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

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.

Novel web application for self-assessment of distance visual acuity to support remote consultation: a real-world validation study in children

“…Despite the limitations of the study, the results indicate that self-testing with DigiVis is comparable with ageappropriate VA assessment by a trained examiner in this childhood population, agreeing with our findings in a wider population containing older children and adults. 14 The accuracy of VA assessment is dependent on viewing distance, correct use of glasses and effective occlusion. Confidence in home testing results may be improved by synchronising testing with remote consultation, using the share screen function of medical video conferencing software.…”

Analysis of the Reliability and Repeatability of Distance Visual Acuity Measurement with EyeSpy 20/20

“…One such system is called PEEK acuity as developed by Bastawrous group 2 and has been validated against ETDRS chart and Snellen acuity chart with good repeatability and accuracy. More recently, another system called DigiVis a smartphone or tablet-based system has been validated with accuracy and repeatability 3 as well. The repeatability of visual acuity measurements in the current study are repeatable and similar to that of Bastawrous 2 with a test–retest variability using a smartphone at ±0.029 logMAR and that of Thirunavukarasu 3 who reported a 95% CI of −0.017 to 0.015 logMAR with a Digivis system.…”

“…More recently, another system called DigiVis a smartphone or tablet-based system has been validated with accuracy and repeatability 3 as well. The repeatability of visual acuity measurements in the current study are repeatable and similar to that of Bastawrous 2 with a test–retest variability using a smartphone at ±0.029 logMAR and that of Thirunavukarasu 3 who reported a 95% CI of −0.017 to 0.015 logMAR with a Digivis system. PEEK uses an adaptive algorithm but is limited to tumbling E (which is not the US standard), it is available only on Android platform, and the test distances are not customizable.…”

Diagnostic accuracy of online visual acuity testing of paediatric patients

“…Other studies have found LOAs ranging from ± 0.08 to ± 0.49 logMAR 6, 16-23 . Studies varied in the number of aspects changed between reference and index sessions, for example separating tests in time 4,16,20,22,23 , conducting tests in different settings 4,16,18,20,22,23 , using different testers 4,16,18,20,21 , and/or comparing supervised testing with unsupervised self testing 18,20,21,23 , as well as assessing different tests. Each changed aspect widens the LOAs: the current study changed test and setting, undertook tests several days apart and often used a different tester.…”