When the eyes are not looking at the same thing in space they are mis-aligned. This mis-alignment is called strabismus and can be pathological or non-pathological in origin. At its onset, strabismus will cause you to see double. If the double-ness is present long enough, the brain will suppress the image of one eye, to make the person see only one image. If this process starts within the first two years of life, ambloypia may develop. Ambloypia, means that there is nothing pathologically wrong with the eye, but the eye does not have good vision because the brain has not allowed the respective visual cortex to develop all its detailed receptive fields. This lack of development is a consequence of the brain suppressing the retinal image to the cortical receptors at the back of the brain. Once the cortical receptors have fully developed, you cannot develop ambloypia from strabismus developing later in life.
Ambloypia can also develop from uncorrected refractive error, even if the eyes are not mis-aligned. The critical period for maximum development of the visual cortex appears to be within the first two years of life. While there is no solid rule, it is fair to say, the longer amblyopia is present the less likely when appropriately treated that significant recovery or a less dense ambloypia can be obtained.
Both concerns, strabismus/uncorrected refractive error and the critical two years of life are part of the argument to recommend eye examinations for infants at about 6 months of age. If the ambloypia is deep enough, a person could be functionally blind out of that eye. As such, they are essentially a monocular person that faces a lifetime of increased risk of having their life turned upside down from an injury to their good eye or from eye disease later in life.
Treatment for strabismus/amblyopia is a complex and among other things is dependent of the patient's age, cause and history. Typically, it may involve eyeglasses, prisms, patching, eye muscle surgery and or visual therapy.
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Last Change: 27 November, 2013