Remote Vision Testing: Validation Of A Simple Home-Printable Vision Screening Test for Telemedicine

ImportanceHundreds of thousands of ophthalmology clinic appointments have been converted to telemedicine assessments. Here we validate a simple paper vision test (the Home Acuity Test) for ophthalmology telemedicine appointments, which can be used by people who are digitally excluded.ObjectiveTo determine the repeatability of vision measured on the Home Acuity Test, and the agreement between the Home Acuity Test and the last in-clinic visual acuity.DesignBland-Altman analysis of the Home Acuity Test chart, compared to the last measured visual acuity on a standard clinical test.SettingRoutine outpatient ophthalmology telemedicine clinics in a large specialist eye hospital.Participants50 control subjects with no eye disease and 100 consecutive adult ophthalmology outpatients from strabismus and low vision telemedicine clinics. Participants were excluded if they reported subjective changes in their vision.Main outcomes and measuresFor control participants, test/retest variability of the HAT and agreement with standard logMAR visual acuity measurement. For ophthalmology outpatients, agreement with the last recorded clinic visual acuity and with ICD-11 visual impairment category.Results50 control subjects and 100 ophthalmology patients with a wide range of disease were recruited. For control participants, Home Acuity Test test/retest variability was -0.012 logMAR (95% CI: -0.25 to 0.11 logMAR). Agreement with standard vision charts was -0.14 logMAR, with a 95% confidence interval of -0.39 to +0.12 logMAR. For ophthalmology outpatients, agreement in visual acuity was -0.10 logMAR (one line on a conventional logMAR sight chart), with the Home Acuity Test indicating poorer vision than the previous in-clinic test. The 95% confidence interval for difference was –0.44 to +0.24 logMAR. Agreement in visual impairment category was good for patients (Cohen’s k test, k = 0.77 (95% CI, 0.74 to 0.81), and control participants (Cohen’s k test, k = 0.88 (95% CI, 0.88 to 0.88).Conclusions and relevanceThe Home Acuity Test can be used to measure vision by telephone for a wide range of ophthalmology outpatients with diverse conditions, including those who are severely visually impaired. Test/retest variability is low and agreement in visual impairment category is good.