At-home tests for measuring visual acuity were shown to be accurate and effective in this study. Photo: Christina @ on Unsplash

Though optometrists have little good to say about the online refraction tests run by corporate interests that actively undermine the value of in-person care, the notion of moving some aspects of vision testing to the home is gaining traction. The COVID-19 pandemic forced healthcare providers, including eyecare professionals, to find ways to reduce the risk of in-office exposure while still providing high-quality care. This led to a renewed interest in telemedicine and its role in patient care. A randomized, comparative effectiveness research study was initiated to determine the validity of at-home tests for visual acuity measurement.

Participants with visual acuity of 20/200 or better were prospectively randomized to self-administer two of three at-home visual acuity tests (printed chart, mobile phone app and website) within three days prior to their standard-of-care clinic visit. They then completed a survey to assess the usability of the at-home tests. During the clinic visit, best-corrected Snellen distance acuity was measured as the reference standard.

The study authors compared results of the at-home and in-office visual acuity tests. They calculated the sensitivity, specificity, positive predictive value and negative predictive value of each at-home test to detect significant visual acuity changes from the in-office baseline.

Of the 218 participants who were randomized, 51.3% completed two of the three at-home tests. The researchers reported a mean in-office visual acuity of 0.11logMAR (Snellen equivalent 20/25) with no significant difference between the tests. They also observed a mean difference (logMAR) between the at-home and in-office tests of -0.07 for the printed chart, -0.12 for the mobile phone app and -0.13 for the website test.

The three at-home visual acuity tests were comparable within one line to in-office visual acuity measurements, the study authors reported. The printed chart had the smallest mean difference and greatest correlation when compared with in-office acuity; however, the researchers noted no statistically significant difference among the three at-home tests.

They also observed that limited access to digital tools was more likely among older participants. While participants reported that they found the tests easy to use and showed interest in future at-home testing, overall feedback indicated that they did not want in-office acuity testing replaced by at-home methods due to accuracy concerns.

This research validated three publicly available, free remote visual acuity tests self-administered under home conditions, according to the study authors.

“The lessons learned in this context may have important implications for rural eye care, as well as eye care in other outreach settings or under-resourced areas,” they concluded. “Visual acuity remains a key clinical data point for eyecare professionals when making diagnostic and treatment decisions.”

Bellsmith KN, Gale MJ, Yang S, et al. Validation of home visual acuity tests for telehealth in the COVID-19 era. JAMA Ophthalmol. March 31, 2022 [Epub ahead of print].