Monocular vision

Monocular vision is vision in which both eyes are used separately. By using the eyes in this way, as opposed by binocular vision, the field of view is increased, while depth perception is limited. The eyes of an animal with monocular vision are usually positioned on opposite sides of the animal's head, giving it the ability to see two objects at once. The word monocular comes from the Greek root, mono for one, and the Latin root, oculus for eye.

Medical conditions related to monocular vision

Monocular vision impairment refers to having no vision in one eye with adequate vision in the other.[1]

Monopsia is a medical condition in humans who cannot perceive three-dimensionally even though their two eyes are medically normal, healthy, and spaced apart in a normal way. Vision that perceives three-dimensional depth requires more than parallax. In addition, the resolution of the two disparate images, though highly similar, must be simultaneous, subconscious, and complete. (After-images and "phantom" images are symptoms of incomplete visual resolution, even though the eyes themselves exhibit remarkable acuity.) A feature article in The New Yorker magazine published in early 2006 dealt with one individual in particular, who, learning to cope with her disability, eventually learned how to see three-dimensional depth in her daily life. Medical tests are available for determining monoptic conditions in humans.

.[2]

Monocular cues

Monocular cues provide depth information when viewing a scene with one eye.

Monocular Vision and Balance

Vision has been known to play an important role in balance and postural control in humans, along with proprioception and vestibular function. Monocular vision affects how the brain perceives its surroundings by decreasing the available visual field, impairing peripheral vision on one side of the body, and compromising depth perception, all three of which are major contributors to the role of vision in balance.[5][6] Studies comparing monocular vision to binocular (two eyes) vision in cataract patients (pre and post surgery),[7] glaucoma patients (compared with healthy age matched controls),[8] and in healthy adults and children (in both binocular and monocular conditions)[9] have all shown to negatively impact balance and postural control than when both are eyes are available. Each of the studied populations still displayed better balance when having only one eye compared to having both eyes closed.

References

  1. http://www.guidedogsqld.com.au/cgi-bin/index.cgi/monocular/mvi Archived December 8, 2006 at the Wayback Machine
  2. Monocular individuals face increased challenges with driving. These specifically relate to depth perception and peripheral vision. Keeney, et al., state, "nationwide, monocularly impaired individuals have seven times more accidents than the general population with which they were compared." He recommends monocularly impaired drivers be denied class 1 licenses, (commercial driver license for transport of people), and that they be warned by their doctors regarding increased risk of accident with driving
  3. Ferris, S. H. (1972). Motion parallax and absolute distance. Journal of experimental psychology, 95(2), 258--63.
  4. O’Shea, R. P., Blackburn, S. G., & Ono, H. (1994). Contrast as a depth cue. Vision Research, 34, 1595-1604.
  5. Berela, J. et al. (2011) Use of monocular and binocular visual cues for postural control in children. Journal of Vision. 11(12):10, 1-8
  6. Wade, M. and Jones, G. (1997) The role of vision and spatial orientation in the maintenance of posture. Physical Therapy. 77, 619-628
  7. Schwartz, S. et al. (2005) The effect of cataract surgery on postural control. Investigative Ophthalmology and Visual Science. 46(3), 920-924
  8. Shabana, N, et al. (2005) Postural Stability in primary open angle glaucoma. Clinical and Experimental Ophthalmology. 33, 264-273
  9. Berela, J. et al. (2011) Use of monocular and binocular visual cues for postural control in children. Journal of Vision. 11(12):10, 1-8

External links

This article is issued from Wikipedia - version of the Thursday, February 25, 2016. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.