Eye Misalignment (Strabismus)Strabismus refers to misaligned eyes. If the eyes turn inward (crossed), it is called esotropia. If the eyes turn outward, it is called exotropia. Or, one eye can be higher than the other which is called hypertropia (for the higher eye) or hypotropia (for the lower eye). Strabismus can be subtle or obvious, intermittent (occurring occasionally), or constant. It can affect one eye only or shift between the eyes.
Strabismus usually begins in infancy or childhood. Some toddlers have accommodative esotropia. Their eyes cross because they need glasses for farsightedness. But most cases of strabismus do not have a well-understood cause. It seems to develop because of a poor ability of the brain to use the eyes together, allowing them to drift. Acquired strabismus can occasionally occur because of a problem in the brain, an injury to the eye socket, or thyroid eye disease.
When young children develop strabismus, they typically have mild symptoms. They may tilt or turn their head if they can use their eyes together in that position. Or, they may close or cover one eye when it deviates, especially at first. Adults, on the other hand, have more symptoms when they develop strabismus. They can have double vision (see a second image) and may lose depth perception. At all ages, strabismus is disturbing. Studies show school children with significant strabismus have self-image problems.
Amblyopia, or lazy eye, is closely related to strabismus. Children learn to suppress double vision so effectively that the deviating eye gradually loses vision. It may be necessary to patch the good eye and wear glasses before treating the strabismus. Amblyopia does not occur when alternate eyes deviate, and adults do not develop amblyopia.
Strabismus is often treated by surgically adjusting the tension on the eye muscles. The goal of surgery is to get the eyes straight enough that the brain can develop some depth perception. Many children will develop the ability to use the eyes together following surgery. Many adults who have had strabismus for many years may also develop some ability to use the eyes together. Surgery is performed under general anesthesia. The muscle alignment can often be adjusted in adults following surgery.
Please ask Dr. Nichols if you have additional questions regarding strabismus. In addition, Children’s Eye Foundation has an excellent comprehensive guide to strabismus surgery for parents and patients.