Remote refraction has had a stormy history in eye care so far, with online vision exam services typically falling far short of what an in-person exam conducted by an eye care provider can achieve. Among their shortcomings is a lack of a validated method to measure visual acuity (VA) remotely. Looking to close this gap, a team of ophthalmologists at Vanderbilt University recently found that self-administered, at-home ETDRS VA testing can achieve results equivalent to a standard technician-administered VA test in-clinic when patients follow appropriate protocols.
This prospective cohort study evaluated 209 eyes of 108 patients. All participants received instructions and a printout ETDRS vision chart calibrated for five feet. Patients completed the VA test at home before the in-person appointment, where their VA was measured with a standard ETDRS chart, and the two results were compared. Patients also filled out a survey about the ease of testing and barriers to completion.
Mean adjusted VA letter score difference between at-home and in-clinic testing was 4.1 letters, which was within the seven-letter equivalence margin, the researchers noted. Average unadjusted VA scores in-clinic were 3.9 letters greater than at-home scores. The absolute difference was 5.2 letters. Overall, 98% of patients agreed that the home test was easy to perform.
The researchers were careful not to overstate the applicability of such an approach, concluding that “the home test should not be used to replace in-person assessments when indicated but rather used to delay well visits or as a tool that enhances the value of teleophthalmology visits” and noting that “the home test is not for everyone, particularly patients with VA <20/200. Patients who have severe eye disease need an in-person appointment to monitor their progression.” Still, they believe the test could enhance the quality of telehealth visits in eye care for routine care and those patients undergoing screening for diabetic retinopathy or glaucoma or have stable well-managed eye conditions. “Thus, the home test should not be used to replace in-person assessments when indicated but rather used to delay well visits or as a tool that enhances the value” of telehealth eye consults.”
Siktberg J, Hamdan S, Liu Y, et al. Validation of a standardized home visual acuity test for teleophthalmology. Ophthalmol Sci. March 10, 2021. [Epub ahead of print].