Color, Depth, and Size


Learning Objectives

Understand what strabismus and amblyopia are.

Understand the results of growing up with these conditions.

Strabismus is a disorder in which both eyes do not line up in the same direction. Therefore, they do not look at the same object at the same time. The most common form of strabismus is known as “crossed eyes.” The oculomotor muscles around each eye allow for both eyes to focus on the same object. When someone has strabismus, these muscles do not work together which causes the eyes to look in different directions. When this occurs, two different images are sent to the brain—one from each eye. This confuses the brain. In children, the brain may learn to ignore or suppress the image from the weaker eye. If the strabismus is not treated by training or surgery, the eye that the brain ignores will never see well and the brain will rely solely on the image from the stronger eye. This loss of vision in one eye is called amblyopia. In most children with strabismus, the cause is unknown and the problem is present at or shortly after birth.

Amblyopia, also called lazy eye, is a type of poor vision that happens in just one eye. It can result from strabismus or anisometropia. Amblyopia develops when there’s a breakdown in how the brain and the eye work together, and the brain can’t recognize the sight from one eye. Normally, the brain uses nerve signals from both eyes to see. But if an eye condition makes vision in one eye worse, the brain may try to work around it. It starts to “turn off” signals from the weaker eye and rely solely on signals from the stronger eye. This creates monocular visions instead of binocular. Amblyopia starts in childhood, and it’s the most common cause of vision loss in kids. However, early treatment works well and usually prevents long-term vision problems. If caught and treated early, stereo vision can develop normally (Fig.10.8.1).


Fig.10.8.1. Treatment for Amblyopia. This figure shows a child wearing an eye patch attempting to cure amblyopia. Using an eye patch helps to strengthen the non-dominant eye and forces the brain to receive images from that visual field. (Provided by: National Eye Institute, National Institutes of Health. License: CC-BY-4.0.)


A.D.A.M. Inc., MEDLINE, Strabismus
Provided by: US National Library of Medicine
License: PDMNational Eye Institute, Amblyopia (Lazy Eye)
Provided by: National Institutes of Health
License of original source: PDM



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Introduction to Sensation and Perception Copyright © 2022 by Students of PSY 3031 and Edited by Dr. Cheryl Olman is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted.

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