Strabismus is a visual defect in which the eyes are misaligned and point in different directions. 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, eye drops, 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.
Brain disorders which may cause visual problems
Some children or infants have visual disorders that are secondary to serious diseases in their brain or nervous system. These children need the attention of a pediatric ophthalmologist who specializes in visual problems related to brain disorders. Damage to the visual pathways or occipital cortex may result in cortical blindness, optic nerve hypoplasia, and optic nerve atrophy.
Pediatricians refer infants to Bascom Palmer’s pediatric ophthalmology clinic, usually after parents notice that their babies are not developing eye fixation. Children with brain tumors may also be referred in order to obtain baseline visual examinations. When a child’s visual disorder is not obvious, diagnosis is difficult at best, depending less on diagnostic equipment than on the ophthalmologist’s interpretation of every small finding during an examination.