Telemedicine has aided social distancing measures in the clinic, but more creative solutions and innovations are still needed before it can be a more all-encompassing substitute for a physical examination. A recent study assessed ways of testing visual acuity at home for telemedicine visits and identified three apps that may be of use.1
At-home visual acuity testing is a “simple, inexpensive and useful adjunct to ophthalmic teleconsultations,” the researchers pointed out in their paper.1 Currently, there are three types of tools available: printed optotypes, web-based tools and mobile applications. They noted that printed optotypes are not ideal since viewing distance, ambient lighting and even the printing calibration itself can affect the accuracy of the results.1 The web-based tools that were accurate, as assessed by another study, required payment to view the results.2 The researchers turned to mobile apps.
They identified the top 50 apps on Google Play and Apple Apps, of which 24 of the total 100 met the following criteria: the app loaded, tested for visual acuity and did not require purchase or external devices. Sixteen apps (67%) tested near vision, five (21%) tested distance vision and three (13%) offered options for both near and distance vision testing. Five (21%) of the apps also offered a method of optotype size calibration and three (13%) were clinically validated. The investigators defined this evidence of clinical validation as “objective evidence that the apps meet the needs and intended use as a medical device through published clinical trials.” None of the apps were registered under the FDA, but one (Peek Acuity Pro) was a CE-registered, Class 1 medical device.1
“Our results show that despite a large number of apps available on the market today, only a few are potentially useful in the context of ophthalmic teleconsultations and in nonophthalmic settings where visual acuity testing is indicated,” the researchers said. “Interestingly, only eight apps (33%) of the 24 tested actually presented the visual acuity in a clinically useful measure. The remaining sixteen apps (67%) used scales such as ‘star’ or ‘smiley face’ rating systems, or numbers of correct answers displayed as a percentage or a fraction; these measures cannot be reliably used to monitor disease progression or to triage patients in eye casualty settings.”1
Ultimately, three apps fulfilled the researchers’ criteria for suitability for clinical practice: Peek Acuity Pro (Peek Vision), LooC (LooC GmbH), which hasn’t been clinically validated, and for testing distance vision, an Apple Watch, computer or laptop connected to the same Wi-Fi network as the phone. For this method, users type in a URL and calibrate the phone against the other device before measuring visual acuity.1
The researchers concluded that Peek Acuity Pro and LooC have the potential to be incorporated into clinical practice. “These apps can be used by patients to self-test their visual acuity in the context of ophthalmic teleconsultations to aid virtual triage and prompt further investigations,” the researchers said. “Further, these apps can be effectively used in resource-constrained settings where vision impairment is more prevalent and there is low access to ophthalmic services.” An added benefit is that these three apps are free to download and available on major operating systems like Google and Apple. The researchers wrote that further clinical validation of individual apps and improved governance of health apps and cohort management systems, particularly for monitoring chronic eye conditions, is needed to fully integrate these apps into existing care pathways.1
1. Kawamoto K, Stanojcic N, Li JO, et al. Visual acuity apps for rapid integration in teleconsultation services in all resource settings: a review. Asia Pac J Ophthalmol (Phila). February 8, 2021. [Epub ahead of print].
2. Yeung W, Dawes P, Pye A, et al. eHealth tools for the self-testing of visual acuity: a scoping review. NPJ Digit Med. 2019;2:82.