Seeing the World Like Never Before: Human stereovision through perfect optics

Stereovision is the ability to perceive fine depth variations from small differences in the two eyes’ images. Using adaptive optics, we show that even minute optical aberrations that are not clinically correctable, and go unnoticed in everyday vision, can affect stereo acuity. Hence, the human binocular system is capable of using unnaturally fine details that are not encountered in everyday vision. More importantly, stereoacuity was still considerably variable even with perfect optics. This variability can be attributed to neural adaptation. Our visual system tries to compensate for these aberrations through neural adaptation that optimizes stereovision when viewing stimuli through one’s habitual optics. However, the same adaptation becomes ineffective when the optics are changed, even if improved. Beyond optical imperfections, we show that stereovision is limited by neural adaptation to one’s own optics. Significance statement Humans, and animals with front-facing eyes, view the world from slightly different vantage points. This creates small differences in the left and right images that can be utilized for fine depth perception (stereovision). Retinal images are also subject to imperfections that are often different in the optics of the two eyes. Using advanced optical correction techniques, we show that even the smallest imperfections that escape clinical detection affect stereovision. We also find that neural processes become adapted to a person’s own optics. Hence, stereovision is directly impacted by the optics of the eyes, and indirectly via neural adaptation. Since the optics change over the lifespan, our results imply that the adult binocular system is adaptable with possibilities for binocular rehabilitation. ### Competing Interest Statement The authors have declared no competing interest.