The exact cause of strabismus is not fully understood. Six eye muscles, controlling eye movement, are attached to the outside of each eye. In each eye, one muscle moves the eye to the right, one-muscle moves the eye to the left. The other four muscles move it up or down and at an angle.
To line up and focus both eyes on a single target, all of the muscles in each eye must be balanced and working together. In order for the eyes to move together, the muscles in both eyes must be coordinated. The brain controls these eye muscles.
Strabismus is especially common among children with disorders that may affect the brain, such as :
- Cerebral palsy
- Down syndrome
- Hydrocephalus
- Brain tumors
- Premature birth
However local causes around the eye can also cause squint, although less frequently.