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Jasleen Kaur Jolly, Kristin Juenemann, Heather Boagey, Joanna Moschandreas, Marie Nadsady, Holly Bridge, Robert E MacLaren; Validation of Electronic Visual Acuity Measurement Against Standardised ETDRS Charts In Retinal Disease. Invest. Ophthalmol. Vis. Sci. 2019;60(9):1819.
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With the increase in clinical trials testing therapy for inherited retinal disease there is a need to ensure that outcome measures are both accurate and standardized. The US Food and Drug Administration favors the use of visual acuity (VA) measured using ETDRS logMAR charts. The loss of visual field in rod-cone dystrophies can interfere with visual tracking across the charts leading to increased variability of measurements over time. Electronic visual acuity (EVA) presents the optotype on a screen, removing the tracking element of the task, and may provide a more accurate measure of VA.
VA was measured twice in the right eye of 41 participants with no known eye conditions and 58 participants with rod-cone dystrophy using ETDRS charts, EVA automated single letters and EVA single line presentation (EMMES, USA). Patients also underwent MAIA microperimetry (Centervue, Italy). The tests were compared using a modified Bland-Altman analysis incorporating test-retest values. Spearman correlation was used to understand the implication of the visual field loss on test differences. Patient preference between tests was noted.
In volunteers, performance on the 3 tests was comparable, with coefficients of repeatability of 6.1, 5.3 and 5.2 letters. In the patient group, the repeatability coefficients were higher at 7.4, 7.3 and 7.9 letters. On average, participants read 2-3 letters more on the EVA compared to the charts. However, the specific electronic test made little difference with less than 1 letter difference between the two versions. Eyes were classified as foveal seeing or non-seeing based on the MAIA, with the latter showing wider limits of agreement. For eyes with a non-seeing fovea, there was no evidence that distance to the nearest seeing point impacts the results (r=-0.18, p=0.31). In the seeing eyes, central microperimetry threshold (r=-0.20, p=0.36) and width of vision as measured by continuous seeing points on the MAIA (r=-0.16, p=0.46) were not correlated with difference between tests. The single line presentation was preferred by 51% patients.
Electronic visual acuity may provide more accurate measures of VA than traditional ETDRS charts in patients with visual field loss affecting the central vision. Electronic presentation with a single line of letters was the favored style by patients and should be considered for future interventional clinical trials.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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