Evaluation of a Home-Printable Vision Screening Test for Telemedicine

Abstract

Importance: Many ophthalmology appointments have been converted to telemedicine assessments. The use of a printed vision chart for ophthalmology telemedicine appointments that can be used by people who are excluded from digital testing has yet to be validated.

Objectives: To evaluate the repeatability of visual acuity measured using the Home Acuity Test (HAT) and the agreement between the HAT and the last in-clinic visual acuity.

Design, setting, and participants: This diagnostic study was conducted from May 11 to 22, 2020, among 50 control participants and 100 adult ophthalmology outpatients who reported subjectively stable vision and were attending routine telemedicine clinics. Bland-Altman analysis of corrected visual acuity measured with the HAT was compared with the last measured in-clinic visual acuity on a conventional Early Treatment Diabetic Retinopathy Study logMAR chart.

Main outcomes and measures: For control participants, repeatability of the HAT and agreement with standard logMAR visual acuity measurement. For ophthalmology outpatients, agreement with the last recorded in-clinic visual acuity and with the International Classification of Diseases and Related Health Problems, 11th Revision visual impairment category.

Results: A total of 50 control participants (33 [66%] women; mean [SD] age, 36.0 [10.8] years) and 100 ophthalmology patients with a wide range of diseases (65 [65%] women; mean [SD] age, 55.3 [22.2] years) were recruited. For control participants, mean (SD) test-retest difference in the HAT line score was -0.012 (0.06) logMAR, with limits of agreement (LOA) between -0.13 and 0.10 logMAR. The mean (SD) difference in visual acuity compared with conventional vision charts was -0.14 (0.14) logMAR (range, -0.4 to 0.18 log MAR) (-7 letters) in controls, with LOA of -0.41 to 0.12 logMAR (-20 to 6 letters). For ophthalmology outpatients, the mean (SD) difference in visual acuity was -0.10 (0.17) logMAR (range, -0.5 to 0.3 logMAR) (1 line on a conventional logMAR sight chart), with the HAT indicating poorer visual acuity than the previous in-clinic test, and LOA of -0.44 to 0.23 logMAR (-22 to 12 letters). There was good agreement in the visual impairment category for ophthalmology outpatients (Cohen κ = 0.77 [95% CI, 0.74-0.81]) and control participants (Cohen κ = 0.88 [95% CI, 0.88-0.88]).

Conclusions and relevance: This study suggests that the HAT can be used to measure visual acuity by telephone for a wide range of ophthalmology outpatients with diverse conditions. Test-retest repeatability is relatively high, and agreement in the visual impairment category is good for this sample, supporting the use of printed charts in this context.

Figure 1.. Difference Between Visual Acuity Measured With Conventional and Home Acuity Test (HAT) Charts and Repeatability of HAT for 50 Control Participants

A, Difference between visual acuity measured with conventional and HAT charts for 50 control participants. B, Repeatability of HAT for 50 control participants using letter-by-letter scoring. N indicates the number of individuals per data point in the plot; VA, visual acuity; the gray-shaded bands, 95% CIs; solid horizontal lines, mean difference across measurements; dashed horizontal lines, reference x-axis corresponding to zero differences between measurements; and vertical lines with limit lines, 95% CIs on the limits of agreement.

Figure 2.. Difference Between Visual Acuity (VA) Measured With Conventional and Home Acuity Test (HAT) Charts for 100 Ophthalmology Outpatients

N indicates the number of individuals per data point in the plot; the gray-shaded band, 95% CI; solid horizontal line, mean difference across measurements; dashed horizontal line, reference x-axis corresponding to zero differences between measurements; and vertical lines with limit lines, 95% CIs on the limits of agreement.

Figure 3.. Agreement in Clinical Categorization Between Home Acuity Test (HAT) and the Last In-Clinic Visual Acuity Measurement

N indicates the number of individuals per cell in the grid plot; and the dashed diagonal line, the identity line corresponding to perfect agreement between measurements.