Effects of long-term neural adaptation to habitual sspherical aberration on through-focus visual acuity in adults

We investigated how long-term visual experience with habitual spherical aberration (SA) influences subjective depth of focus (DoF). Nine healthy cycloplegic eyes with habitual SAs of different signs and magnitudes were enrolled. An adaptive optics (AO) visual simulator was used to measure through-focus high-contrast visual acuity after correcting all monochromatic aberrations and imposing + 0.5 μm and - 0.5 μm SAs for a 6-mm pupil. The positive (n = 6) and negative (n = 3) habitual SA groups ranged from 0.17 to 0.8 μm and from - 1.2 to - 0.12 μm for a 6-mm pupil, respectively. Although all optical conditions were identical, and the subjective DoFs were expected to be the same for all participants, the DoFs of individuals differed between the positive and negative habitual SA groups. For the positive habitual SA group, the mean DoF with positive AO-induced SA (2.14 D) was larger than that with negative AO-induced SA (1.88 D); for the negative habitual SA group, a smaller DoF was measured with positive AO-induced SA (1.94 D) than that with negative AO-induced SA (2.14 D). Subjective DoF tended to be larger when the induced SA in terms of sign and magnitude was closer to the participant's habitual SA. Our findings suggest that neural adaptation to habitual SA compensated for optical blur at multiple object distances, perceptually expanding DoF. As a result, the outcomes of optical treatments for presbyopia may differ due to the neural compensation mechanism influenced by an individual's visual experience with their habitual optics.