What Is Strabismus?

Strabismus is the medical term for misalignment of the eyes. In strabismus, the eyes can be not work together because the eyes are turning in (“crossed eyes” or esotropia), out (exotropia), up, or down abnormally.

Approximately four percent of children in the United States are affected by strabismus. Adults can also have strabismus causing double vision. Strabismus is common after thryoid-related eye disease (such as Graves ophthalmopathy and hypothyroidsm). 

There are various reasons for this condition, ranging from a need for glasses to ocular (eye) or neurological abnormalities. A parent or close relative is often the first to notice a vision problem.

When a vision problem is suspected, a complete eye examination should be arranged as soon as possible. Early detection and management are important for best results. 

How Is Strabismus Managed?

The Duke Pediatric Eye team includes pediatric ophthalmologists, orthoptists, and technicians. Orthoptists specialize in identifying eye muscle imbalances and examining children with eye problems. They assess visual acuity in infants and children, measure ocular deviations, and evaluate eye movements.

The level of the examination will be adapted to your child’s ability to respond. We obtain much useful information through observation of your child’s visual behavior.

Although responses are helpful, verbal ability is not necessary to complete an accurate eye examination. 

What Is Amblyopia?

When a young child uses one eye predominately and does not alternate between the two eyes, the prolonged suppression of the non-dominant eye by the brain may develop into amblyopia.

Amblyopia is sometimes referred to as “lazy eye,” but it is more than just an eye problem. The visual portion of the brain is suppressed and vision actually decreases in the unused eye.

There are different causes of amblyopia:

• Strabismus -- misalignment of the eyes causing one eye to not be used properly
• Refractive error -- a child who is very near sighted or far sighted and needs glasses to improve vision can have difficulty developing the connections needed to achieve good vision
• The presence of a cataract (an opacity of the lens inside the eye) that distorts light images from properly focusing on the back of the eye, preventing good vision from developing for that eye
• A droopy or enlarged eyelid that covers the pupil and blocks the vision in that eye

In some cases there may be more than one cause.

How Is Amblyopia Treated?

Amblyopia (“lazy eye”) is by far the greatest cause of treatable vision loss in the United States. A child with amblyopia may lose vision in the affected eye permanently if the situation is not corrected early. Treatment is more difficult and less effective with children older than nine or 10 years of age.

If your child is diagnosed with amblyopia, an individual active treatment program will be designed. This program may involve one or more of the following: eyeglasses, patch therapy, eye drops that dilate the pupil, and, in some cases, a contact lens.

Your ophthalmologist and orthoptist will give you specific information about the treatment for your child. 

Eye Muscle Surgery (Strabismus Surgery)

Many patients with eye deviations will eventually need an operation to align the eyes. The goals of surgery are twofold. The first is to change the present eye alignment in such a way as to enable the brain to use both eyes together. This may reestablish binocular function. The second is to improve the appearance so that the eyes look straight and move together.

The chances for achieving these goals are influenced by the size and complexity of the eye deviation, the age of onset, types of previous treatment, quality of binocular function (depth perception), and the compliance with pre- and postoperative therapy.

The results of strabismus surgery are not always perfect because human tissue varies from individual to individual. Therefore, it may take more than one operation to achieve the goal of straight eyes. The success rate varies from 50 to 90 percent, depending on the type of operation and condition of the eyes.

In some cases the surgery may be performed in steps, with the first operation designed to correct only part of the problem. A second or even third operation may be necessary to deal with any residual misalignment or to correct another aspect of the problem. The purpose of this discussion is to acquaint you with the facts about strabismus surgery. With vigorous and complete treatment the results are usually extremely gratifying.

For strabismus, amblyopia (lazy eye), and related eye muscle disorder treatments, visit a Duke Eye Center near you in Durham, Raleigh, Cary, and other areas of North Carolina.