Poster Session: Assessing the relationship between the cone mosaic and AO-corrected visual acuity.

Using adaptive optics (AO), it is possible to deliver near diffraction-limited stimuli to the human retina to assess the relationship between the cone mosaic and visual function. Here we sought to establish device-specific control data for future studies of individuals with retinal disease. We used AOSLO to quantify the cone mosaic and measure visual acuity in the dominant eye of 18 individuals (7M, 11F; 15-67 years) without retinal pathology. Average density at the cone density centroid was 186,925 cones/mm^2. Visual acuity was assessed using an AO-corrected Snellen E presented via a QUEST-driven four-alternative forced-choice task. The mean observed acuity across individuals was -0.23 (±0.08) logMAR. We compared observed acuity to that predicted by foveal cone spacing, using the average spacing within a given individual's 95% bivariate contour ellipse area centered on an estimated preferred-retinal fixation locus. The mean (± SD) predicted acuity across individuals was -0.30 (±0.03) logMAR. The ratio of observed:predicted acuity ranged from 1.54 to 0.30 (average = 0.78). Six individuals had observed acuity equal to or better than that predicted by their foveal cone spacing, while the other 12 had an observed acuity worse than that predicted by their foveal cone spacing. These results warrant further examination of factors contributing to the variation of AO-based acuity measures, including experimental differences, internal response bias, and other biological factors.