An abnormal deviation of 1 eye relative to the other. Many babies have a squint because the mechanism for aligning the eyes has not yet developed. A squint that starts later in childhood is usually due to breakdown of the alignment mechanism. Longsightedness is a common factor. In some cases, the brain suppresses the image from the deviating eye, leading to amblyopia. In adults, squint may be a symptom of stroke, diabetes mellitus, multiple sclerosis, hyperthyroidism, or a tumour. A squint in adults causes double vision. Treatment in children up to 6–7 years may include covering the normal eye with a patch to force the child to use the weak eye. Deviation of the squinting eye may be controlled by glasses and/or surgery. Sudden onset of a squint in adults may have a serious underlying cause and must be investigated promptly.


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