Helen Treankler¹, Mina Gaffney,³, Mohammed Herzallah², Adam Greenberg⁴; ¹Medical College of Wisconsin, ²Marquette University

During standard visual acuity (VA) testing, participants are asked to read aloud (row-by-row) a series of letters on a chart containing 14 rows (5 letters each) of logarithmically-scaled visual angle. The tumbling E ETDRS chart is comprised of a series of E’s in 4 possible orientations via rotations of 0, 90, 180, and 270 degrees. Participants are asked to report the orientation of each E, and VA is typically reported via the line of the smallest E’s, in which the majority is correctly identified. We hypothesized that a psychophysical approach to VA measurement would yield a more precise outcome metric and could potentially reduce bias, quantify uncertainty, and differentiate real changes above-and-beyond normal variability. To test this, we developed a digital version of the traditional tumbling E task that uses a staircase paradigm to display a range of E sizes (with orientation randomized), generating psychometric curves from which acuity thresholds can be estimated. Participants performed two experiments at a distance of 2 meters: one with the traditional analog chart and one with our digital task. The digital task contained 280 total trials in two blocks, each containing 3 or 4 interleaved staircases via the QUEST algorithm. Each experiment took approximately 10-15 minutes to complete. Results from both experiments were converted to LogMAR acuity. Our digital method allows for a more continuous measurement of VA rather than assessing at discrete levels. The digital test demonstrated superior precision over analog testing, with adaptive staircases producing tighter clustering and more stable threshold estimates for detecting subtle acuity changes. Our psychophysical approach to measuring acuity demonstrates the potential to improve clinical assessment of VA while preserving patient encounter time, and to potentially identify deficits beyond VA when incorporating reaction time.