What is strabismus?
The natural eye position is to be aligned in the same direction. Strabismus is the medical term for any eye misalignment. It is estimated that 4% of the US population has strabismus. Strabismus is more common in children but also occurs in adults.
Strabismus is described by the direction of the misaligned eye:
- Inward crossing (esotropia)
- Outward (exotropia)
- Upward (hypertropia)
- Downward (hypotropia)
Esotropia (inward crossing) is the most common horizontal strabismus in children and can be divided into many different types of esotropia. The two most common occurring in childhood include:
- Infantile esotropia: Onset occurs by 6 months of age with a large amount of crossing and is constant.
- Accommodative esotropia: Onset occurs later, around 2-3 years old, and is due to high far-sightedness (hyperopia). This type of crossing is usually treated with glasses.
Exotropia is a horizontal strabismus occurring when the eyes are misaligned outward. Onset typically occurs after 6 months of age and can be constant or intermittent (come and go). Infantile exotropia onset starts before 6 months of age and is not as common.
What is Lazy Eye?
Lazy eye is a non-specific, non-medical description many people use to describe any problem with a child’s eyes or vision development. It is commonly used to describe strabismus (misalignment), amblyopia (poor vision), or ptosis (droopy eyelid).
What are the symptoms of strabismus?
Of course the most common and noticeable symptom is ocular misalignment. Other symptoms are more frequent in older children. These signs and symptoms can include:
- Blurry vision
- Eye strain
- Head tilt or abnormal head position
- Double vision
- Abnormal 3-D vision
What causes strabismus?
Strabismus is most commonly caused by a problem with the brain control of eye alignment and movement. Less commonly it is a problem with the muscle or eye itself. It is not completely understood, however there is a genetic component and can run in families. It is not uncommon for parents to initially believe there is no family history, only to learn about a relative who had strabismus as a child that was successfully treated. Sometimes the treatment is so successful that no one remembers they had strabismus.
Other causes include:
- Refractive error (near-sighted, far-sighted, astigmatism)
- Amblyopia (poor vision development)
- Retinopathy of prematurity
- Medical conditions associated with strabismus
- Genetic medical conditions associated with strabismus
- Many others
Can adults have strabismus?
Yes, adults can have strabismus. It can be a worsening or progression of eye misalignment from childhood or it can be a new medical issue starting in adulthood. When strabismus starts in childhood, there is often no associated double vision (diplopia) in adulthood. However strabismus that starts in adulthood after the visual system has developed (adult onset strabismus) is often associated with double vision. Adult onset strabismus often requires a medical evaluation for the cause such as blood tests or neuroimaging (MRI or CT scan of the brain). Adult onset strabismus can be caused by trauma, thyroid dysfunction, diabetes, stroke, tumor, neurologic changes, and many other medical conditions. Sometimes a cause cannot be identified.
How is strabismus treated?
An ophthalmologist specially trained in this condition will determine the appropriate treatment plan based on the type and cause of the misalignment. Not all strabismus is the same so they are not all treated the same. What works for one patient does not work for another, even within the same family.
Treatment options may include a combination of the following:
- Eye patching
- Treatment of underlying disease or medical problem
In all cases, close monitoring of vision development in childhood is vital in children with strabismus to insure continued vision development.