Strabismus is a visual defect in which the eyes are misaligned and point in different directions, inward or outward (crossed eyes). The disorder is common among children, but is also present in approximately 1 to 2 percent of the adult population – usually as a condition that began in childhood or acquired, most commonly as a result of thyroid eye disease or cranial nerve palsies.
Eye misalignment causes the brain to receive two different visual messages. In young children, the brain may begin to “ignore” the image sent by the deviating eye while highly detailed visual information may be processed from the straight eye. This may result in amblyopia.
Strabismus is also frequently accompanied by defective or absent binocular vision, which is characterized by reduced 3-D vision, resulting in impaired depth perception.
Parents should realize that children usually do not outgrow strabismus and that treatment, whether glasses, exercises, or eye muscle surgery, is most effective when initiated early in a child’s development.
Once the visual system is developed, as in older children or adults, strabismus may produce double vision, eye strain, discomfort in reading, and headaches. Effective treatment is often available.
Adults without a previous history of childhood strabismus should have a careful evaluation to rule out the possibility of medical or neurological causes, such as diabetes, thyroid disease, myasthenia gravis, brain tumor, or stroke.