Strabismus

What Is Strabismus or Crossed Eyes?

“Crossed eyes” is the common term for strabismus, a condition in which the eyes fail to align properly and instead look in different directions at the same time. This misalignment of the eyes can cause double vision, poor depth perception, and reduced vision in the turned eye. When left untreated, strabismus can lead to amblyopia (lazy eye) in which the brain ignores visual signals from the turned eye, with long-term consequences for overall vision.

Strabismus is a common childhood eye condition, affecting up to 5% of children in the United States, but may develop at any age.

What Causes Strabismus?

Eye movement is a complex interaction between the brain and the muscles and nerves associated with the eyes. Each eye has six muscles that control its movements. In addition, three cranial nerves also play a role. Abnormalities in any of these muscles or nerves, or in the connection between them and the brain, can cause strabismus.

Risk factors for developing strabismus include:

• A family history of strabismus
• Uncorrected refractive error
• Disorders that affect the brain such as Down syndrome and cerebral palsy
• Trauma
• Stroke

Common Strabismus Symptoms

The most recognizable symptom of strabismus is one eye that does not look straight ahead. It might turn in (esotropia), turn out (exotropia or “wall-eyed”), turn up (hypertropia), or turn down (hypotropia). Strabismus might be either constant or intermittent and can always involve the same eye, sometimes even alternating between eyes. Other noticeable symptoms include squinting one eye in bright light or tilting the head to one side in an attempt to align the eyes.

Sometimes infants will appear to have crossed eyes when in fact they do not. This is a condition known as pseudostrabismus. It occurs when a fold of skin covers up a portion of the corner of the eye that makes it appear as if the eye is turning in but the eyes are actually still tracking and focusing together. Children typically outgrow pseudostrabismus, but this will not be the case with true strabismus. A pediatric ophthalmologist can distinguish between the two.

How Is Strabismus Diagnosed?

For young children, strabismus is usually first detected by a parent, a pediatrician, family practitioner, or another caregiver who notices that an eye is turned. An actual diagnosis requires a comprehensive pediatric eye examination to determine with certainty if strabismus is present and to diagnose the particular type of strabismus and possible underlying causes. While older children and adults likely notice the turning of the eye themselves, they too require a comprehensive eye examination to verify a strabismus diagnosis.

Strabismus Treatments

The purpose of strabismus treatment is to straighten the eyes and enable them to work together to provide binocular vision. The specific treatment depends on the type and severity of the strabismus. Standard strabismus treatment options include:

• Prescription eyeglasses with or without prisms
• Orthoptics (eye exercises designed to restore or strengthen binocular vision)
• Botox injections
• Eye-patching therapy
• Eye muscle surgery

Strabismus Surgery

If your ophthalmologist determines that the best course of action to address the strabismus is to perform surgery on the eye muscles, here is information you should know about the procedure:

• The eyeball is not removed during surgery.
• A lid speculum is used to gently hold open the eyelids.
• The muscle is accessed via a small incision made in the membrane that covers the surface of the eye.
• The surgeon will weaken, strengthen, or move the muscle as needed.
• Dissolvable sutures are used.
• Surgery usually takes less than two hours, although it may be longer if surgery is performed on both eyes or in very complicated cases.
• Many patients require more than one surgery to maximally correct strabismus.

Patients can usually resume normal activities within a few days after surgery. However, eyeglasses may still be required after surgery.