Background
Monofixation syndrome is essentially a form of subnormal binocular vision. Monofixation syndrome may also be considered a form of binocular single vision without bifixation due to an absolute scotoma of less than 3º in one eye during binocular vision. Monofixation syndrome can be a primary disorder of binocular vision, or it can be a secondary sensory status from a variety of primary causes.
Monofixation syndrome is a sensory adaptation that is characterized by small-angle strabismus, unilateral facultative central suppression scotoma, and peripheral fusion.
Pathophysiology
The main defect is a central suppression scotoma.
The central retina has small receptive fields and is more sensitive to image blur or image disparity than the peripheral retina. Conditions that cause a suppression scotoma in the central retina but allow for peripheral fusion cause monofixation syndrome.
Some patients seem to have an inherited inability to bifixate.
Epidemiology
Frequency
United States
The prevalence of monofixation syndrome in the general population is 1%.
Age
Monofixation syndrome is recognized mainly in children but can occur at all ages.
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