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. 2022 Oct;36(10):2057-2061.
doi: 10.1038/s41433-021-01760-2. Epub 2021 Aug 30.

Clinical validation of a novel web-application for remote assessment of distance visual acuity

Arun James Thirunavukarasu  1   2 , Deborah Mullinger  3 , Remi Mohan Rufus-Toye  3   4 , Sarah Farrell  3 , Louise E Allen  3
Affiliations

Clinical validation of a novel web-application for remote assessment of distance visual acuity

Arun James Thirunavukarasu et al. Eye (Lond). 2022 Oct.

Abstract

Background/objectives: Ophthalmic disorders cause 8% of hospital clinic attendances, the highest of any specialty. The fundamental need for a distance visual acuity (VA) measurement constrains remote consultation. A web-application, DigiVis, facilitates self-assessment of VA using two internet-connected devices. This prospective validation study aimed to establish its accuracy, reliability, usability and acceptability.

Subjects/methods: In total, 120 patients aged 5-87 years (median = 27) self-tested their vision twice using DigiVis in addition to their standard clinical assessment. Eyes with VA worse than +0.80 logMAR were excluded. Accuracy and test-retest (TRT) variability were compared using Bland-Altman analysis and intraclass correlation coefficients (ICC). Patient feedback was analysed.

Results: Bias between VA tests was insignificant at -0.001 (95% CI -0.017 to 0.015) logMAR. The upper limit of agreement (LOA) was 0.173 (95% CI 0.146 to 0.201) and the lower LOA -0.175 (95% CI -0.202 to -0.147) logMAR. The ICC was 0.818 (95% CI 0.748 to 0.869). DigiVis TRT mean bias was similarly insignificant, at 0.001 (95% CI -0.011 to 0.013) logMAR, the upper LOA was 0.124 (95% CI 0.103 to 0.144) and the lower LOA -0.121 (95% CI -0.142 to -0.101) logMAR. The ICC was 0.922 (95% CI 0.887 to 0.946). 95% of subjects were willing to use DigiVis to monitor vision at home.

Conclusions: Self-tested distance VA using DigiVis is accurate, reliable and well accepted by patients. The app has potential to facilitate home monitoring, triage and remote consultation but widescale implementation will require integration with NHS databases and secure patient data storage.

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Conflict of interest statement

Louise Allen is the inventor and developer of DigiVis and founding director of Cambridge Medical Innovation Ltd. An international patent application for DigiVis’ distance calibration system has been made by Cambridge Enterprise Ltd.

Figures

Fig. 1
Fig. 1
Screenshots from the DigiVis web-app during testing, from the larger screen (a) and handheld device (b). Patients select which optotype is indicated by arrows on the larger screen, from a range of choices on the handheld device.
Fig. 2
Fig. 2
Histogram and overlain density plot illustrating the distribution of age in the participating population.
Fig. 3
Fig. 3. Bland-Altman plots comparing DigiVis and clinical measurements (right), and repeated DigiVis measurements (left).
The bias and 95% LOA are indicated by dashed lines, whilst shaded 95% confidence intervals for each are bounded by dotted lines.
See this image and copyright information in PMC

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