Strabismus

Topic Overview

What is strabismus?

Strabismus (say "struh-BIZ-mus") is a vision problem in which both eyes do not look at the same point at the same time. Strabismus most often begins in early childhood. It is sometimes called crossed-eyes, walleye, or squint.

What causes strabismus?

Childhood strabismus often has no known cause, although it tends to run in families.

Normally, the muscles surrounding each eye work together to move both eyes in the same direction at the same time. Strabismus occurs when the eye muscles do not work properly to control eye movement. When the eye muscles do not work correctly, the eyes may become misaligned, and the brain may not be able to merge the two images.

Sometimes strabismus develops when the eyes compensate for other vision problems, such as farsightedness.

Adults may develop strabismus from eye or blood vessel damage. Loss of vision, an eye or brain tumor, Graves' disease, stroke, and various muscle and nerve disorders can also cause strabismus in an adult.

What are the symptoms?

The most common visible sign of strabismus is when a child's eyes do not look at the same point in space at the same time. Squinting, closing one eye in bright sunlight, and tilting or turning the head to look at an object are also possible signs of strabismus.

A child with strabismus may also complain about blurred vision, tired eyes, and sensitivity to light. Double vision often occurs when strabismus first develops.

How is strabismus diagnosed?

A doctor can often tell that a child has strabismus just by looking at his or her eyes. It may be obvious that the eyes do not look in the same direction at the same time.

The doctor may have the child look at an object while covering and then uncovering each eye. This allows the doctor to determine which eye turns, how much it turns, and under what circumstances the abnormal turn occurs. These tests will also help the doctor determine whether the child has amblyopia, an eye condition also known as lazy eye in which one eye is not used enough for the visual system in the brain to develop properly.

See a picture of strabismus .

How is it treated?

The most common treatments for strabismus are the use of glasses, patches, medicines, and surgery. Wearing glasses can sometimes correct strabismus when the eyes are only slightly misaligned. Using an eye patch and medicines may improve amblyopia. Resolving amblyopia may help the eyes to align because they would be used equally, allowing them both to focus on one object. In some cases, eye exercises may be helpful.

Surgery is often the only way to correct severe strabismus. During surgery, the doctor changes the length or position of the muscles around the eye to help it align better.

Will your child outgrow strabismus?

A child rarely outgrows strabismus once it has developed. Without treatment, strabismus can cause permanent vision problems. For example, if the child is not using one eye because it is misaligned, he or she can develop poor vision in that eye (called lazy eye or amblyopia).

A newborn's eyes may initially be misaligned, but the eyes should become aligned by 3 to 4 months of age. In some cases, the eyes may simply seem to be misaligned because the child has a wide bridge of the nose that creates the appearance of crossed eyes (pseudostrabismus).

Any child older than 4 months whose eyes are not aligned all of the time should have an eye exam by an ophthalmologist. This exam should be done sooner if there is an obvious problem.

What can increase your child's risk of strabismus?

Risk factors for childhood strabismus include:

• A family history of strabismus.
• Vision problems, such as farsightedness.
• Muscle and nerve disorders (such as multiple sclerosis, myasthenia gravis, or cerebral palsy).
• Down syndrome.
• Cataract.
• Tumor in the brain or eye.
• Premature birth, low birth weight, birth injury, or newborn problems.
• Head injury.
• Infections, such as meningitis or measles.

Frequently Asked Questions

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	Amblyopia: Wearing an eye patch

Symptoms

You can sometimes see that a child has strabismus just by looking at his or her eyes. The most common visible signs are:

• Eyes that do not look in the same direction at the same time.
• Eyes that do not move together. (The direction that the affected eye moves depends on the type of strabismus the child has.)
• Squinting or closing one eye in bright sunlight.
• Tilting or turning the head to look at an object.
• Bumping into things (strabismus limits depth perception).

The child may also complain about:

• Blurred vision.
• Tired eyes.
• Sensitivity to light.
• Double vision (usually only when strabismus first develops).

If your child's eyes are only slightly misaligned, you may not be able to see that he or she has strabismus. Symptoms may come and go, and they may get worse when your child is tired or sick. If your child's eyes are not aligned all of the time after age 4 months, take your child to the doctor for an eye exam. This exam should be done sooner if you notice an obvious problem or if it is recommended by your doctor or another health professional. Your health professional may refer you to an ophthalmologist.

Even if you do not notice a problem, most doctors recommend eye exams for children before they start school.

A person who develops strabismus after age 7 to 10 years usually has double vision. If double vision develops and does not go away, an eye exam is needed. The doctor will also need to make sure that there is not a serious illness. Double vision that develops suddenly is a medical emergency.

Adults may experience sudden double vision as a result of multiple sclerosis (MS), a stroke, high blood pressure, or diabetes. If you experience double vision along with one of these conditions, see your doctor. You may need more urgent treatment.

Exams and Tests

Exams to check for strabismus are done by an ophthalmologist or, in some cases, by an optometrist. The doctor can often tell that a child has strabismus just by looking at the child's eyes. It may be obvious that the eyes do not look in the same direction at the same time.

In an exam for strabismus, the doctor determines:

• Which eye is affected (or if both are affected).
• Which way the eye turns (in, out, up, or in some cases, rotating).
• How much the eye turns.
• When the abnormal turn occurs (all of the time or only when the child looks in a certain direction).
• Whether the child always uses the same eye to focus or switches back and forth, using one eye or the other.

The doctor may ask whether you have noticed the child squinting or closing one eye, tilting or turning his or her head, or bumping into things.

Some tests may also help the doctor decide whether the child has amblyopia, an eye condition also known as lazy eye in which one eye is not used enough for the visual system in the brain to develop properly. If strabismus occurs only some of the time, or if the child switches from one eye to the other for focusing, amblyopia is less likely to develop. Finding and treating amblyopia that results from strabismus early in life can prevent permanent vision loss. For more information, see the topic Amblyopia.

Early Detection

The U.S. Preventive Screening Task Force recommends screening to detect amblyopia, strabismus, and other vision problems in children younger than age 5 years.¹

No infant is too young for an eye exam by an ophthalmologist, and an exam should be performed whenever you have questions about the health of your child's eyes. The American Academy of Ophthalmology recommends that all infants should be screened by 6 months of age by a pediatrician, a family doctor, or an ophthalmologist.

Eye exams for children and infants

Treatment Overview

Treatment for strabismus should begin as soon after diagnosis as possible. In general, the younger the child is when treatment for strabismus begins, the better the chances are of correcting the problem.

Treatment should also address amblyopia (lazy eye) or other vision problems to help normal vision to develop. If amblyopia has developed, aligning the eyes will not reverse it.

Early treatment is important to correct strabismus, but time is even more critical with amblyopia. Amblyopia can damage a child's vision quickly and permanently. After about age 7 to 10 years, no treatment can completely correct poor vision caused by amblyopia. For more information, see the topic Amblyopia.

Treatment for strabismus may include glasses, patches, drug treatments, eye exercises, botulinum toxin, or surgery.

Glasses

If the eyes are only slightly misaligned, wearing glasses can sometimes correct strabismus. Some children may need to wear bifocals or special lenses called prisms. Along with wearing glasses, they may need to use eyedrops for a while.

Eye patches

This is primarily a treatment for amblyopia (lazy eye), which may be either the result of strabismus or its cause. The stronger eye is covered with a patch to force the child to use the weaker eye. It is important to carefully follow instructions for wearing an eye patch and to not have a child wear a patch longer than your doctor recommends because excessive use of a patch can cause amblyopia in the initially stronger eye. For more information on wearing an eye patch, see:

Amblyopia: Wearing an eye patch.

Drug treatments

The doctor may prescribe certain drugs, usually in the form of eyedrops , as part of the treatment. Atropine and miotics (such as echothiophate iodide) affect muscles in the eye that control the pupil and the eye's ability to focus. Miotics may be used when strabismus is caused by problems in focusing the eyes. Atropine is sometimes used as an alternative to patching to help treat poor vision (amblyopia) in one eye by blurring the vision in the good eye beyond that of the weaker eye and forcing the child to use the weaker eye.

Eye exercises

Exercises may occasionally be used in addition to other treatments, such as surgery. But eye exercises alone are not helpful in most cases of strabismus.

Botulinum toxin

Botulinum toxin (such as Botox) is a drug that temporarily prevents contraction of a muscle for several months at a time. This causes the muscle to relax, which allows the opposing muscle to change the eye's position. It is sometimes used as a supplemental treatment when surgery does not entirely correct the misalignment of the eyes. It is a controversial treatment, however, because it may require many injections, results are not always predictable, and it may create other vision problems and simply delay further surgery.

Surgery

Surgery is often the only way to align the eyes and improve vision in children who have strabismus. During surgery, the doctor loosens or tightens the muscles around the eye by changing their length or position. Altering the pull of the muscles can bring the eyes back into line with each other. A child may need more than one surgery to realign the eyes and improve vision and may have to wear or continue wearing glasses after the surgery.

Because early treatment is important to correct strabismus, surgery in children younger than age 2 is not unusual, and it can be performed as early as 3 months of age in serious cases, particularly if the strabismus is detected early. But the effectiveness of surgery in children younger than 6 months is controversial because, although rare, strabismus in very young children sometimes disappears on its own as development continues.²

Surgery in adults to correct strabismus, although not as common as in children, is a safe and effective way to improve alignment of the eyes. Surgery in an adult can improve vision and depth perception, relieve double vision, broaden the visual field when the eyes are turned inward, or reduce the visual field when eyes are turned outward. Having surgery can also improve self-esteem and the ability to communicate with others.³

See a picture of how strabismus is corrected with surgery .

Home Treatment

If your child's treatment for strabismus includes wearing glasses or a patch, make sure that your child wears them exactly as directed. It is very important that patches are used exactly as instructed by your doctor, because wearing a patch for too short a time can make the treatment less effective, and wearing it for too long can cause problems in the stronger eye.

If your child has to wear special contact lenses to treat amblyopia (lazy eye), you will need to learn how to put them in and take them out. Be sure your child uses any eyedrops that the doctor prescribes exactly as directed.

Having strabismus can be hard on your child's self-esteem. In addition to affecting the child's ability to see well, strabismus affects the child's appearance. Other kids may tease your child for being cross-eyed or having a walleye. Be supportive of your child, and seek treatment right away. In addition to helping improve vision, treatment to align the eyes can improve the child's appearance and self-esteem.

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Organizations

Related Information

• Amblyopia
• Eye Problems, Noninjury
• Nearsightedness (Myopia)

References

Citations

1. U.S. Preventive Services Task Force (2004). Screening for visual impairment in children younger than age 5 years: Recommendation statement. Rockville, MD: Agency for Healthcare Research and Quality. Available online: http://www.ahrq.gov/clinic/uspstf/uspsvsch.htm.

2. Wright KW (2003). Common types of strabismus. In Pediatric Ophthalmology for Primary Care, pp. 47-70. Denver: American Academy of Pediatrics.

3. Mills MD, et al. (2004). Strabismus surgery for adults: A report by the American Academy of Ophthalmology. Ophthalmology, 111(6): 1255-1262.

Other Works Consulted

• Tsai LM, Kamenetzky SA (2006). Strabismus section of The eye and ocular adnexa. In GM Doherty, LW Way, eds., Current Surgical Diagnosis and Treatment, 12th ed., p. 986. New York: McGraw-Hill.

• Chatzistefanou KI, Mills MD (2000). The role of drug treatment in children with strabismus and amblyopia. Pediatric Drugs, 2(2): 91-100.

• Fredrick DR, Asbury T (2004). Strabismus. In P Riordan-Eva, JP Whitcher, eds., General Ophthalmology, 16th ed., pp. 230-249. New York: Lange Medical Books/McGraw-Hill.

• Madan A, Good WV (2005). Epidemiology of vision impairment in children section of Disorders of the eye. In HW Taeusch et al., eds., Avery's Diseases of the Newborn, 8th ed., chap. 101, pp. 1546-1548. Philadelphia: Saunders.

• Mills MD, Khazaeni LM (2006). Strabismus. In FD Burg et al., eds., Current Pediatric Therapy, 18th ed., pp. 1096-1098. Philadelphia: Saunders.

• Sands R, et al. (2005). Amblyopia and strabismus section of Eye. In WW Hay et al., eds., Current Pediatric Diagnosis and Treatment, 17th ed., pp. 457-461. New York: McGraw-Hill.

• Trobe JD (2001). Strabismus. In Physician's Guide to Eye Care, 2nd ed., pp. 181-183. San Francisco: American Academy of Family Physicians.

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