Abstract
The stereoscopic anisotropy is one of the most intriguing phenomena of stereoscopic vision. It shows that the sensitivity to detect 3D horizontal sinusoidal corrugations is much greater than for vertical corrugations for spatial frequencies lower than 1c/deg. Recently, Serrano-Pedraza et al., (2016, IOVS) have shown that the stereoscopic anisotropy increases during childhood and that visual experience probably plays an important role in its development. Here we want to determine the impact that visual experience has throughout life in the stereoscopic anisotropy. We tested two age-groups of 35 participants each. A young group aged 18 to 45 years and an elderly group aged 62 to 90 years. Before the experiment, we measured their stereoacuity using Randot circles. Results show that young participants had lower stereoscopic thresholds (mean=58arcsec, SD=22.85) than elderly participants (mean=80.28arcsec, SD=31.38). In the experiment we measured disparity thresholds for 3D sinusoidal corrugations of 0.1c/deg, with vertical and horizontal orientations. For each participant, we computed the anisotropy index by subtracting the thresholds in logarithmic units of the vertical minus the horizontal corrugation. Results show that stereo thresholds for vertical corrugations are similar for both groups. However, for horizontal corrugations the thresholds are much higher for the elderly group. Therefore, the anisotropy is significantly stronger for the young group (mean=0.667, SD=0.461) than for the elderly group (mean=0.247, SD=0.296). The Pearson correlation between the anisotropy index and age shows a negative and significant correlation (r =-0.49, p=1.65x10-5). This is, as age increases, the anisotropy decreases. In aging, although there is a loss of sensitivity for horizontal corrugations, which is consistent with the reduction of stereoscopic acuity, surprisingly, the sensitivity for vertical corrugations remains stable and does not change through adult life. Thus, we confirm that visual experience plays an important role in the strength of the stereo anisotropy.