function and reports on their accuracy. Methods: We searched the databases of Embase and Pubmed, and systematically reviewed the literature, conforming to PRISMA guidelines. Two preliminary papers were added from medRxiv.org. The main outcome was the agreement of the digital tools with conventional clinical charts, as expressed by mean differences and 95% limits of agreement (95% LoA).Results: Seventeen publications included studies reported on 13 different digital tools. Most of the tools focus on distance visual acuity. The mean differences of the digital tools ranged from -0.08 to 0.10 logMAR, when compared to traditional clinical assessments. The 95% LoA differed considerably between studies: from ± 0.08 logMAR to ± 0.47 logMAR, though the variability was less pronounced for higher visual acuities. Conclusion:The low mean differences between digital visual acuity assessments and reference charts suggest clinical equivalence, though the wide 95% LoA identify a lower precision of digital self-assessments. This effect diminishes in individuals with better visual acuities, which is a common feature of visual acuity assessments. There is great potential for the digital tools to increase access to eye care and we expect the accuracy of the current tools to improve with every iteration in technology development.

The Accuracy of a Web-Based Visual Acuity Self-assessment Tool Performed Independently by Eye Care Patients at Home: Method Comparison Study

“…There are many other telehealth tools for self-assessing visual function available in app stores or on the World Wide Web, though many of these have not been validated [ 12 , 13 ]. A well-established tool is the “Peek Acuity” smartphone app, which was first introduced by Bastawrous et al in 2015 [ 25 ].…”

“…It is one of the key parameters of an ophthalmic (ie, eye care) patient’s evaluation and is conventionally assessed at a clinic using a white chart displaying black optotypes—typically letters or symbols—that patients should correctly identify from a standardized distance [ 11 ]. Multiple tools for self-assessing VA have been introduced over the last decade, though many lack clinical validation [ 12 , 13 ]. Before implementing a telehealth tool in clinical practice, validation research and certification is needed [ 14 ].…”

Analysis of the Reliability and Repeatability of Distance Visual Acuity Measurement with EyeSpy 20/20

“…Unlike other apps, EyeSpy 20/20 completely tests the full line (all 5 letters) at threshold and the full line (all 5 letters) below threshold to allow interpolation between lines, most apps, are not true LogMAR design, use Snellen or other less accepted optotypes, hence a better understanding of the pros and cons are important to understand. A systematic review of some of these apps have been reported elsewhere by Kawamoto et al) 13 and Claessens et al 14 …”

Development and Validation of a Digital (Peek) Near Visual Acuity Test for Clinical Practice, Community-Based Survey, and Research

“…Important missing attributes included adequate evidence of reliability, appropriateness for individuals with low literacy, and timing of the test. Some of the existing digital tests were designed for individuals to use for at-home testing 27 and are often too time consuming to be considered for mass screening or survey (e.g., 172 seconds for PDI Check, or much longer for some tests). 28 Some validated tests were unfortunately no longer available, such as MAVERIC, or were only available in limited regions.…”