An app created by NYU seems to perform as a reliable measure of visual acuity.
An app created by NYU seems to perform as a reliable measure of visual acuity. Photo: NYU Langone Health. Click image to enlarge.

Though optometrists have legitimate concerns about the limitations of online vision tests, this method of measuring visual acuity (VA) continues to evolve and can be especially helpful in telehealth settings. In a recent study, researchers assessed user satisfaction and usability with the one such application from New York University’s Langone Health medical center.

Using a smartphone app, VA was taken from 244 eyes of 125 participants 18 and older using the clinical standard Rosenbaum near card and the NYU Langone Eye Test app, with each test performed twice to measure reliability. Those with a VA of 20/400 (1.3 logMAR) or worse were excluded.

The researchers then assessed the extent of agreement between the results of the NYU Langone Eye Test app and Rosenbaum card, as well as the test-retest reliability of each method. A satisfaction survey and patient interview were developed to measure usability and acceptability.

The average difference between VA measured using the application was within 2.9 ETDRS lines (0.029 logMAR) of the Rosenbaum card’s measured VA. Additionally, the subgroup analysis showed that the agreement was within 1.5 ETDRS lines (0.155 logMAR) in participants tested under experimental conditions, which is comparable to the clinical standard measures that cannot reliably measure a one-line change in VA, according to the study authors.

“The primary benefit of this app is that it allows for the patient to collect more data about their vision and more flexibility in the collection of this data,” they explained in their paper. “Potential applications of this app suggested by our patients include post-op care, post-traumatic eye injury monitoring and as a screening tool that can be used to determine the need for an in-person vs. teleophthalmology visit. Patients also did not express security concerns, and they enjoyed the convenience and accessibility benefits that a mobile VA app allows.”

The NYU Langone Eye Test also demonstrated high test-retest reliability, which the investigators noted was “more valuable than a one-to-one agreement with the Rosenbaum card.”

Overall, the study showed that the NYU Langone Eye Test application is a user-friendly, accurate and reliable measure of near VA. “The app’s integration with the electronic health record, accessibility and easy interpretation of results, among other features, make it ideal for telemedicine use,” the team concluded.

Weaknesses identified by patients primarily dealt with the wifi-dependent nature of the app, potential accuracy concerns, face-to-face interaction loss and applicability and usefulness for patients across the board.

Iskaner M, Galen H, Sood S, et al. Validation of the NYU Langone Eye Test application, a smartphone-based visual acuity test. Ophthalmol Sci. June 3, 2022. [Epub ahead of print].