Strabismus is an alignment problem with the two eyes. The person might be referred to as being “wall-eyed” or “cross-eyed”. They do not have binocular vision because the eyes do not focus on the same place – one is turned outward, inward, upward, or downward. It may be constant, or just at times of illness or stress.
It is thought by ophthalmologists that about five percent of children have some degree of strabismus. Contrary to a popular belief, they do not outgrow it. In the early years, it gives double vision, because the brain is still accepting image data from both eyes separately, rather than merging them into one image.
If the strabismus is constant, the brain will start to ignore data from one eye. Double vision then goes away, but the problem remains, and that ignored eye will atrophy from disuse. That is the condition known as Amblyopia, or Lazy Eye.
If the strabismus is intermittent, the brain will continue to accept information from both eyes, and this allows more time to diagnose and treat the strabismus. However, it also makes it harder to diagnose, as the parent or teacher may see it happening, but an eye doctor may not, or vice versa.
Types of Strabismus
This is also called convergence insufficiency -- one eye turns outward. It may only happen some of the time, and in a young child, this is enough for vision to develop properly with the brain learning how to balance the images from both eyes. In an older child, if the turn happens during distance vision, it is mostly a cosmetic problem although the child may appear to be inattentive. If it happens during near vision, there may be headaches, double vision, difficulty with reading, and blurry vision.
In esotropia one eye turns inward. Sometimes a new baby can appear to have this condition, but as the bridge of the nose develops, more of the eye’s sclera becomes exposed, which makes the eyes look normal. If the inward turn is constant, surgery may be done. This can improve the cosmetic appearance of the eyes but not necessarily the child’s vision. Depth perception may be lacking. Often a combination of surgery and vision therapy is more effective.
In hypertropia, one eye turns upward. It is usually a specific muscle which would normally raise or lower the eye’s direction but which is paralyzed. This can be inborn or can develop later in life. If vision therapy does not improve this condition in about six months, surgery may be necessary.
A customized program of vision therapy is usually the preferred starting point for correcting strabismus. This would be an in-office session once or twice a week lasting 30 to 60 minutes. The program is under a doctor’s care and usually supervised by an optometrist or physical therapist.
Some of the tools used in vision therapy are:
- Prescription lenses
- Eye exercises
- Optical filters and prisms
- Eye patches
- Computer software
- Balance equipment
- Training devices for integrating vision, movement and sensory information
If you or your child has strabismus it would be well to have it examined by an experienced ophthalmologist as soon as possible. To find one in your area, you can use our map of the states or our contact form.