Home acuity test shows high repeatability, agreement with in-clinic visual acuity
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A printable home vision test accurately measured visual acuity in ophthalmology outpatients and displayed high test-retest repeatability in a diagnostic study.
“We are excited to be developing a simple test that clinicians can use to estimate the level of vision in patients who can’t attend in-person appointments, which has the potential to be a great addition to the telephone and online appointments we provide at Moorfields, and we are encouraged by our results,” study co-author Michael D. Crossland, PhD, told Healio/OSN.
Researchers evaluated the repeatability of visual acuity measurements in 100 adult ophthalmology outpatients using a home acuity test (HAT), which was developed to measure visual acuity remotely for those who could not attend in-clinic ophthalmology appointments due to COVID-19, as well as the agreement of HAT outcomes with the last recorded in-clinic visual acuity for each outpatient. The repeatability of the test and its agreement with standard logMAR visual acuity measurements in 50 control participants were also assessed.
For ophthalmology outpatients, the mean difference in visual acuity was 0.10 logMAR, or one line on a conventional logMAR sight chart, between the HAT outcomes and the last in-clinic visual acuity assessment. The HAT indicated poorer vision than the previous in-clinic test.
In the control participants, the mean visual acuity in the test eye was 0.15 logMAR. The mean difference in visual acuity was 0.14 logMAR, less than two lines on a logMAR sight chart, with the clinic chart showing better vision than the HAT. Bland-Altman analysis showed a limits of agreement (LOA) interval between 0.41 and 0.12.
Researchers found the HAT displayed high test repeatability. When using letter-by-letter scoring between two versions of the HAT, the mean difference in visual acuity was 0 letters, with an LOA between 1.3 and 1.3 letters.
“The test can be downloaded free of charge from homeacuitytest.org, doesn’t require any specialist equipment and can be posted to people who are not able to access the internet at home,” Crossland said.
Perspective
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Although circumscribed in its breadth, this is an important study, not just because of the restrictions imposed by COVID-19, but also due to the probable future market shift in ophthalmology.
Specifically, it is likely that we will see a continued desire for patients to receive as much care as possible as conveniently and as close to, or in, the home as possible. The restrictions imposed by COVID-19 have accelerated the market force that had been slowly evolving even before the pandemic.
The study found a very good correlation between the home acuity test (HAT) and a participant’s last known visual acuity. When a difference in visual acuity was evident, it was more likely to be worse in the HAT by approximately one line. The study was performed with patients who reported that their visual acuity was the same. It is possible that some people, even if asymptomatic, had a true change of visual acuity.
The study would have been stronger if the authors had been able to test the acuity at home and then shortly thereafter test it formally in person. However, given the restrictions imposed due to the pandemic during which this study was done, it was extremely well performed.
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