An estimated 4 percent of the U.S. population has the condition, which usually develops by age 3. Older children and adults can develop the condition as well.
Causes and Risk Factors of Strabismus
Strabismus can be a result of problems with your eye muscles, the nerves that transmit signals to the muscles, or the brain’s control center that directs eye movements. It can also be caused by eye injuries or general issues with your health.
Risk factors for developing strabismus include:
- Family history
- Uncorrected farsightedness
- Medical conditions, such as Down syndrome, cerebral palsy, hydrocephalus, brain tumor, diabetes, or thyroid disorders
- Head injury
- Intermittent exotropia This is caused by an inability to coordinate both eyes, resulting in the eye or eyes pointing beyond the object being viewed. It can lead to eyestrain, difficulty reading, headaches, and difficulty with vision in bright sunlight.
- Accommodative esotropia This is due to uncorrected farsightedness. The extra strain needed to keep eyes focused may cause the eyes to turn inward.
- Cerebral palsy
- Congenital rubella
- Noonan syndrome
- Traumatic brain injury
Strabismus may develop in adults due to:
- Eye disease or injury
- Graves' disease
- Guillain-Barré syndrome
- Shellfish poisoning
- Traumatic brain injury
How Is Strabismus Diagnosed?
An optometrist or ophthalmologist — two types of eye doctors — should evaluate any child older than 4 months whose eyes don’t appear to be in sync all the time.
Given that a family history of strabismus is a risk factor for the condition, the exam should start with a detailed patient history, during which the doctor will ask about current symptoms and any other health problems, medications, or environmental factors that may be contributing to them.
They will also ask if anyone in your family has been diagnosed with strabismus.
An eye doctor or pediatrician can diagnose strabismus simply by looking at the eyes. There are also a few tests that can confirm the diagnosis.
In addition to assessing visual acuity — how well your eyes can see — using a Snellen eye chart, your doctor will evaluate how well your eyes focus, move, and work together.
In children able to communicate and cooperate — as well as in adults — both intermittent and constant strabismus can be diagnosed with the “cover-uncover” or “alternating cover” tests.
In these tests, you or your child will be asked to stare at an object. Your doctor will observe the response of each of the eyes when the other is covered and uncovered.
Prognosis of Strabismus
In most cases, strabismus can be corrected if it’s identified and treated early.
Permanent vision loss in one eye — a condition called amblyopia (or “lazy eye”) — can result if treatment is delayed. About one in three children with strabismus will develop amblyopia.
Treatment and Medication Options for Strabismus
Treatments for strabismus include:
- Eyeglasses or contact lenses
- Patching the stronger eye
- Prism lenses
- Vision therapy
Currently, there are no prescription medications approved by the U.S. Food and Drug Administration (FDA) for the treatment of strabismus.
In some cases, special eyeglasses or contact lenses can be used to treat strabismus. These vision products are designed to get the eyes to work — and move — together.
Many adults with mild, intermittent strabismus find that eyeglasses can correct the problem.
Prism lenses change the light entering the eye and help reduce the amount of turning the eye has to do to focus.
Vision therapy is a series of eye exercises designed to improve coordination and the eyes’ ability to focus.
You or your child may need strabismus surgery if the eyes still don’t move correctly. Strabismus surgery is generally an outpatient procedure that’s performed while the patient is under general anesthesia.
An ophthalmologic surgeon can better align a person’s eyes by altering the length or position of the eye muscles. The surgeon will either loosen or tighten the eye muscles, making them stronger or weaker, to correct the alignment of the eyes.
In some cases, an adjustable suture is used to correct the eyes’ alignment after the surgery is complete.
Eye strabismus surgery doesn’t fix lazy eye. As a result, you may need to use an eye patch and antibiotic eye drops (with or without corticosteroids) as well as vision therapy following the surgery.
Prevention of Strabismus
Strabismus can’t be prevented, but the complications of the condition — including amblyopia — can be if they’re diagnosed and treated early.
Research and Statistics: How Many People Have Strabismus?
Resources We Love
American Association for Pediatric Ophthalmology and Strabismus
This organization provides you with the latest information on pediatric eye health, including issues related to strabismus. The site can also help you find a pediatric ophthalmologist in your area.
Boston Children’s Hospital: Adults With Strabismus Service
Boston Children’s is one of the leading pediatric hospitals in the United States. In addition to treating young people with strabismus, it has a dedicated program for adults with the condition.
Wilmer Eye Institute at Johns Hopkins University
Another leading eye care center, Wilmer Eye Institute is home to some of the top research minds in the country. In addition to being an excellent source for the latest on eye issues, including strabismus, the institute treats all vision conditions.
American Academy of Ophthalmology
An excellent source for the latest on eye health, this organization can connect you with free or low-cost vision-care services.
Additional reporting by Anne L. Fritz.
Editorial Sources and Fact-Checking
- Strabismus (Crossed Eyes). American Optometric Association.
- Strabismus. American Association for Pediatric Ophthalmology and Strabismus. October 7, 2020.
- Strabismus: Testing and Diagnosis. Boston Children’s Hospital.
- Strabismus Measurements. American Association for Pediatric Ophthalmology and Strabismus. March 2019.
- Strabismus. MedlinePlus. August 28, 2018.
- Crossed Eyes (Strabismus). Harvard Medical School. December 2018.
- Strabismus and Amblyopia. Boston Children’s Hospital.
- Friedman DS, et al. Prevalence of Amblyopia and Strabismus in White and African American Children Aged 6 Through 71 Months: The Baltimore Pediatric Eye Disease Study. Ophthalmology. November 2009.
- Martinez-Thompson JM, et al. Incidence, Types, and Lifetime Risk of Adult-Onset Strabismus. Ophthalmology. April 2014.