Strabismus is a visual defect in which the eyes are misaligned, due to eye muscle irregularities. Everyone – young and old, male and female -- can be affected. Nearly 4% of U.S. children have strabismus, and early detection can prevent further vision loss..
The precise reason for strabismus is not fully understood. One eye may look straight ahead, while the other turns in or out, up or down. The condition may be present all of the time or come and go. And the misaligned eye can even change.
With normal vision, both eyes aim at the same spot, and the brain then merges the two pictures into a single, three-dimensional image, giving us proper depth perception.
There are several types of strabismus:
Esotropia is a misalignment where the eye turns inward towards the nose.
Exotropia is a misalignment in which the eye turns outward, away from the nose.
Hypertropia is a misalignment causing an upward gaze of one eye while the other stays straight and fixates normally.
Hypotropia is a misalignment causing a downward gaze of one eye while the other eye stays straight and fixates normally.
In a child with strabismus, two different images are sent to the brain. The young brain learns to ignore the picture from the misaligned eye, and sees only the image from the straight one. This causes poor vision in the misaligned eye and hampers the ability to develop accurate depth perception.
All children should have their vision checked by their pediatrician, family doctor or ophthalmologist at or before their fourth birthday.
In some cases eyeglasses can be prescribed to strengthen the weaker eye. Covering or patching the stronger eye is often used to achieve the same goal. However, surgery may be required to realign or balance the eye muscles..