JAMA Ophthalmology Journal Club Slides: Development and Validation of a Smartphone Visual Acuity Test Bastawrous A, Rono HK, Livingstone IAT, et al. Development and validation of a smartphone-based visual acuity test (Peek Acuity) for clinical practice and community-based fieldwork. JAMA Ophthalmol. Published online May 28, 2015. doi:10.1001/jamaophthalmol.2015.1468.

Introduction Visual acuity is the most frequently performed measure of visual function in clinical practice. The majority of people with visual impairment are living in low- and middle-income countries. Objective To design and validate a smartphone-based visual acuity test that is not dependent on familiarity with symbols or letters commonly used in the English language.

Introduction Peek Acuity and ETDRS

Methods Study Design Validation study comparing results from smartphone-based Peek Acuity to Snellen acuity (clinical normal) charts and the Early Treatment Diabetic Retinopathy Study (ETDRS) logMAR chart (reference standard). This study was nested within the 6-year follow-up of the Nakuru Eye Disease Cohort in central Kenya. Participants 300 adults aged 55 years and older recruited consecutively from the Nakuru Eye Disease Cohort Study. Data Analysis Visual acuity scores for each test: ETDRS logMAR, Snellen acuity, and Peek Acuity, compared in terms of test-retest variability and measurement time. Limitations Not possible to test ETDRS logMAR in participants’ homes as with other tests. Confined to older adults.

Methods

Results The 95% confidence limits for test-retest variability of smartphone-based acuity data were ±0.033 logMAR. The mean difference between the smartphone-based test and the ETDRS chart was 0.07 (95% CI, 0.05-0.09) logMAR; the mean difference between the smartphone-based test and Snellen acuity data was 0.08 (95% CI, 0.06-0.10) logMAR. Smartphone-based test acuities agreed well with those of the ETDRS and Snellen charts. The agreement of Peek Acuity and the ETDRS chart was greater than the Snellen chart with the ETDRS chart (95% CI, 0.05-0.10; P = .08). The local Kenyan community health care workers readily accepted the Peek Acuity smartphone test; it required minimal training and took no longer than the Snellen test (77 seconds vs 82 seconds; 95% CI, 71-84 seconds vs 73-91 seconds, respectively; P = .13).

Results Results of the 8 Pairwise Comparisons of the Right Eye Showing Bland-Altman and Pearson Correlation Analysis

Difference of the Average Results Difference of the Average

Comment This study found Peek Acuity to be comparable in accuracy to the ETDRS chart. Peek Acuity had similar repeatability to that previously reported for other acuity tests in repeatability studies. Peek Acuity was performed in a clinically acceptable time and was found to not be slower than the clinically preferred Snellen acuity test. Peek Acuity had greater portability and ease of use compared with other testing modalities.

Comment The ubiquity of smartphones among health care professionals and increasing penetration, particularly in low- and middle-income countries, provides potential for delivering high-quality, objective, repeatable, and acceptable vision testing throughout the world. With most of the world’s blind people living in low-income countries, the need for tools to increase early detection and appropriate referral are vital if the prevalence of blindness and visual impairment is to be reduced.

Conflict of Interest Disclosures Contact Information If you have questions, please contact the corresponding author: Andrew Bastawrous, MCROphth, International Centre for Eye Health, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7Ht, England (andrew.bastawrous@lshtm.ac.uk). Funding/Support The Nakuru Eye Disease Cohort Study was jointly funded by the Medical Research Council (MRC) and the Department for International Development (DFID) under the MRC/DFID Concordat agreement and Fight for Sight. Additional funding supporting the study (equipment and field staff) were provided by the International Glaucoma Association and the British Council for the Prevention of Blindness. The Technology for Eye Health project is funded by the Queen Elizabeth Diamond Jubilee Trust. Conflict of Interest Disclosures Drs Bastawrous and Livingstone and Mr Jordan have a patent pending on the Peek Vision retina hardware. No other disclosures were reported.