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Optics and neural adaptation jointly limit human stereovision

Significance Humans, and other animals, have eyes laterally displaced on the head that view the world from slightly different vantage points to create small differences in the left and right images. These differences are utilized for depth perception (stereovision). Retinal images are also subject to optical imperfections, often different in the two eyes. Using advanced optical techniques, we show that even the smallest imperfections escaping clinical detection affect stereovision. Our data also suggest that neural processes become acclimated to a person’s own optics. Hence, stereovision is directly affected by the eyes’ optics and indirectly via neural adaptation. Because the optics change over the lifespan, the implication is that the adult binocular system is adaptable, pointing to the potential for binocular rehabilitation. 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 fine details that are not experienced in everyday vision. Interestingly, stereo acuity varied considerably across individuals even when they were provided identical perfect optics. We also found that individuals’ stereo acuity is better when viewing with their habitual optics rather than someone else’s (better) optics. Together, these findings suggest that the visual system compensates for habitual optical aberrations through neural adaptation and thereby optimizes stereovision uniquely for each individual. Thus, stereovision is limited by small optical aberrations and by neural adaptation to one’s own optics.