Normally, the eyes work as a team, aiming at the same spot, providing the brain with information to create a three dimensional image. This image provides a person with depth perception. Strabismus means that the eyes point in different directions and are not working together.
Strabismus can begin in infancy, early childhood, or even in adulthood. When strabismus begins in children before 6 years old, double vision rarely occurs because the brain is still able to shut off (or suppress) the vision in the deviating eye. When it begins at a later age, double vision is the rule if vision has developed normally.
Although the word strabismus most often brings to mind crossed eyes (esotropia), it also means any misalignment and includes walleyes (outward turning or exotropia) and one eye turning up or down (hypertropia or hypotropia).
Strabismus in children
In young children, the two most common types of strabismus are accommodative esotropia, where the eyes cross due to excessive farsightedness, and infantile esotropia, where children are born with the tendency to cross their eyes. Strabismus in children is less commonly caused by head trauma and diseases that affect the brain or nerves that go to the eye, such as tumors, hydrocephalus (water on the brain), or cerebral palsy.
In any childhood strabismus, amblyopia may occur. Often called lazy eye, amblyopia occurs when the brain shuts off the image in one eye long enough that the vision is permanently degraded in that eye. In most cases, this condition is easily resolved.
Strabismus in adults
In adults, strabismus usually causes double vision. Head trauma and diseases that affect the nerves, such as multiple sclerosis, may cause it. Long-standing high blood pressure or diabetes can cause paralysis of eye movement muscles, as can an aneurysm in blood vessels supplying the brain or a tumor.
Treatment of strabismus
Different forms of strabismus must be dealt with differently. In many cases, the solution is as easy as wearing glasses to correct farsightedness and allow the eyes to focus correctly. Accommodative esotropia is generally treated in this manner.
Infantile esotropia, on the other hand, is usually caused by problems within the muscles that move the eye. These muscles must be operated upon to align the eyes. Oftentimes, in cases of infantile esotropia when amblyopia (lazy eye) is also involved, the child must first wear a patch over the good eye to force the weaker one to develop its vision. This must be done with care because patching, if over-done, can damage vision in the good eye. Once the amblyopia is solved, surgery can be performed to straighten the eyes.
Other treatments for strabismus include eye exercises and injection of a drug called Botox into the eye muscles. An injection of Botox into an eye muscle temporarily relaxes the muscle, allowing the opposite muscle to tighten and straighten the eye. Although the effects of the drug wear off after several weeks, the misalignment may be permanently corrected in some cases.
Early detection is key
In all strabismus, early diagnosis by an eye muscle disease specialist will allow proper treatment. Timely treatment by a trained physician offers the best chance of getting the eyes working together.