What is Strabismus?
Normally, the eyes work as a team, aiming at the same spot, providing the brain with the information it needs to create a three dimensional image. This three dimensional image provides a person with depth perception. Strabismus means that the two eyes point in different directions from each other. This means the eyes are not working together and each sees a different picture, rather than one fused image, as is normal. 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 2 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 is 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 by simply patching the stronger, more developed eye and forcing the weaker eye to develop better sight. Patching must be done carefully and according to the doctor’s specifications to avoid possible damage to the stronger eye.
Strabismus in Adults
In adults, new strabismus usually causes double vision. Head trauma and diseases which 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. Often times, in cases of infantile esotropia when amblyopia (lazy eye) is also involved, the child must first wear a patch over their good eye in order to force the weaker eye to develop its vision. 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.
How is Strabismus Surgery Done?
The ophthalmologist makes a small incision in the tissue covering the eye to reach the eye muscles. Certain muscles are repositioned during the surgery. Recovery time is rapid. People are usually able to resume their normal activities within a few days. After surgery, glasses or prisms may be useful. In many cases, further surgery may be needed at a later stage to keep the eyes straight. As with any surgery, eye muscle surgery has certain risks. These include infection, bleeding, excessive scarring, and other rare complications that can lead to loss of vision. Strabismus surgery is usually a safe and effective treatment for eye misalignment. It is not, however, a substitute for glasses or amblyopia therapy.
Early Detection is Key
In all strabismus, early diagnosis by a specialist in eye muscle disease will allow proper treatment as quickly as possible. Timely treatment by a trained physician offers the best chance of getting the eyes working together. Amblyopia is a condition of the eye, often related or secondary to strabismus.