stereopsis
Stereopsis is the visual appreciation of three dimensions during binocular vision.1 Horizontally disparate retinal elements are stimulated at the same time, and fusing the two images yields a single impression seen in depth, provided the fused image lies within Panum's area.1
The separation of the two eyes in space gives each retina a slightly different image of the same object, and that difference is retinal disparity.2 A disparity larger than Panum's fusional area produces physiologic diplopia, and a smaller disparity produces a three-dimensional percept.2 Fusion lets the observer see a single object from two retinal images, and stereopsis uses the disparity between those images to judge relative depth.2
Stereopsis is impaired if the eyes are misaligned, if only one eye is fully functional, or if the cortical connections are damaged or incompletely developed.2 Its presence or absence is an important indicator of binocularity in patients with ocular motility disorders, and patients with essential infantile esotropia are stereoblind or have markedly reduced stereopsis.3
More detail
Most infants first show stereopsis between 2 and 6 months of age, with an average onset at 4 months.2 After that abrupt onset, the stereoacuity threshold falls rapidly to 1 minute of arc within a few weeks.2 In childhood strabismus of later onset, and in adults with acquired strabismus, reestablishing stereopsis is an important therapeutic goal.3
Sources (8)
- Color Atlas of Ophthalmology (2009), ch. 17
- Duckman, Visual Development, Diagnosis, and Treatment of the Pediatric Patient, ch. 7
- von Noorden and Campos, Binocular Vision and Ocular Motility, ch. 15
- Bishop, P.O. 1989. Vertical disparity, egocentric distance and stereoscopic depth constancy: a new interpretation. Proceedings of the Royal Society of London. Series B, Biological Sciences, 237(1288), pp.445-457.
- Noorden, G.K. and Campos, E.C. 2002. Binocular vision and ocular motility: theory and management of strabismus. 6th ed. St. Louis: Mosby.
- Rutstein, R. and Daum, K. 1997. Anomalies of Binocular Vision: Diagnosis & Management. St. Louis: Mosby.
- Steinman, S.B., Steinman, B.A. and Garzia, R.P. 2000. Foundations of binocular vision: a clinical perspective. New York: McGraw-Hill.
- Webvision. 2005. The Perception of Space. [online] Available at: <https://www.ncbi.nlm.nih.gov/books/NBK11512/> [Accessed 6 May 2024]. secondary
Reviewed October 2026