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What is strabismus?

Strabismus is one of the most common eye conditions in children, affecting between 2 and 4 percent of the population. Strabismus occurs when the eyes are not aligned properly. One or both of your child’s eyes may turn inward (esotropia), outward (exotropia), upward (hypertropia), or downward (hypotropia).

Your child can be born with strabismus, or it can be acquired later in life. Strabismus can also develop as the result of an accident or other health problem. In some children, strabismus is intermittent, while in others it is always present.

Early diagnosis is essential in preventing vision loss that occurs as a result of amblyopia, also called “lazy eye.” Amblyopia from strabismus occurs when vision does not develop normally during childhood because the eyes are not aligned.

What are the complications of strabismus?

  • amblyopia occurs in up to one-half of younger children
  • diplopia (double vision) can occur in acquired strabismus in older children and adults
  • problems in socializing or working resulting from the appearance and function of the eyes

Strabismus and Amblyopia | Symptoms & Causes

What are the symptoms of strabismus?

Babies and children with strabismus should be checked right away to prevent amblyopia, which results in loss of vision and depth perception, due to the misaligned eye. Amblyopia can occur even if the eye is only slightly misaligned because a developing child's brain will stop communicating with that eye, shutting it off.

Unfortunately, it isn't always easy for parents to tell if a child's eyes are misaligned, particularly in those children with a mild case of strabismus. If your child is showing any of the following signs and symptoms of strabismus, schedule an appointment for an eye exam with an ophthalmologist:

  • during the first three months of life, the eyes are wandering outward all the time or the eyes are crossed inward
  • after 3 months of age, one or both of eyes is wandering out or crossing in
  • tilting of the head in order to effectively line up the eyes to use them together or squinting one eye, especially in bright sunlight, to block out a double image resulting from the misaligned eyes pointing in different directions
  • red eye reflection in one eye
  • when a sibling has strabismus

What causes strabismus?

Experts don’t completely understand the cause of strabismus, but it results from the failure of the eye muscles to work together. Idiopathic (resulting from an unknown cause) strabismus is the most common type. Other conditions can also cause strabismus:

  • Duane syndrome
  • Moebius syndrome
  • thyroid eye disease
  • nerve damage
  • cerebral injuries
  • fracture of the orbital wall

Risk factors for strabismus may include the following:

  • family history of strabismus
  • prematurity or low birth weight
  • retinopathy of prematurity
  • conditions that affect vision, such as cataracts, severe ptosis, and corneal scars
  • muscular abnormalities
  • neurological abnormalities
  • amblyopia

Strabismus and Amblyopia | Diagnosis & Treatments

How is strabismus diagnosed?

Strabismus is diagnosed during an eye examination. Evaluation of the eyes and vision should be performed in the pediatrician's office at every well-child visit. But if your child is having symptoms of strabismus or other eye disorders at any age, a complete eye examination by an ophthalmologist should be performed.

What tests are used to diagnose strabismus?

There are a variety of tests that can help detect strabismus and associated amblyopia. Light reflex testing evaluates the alignment of the eyes by having your child look directly at a point of light. Another test uses prisms to analyze whether your child’s eyes are properly aligned. If your child is not yet able to talk, vision can be assessed by evaluating your child’s ability to fixate on a moving object or your child’s response when one of the eyes is covered. If your child is older, a standard eye chart with either letters or pictures will be used to test vision.

Your child’s doctor will also ask you about your family history and how and when your child’s strabismus appeared. To provide the most effective care, it is important to determine whether your child was born with strabismus or acquired it as the result of another health problem.

What are the treatment options for strabismus?

If strabismus is treated early, your child will have a better chance to use his or her eyes together to develop binocular vision and depth perception. It's also important to treat strabismus soon after diagnosis to avoid the onset of amblyopia, which can result in permanent vision loss.

Mild strabismus

  • Glasses: Your child's eye doctor may prescribe glasses to correct the alignment problem.
  • Patching: Sometimes your doctor may recommend placing a patch over the normally functioning eye for a number of hours every day. "Patching" can help remind the brain that it needs to pay attention to both eyes, which sometimes can improve the alignment.

Severe strabismus

  • Eye muscle surgery is typically needed to straighten the eyes and prevent vision loss when other interventions don't work.
  • The surgery involves detaching the muscle or muscles that is causing misalignment and reattaching it or them to a new spot.

Botox injections

Very few places in the New England region and in the country offer Botox (botulinum toxin A) injections as an option for treatment in children with strabismus. At Boston Children's, eye doctors can occasionally use Botox instead of eye muscle surgery to correct strabismus.

Sometimes, this method proves effective in children for whom surgery has not corrected the misalignment. For adults and older children, this treatment can be given in the office. For young children, the procedure is performed in the operating room with a brief anesthesia but without need for incisional muscle surgery.

Adjustable sutures in eye muscle surgery

Adjustable sutures allow our ophthalmologists to readjust the position of your child's eye in the recovery room to avoid the need to schedule additional surgery. It may be hard to believe that a child would sit still for the adjustment of adjustable sutures, but our surgical and anesthesia teams perform these adjustments routinely and know how to help a child stay calm and cooperative throughout the process.

If a child is too young or too fearful to cooperate for adjustment, the procedure can be completed with a brief secondary anesthetic in the recovery room without needing to return for surgery.

How we care for strabismus

The Pediatric Strabismus Service at Boston Children's Hospital offer comprehensive evaluation and correction of strabismus in babies, children, and adults of all ages. Our highly experienced pediatric ophthalmologists are known locally and nationally for handling the most difficult cases of strabismus.

Many children and adults with complex strabismus that involves multiple eye muscles are routinely referred to Boston Children's. Here, we use baby- and child-friendly eye exams to detect strabismus, and our physicians adopt innovative approaches to straighten your child’s eyes. Adults with strabismus are referred to our pediatric practice because ophthalmologists specially trained in childhood eye conditions have expertise in the delicate eye muscle surgery typically required to straighten the eyes.

What is the long-term outlook for a child with strabismus?

It depends upon the underlying cause of your child’s strabismus, but what is true in all cases is that the sooner the condition is diagnosed, the more effective the treatment will be.

Strabismus and Amblyopia | Programs & Services