Strabismus is an eye muscle imbalance that causes one or both eyes to be out of alignment. It can occur at birth, during childhood and/or later in adulthood. Strabismus that develops in adulthood is frequently a result of an underlying vascular disease such as diabetes or high blood pressure that affects the nerves leading to the eye.
Individuals that have strabismus may experience one or both of the following:
- blurred vision
- double vision
- one eye may turn outward (exotropia)
- an eye may turn inward (esotropia)
- an eye may turn upward (hypertropia)
- Physically, their eyes appear crossed or misdirected such that the eyes do not move together as the point of focus changes.
As with any vision problem, treatment is determined after a thorough ophthalmic exam. Besides the use of a standard eye chart, the ophthalmologist may also perform tests that measure how misaligned the eyes are (prism test) and a depth perception test (stereopsis test). None of the tests are invasive or cause any discomfort.
When strabismus is detected in an infant, certain testing may not be possible. The doctor may choose to strengthen the misaligned eye(s) by placing a patch over the stronger eye so that the infant is forced to use the weaker eye. The patch may be moved to the other eye to keep a balance. Vision therapy is not an exact science. It will take sometimes years of training and retraining the eyes to keep the nerves and muscles working so that the brain does not shut them off entirely. Surgery is also an option. It is performed to strengthen or weaken muscles that control the eyes. The “cure” rates vary from 11% to 75% depending upon the surgeon’s definition of cure.
Note: It is vital to the correction of strabismus that treatment begins as early as possible. A child’s nervous system continues to develop through infancy and can only be corrected during this sensitive period. Doing nothing and waiting will only cause permanent, irreversible damage.