At-Home Visual Acuity Tests May Be Comparable to In-Office Measurements

Merina Thomas, MD

New findings supported the use of 3 at-home visual acuity tests in teleophthalmology care during the COVID-19 pandemic, as they appeared comparable within 1 line to in-office visual acuity measurements.

These included publicly available, at-home visual acuity tests that were self-administered under home conditions, including printed charts, mobile phone applications, and web-based tests.

“The COVID-19 pandemic has created an opportunity for expansion of teleophthalmology services due to the necessity of limiting in-person exposures,” wrote study author Merina Thomas, MD, Casey Eye Institute, Oregon Health and Science University. “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.”

As the pandemic increased the use of telehealth technology, investigators noted it was a crucial step to ensure that the quality of ophthalmic care remained optimal. Although a growing research pool has examined these new methods of visual acuity measurement, there is a lack of translation to at-home use, as most were performed in a clinical setting.

The current study looked to compare the at-home visual acuity measurement types to standard in-office testing, in order to validate the accuracy and usability of the tools. Eligible participants were identified from 4 university-based ophthalmology clinics who were ≥18 years and had a VA of ≥20/200 or better in ≥1 eye.

Between July 2020 and March 2021, participants with access to the internet or a mobile device were randomized to receive 2 of 3 at-home VA tests to form the randomized cohort, while those without access to these devices were assigned to a mail-only cohort. They performed the at-home test within 3 days before their standard-of-care in-office appointment and were additionally asked to complete a feedback survey at the end of each test.

During the clinic visit, best-corrected Snellen distance acuity was measured to serve as the reference standard. Visual acuity measurements were converted to logMAR and paired t tests compared the mean acuity of the at-home tests to the in-office and baseline measurements.

From 218 randomized patients, 112 (51.3%) completed 2 of 3 at-home tests, with a mean age of 63.8 years. The mean in-office acuity for randomized participants completing at-home tests was 0.11 logMAR (Snellen equivalent 20/25), with no difference among the 4 clinics.

Data show the mean difference of at-home compared with in-office VA was smallest with the printed chart (-0.07 logMAR; 95% CI, -0.10 to - 0.04). Then, the mobile phone app and website test in comparison to the in-office test had a mean difference of -0.12 (95% CI, -0.15 to -0.09) and -0.13 logMAR (95% CI, -0.16 to -0.10), respectively.

Further, the Pearson correlation coefficient was greatest for the printed chart (0.72; 95% CI, 0.62 - 0.79), while the mobile phone app was 0.58 (95% CI, 0.46 - 0.69) and the website test had a coefficient of 0.64 (95% CI, 0.53 - 0.73).

A total of 28 participants enrolled in the mail-only cohort, while 9 participants (32.1%) completed and submitted results, demonstrating a lower rate of participation compared to the randomized cohort.

However, investigators observed those in the mail-only cohort exhibited more positive responses on the survey (mean score, 3.7 - 4.6) and had greater confidence in the test results compared with the website and printed chart in the randomized cohort (4.4 vs 3.1; P = .007 and 4.4 vs 3.5; P = .04, respectively).

The study, “Validation of Home Visual Acuity Tests for Telehealth in the COVID-19 Era,” was published in JAMA Ophthalmology.