Health Encyclopedia

Strabismus

Definition

Strabismus is a disorder that causes one eye to be misaligned with the other when focusing.

Alternative Names

Crossed eyes; Esotropia; Exotropia; Squint; Walleye

Causes, incidence, and risk factors

Strabismus is caused by a lack of coordination between the eyes. As a result, the eyes look in different directions and do not focus at the same time on a single point.

In most cases of strabismus in children, the cause is unknown. In more than half of these cases, the problem is present at or shortly after birth (congenital strabismus).

In children, when the two eyes fail to focus on the same image, the brain may learn to ignore the input from one eye. If this is allowed to continue, the eye that the brain ignores will never see well. This loss of vision is called amblyopia, and it is frequently associated with strabismus.

Some other disorders associated with strabismus in children include:

Retinopathy of prematurity
Retinoblastoma
Traumatic brain injury
Hemangioma near the eye during infancy
Apert syndrome
Noonan syndrome
Prader-Willi syndrome
Trisomy 18 (a child has 3 copies of chromosome 18, instead of the normal 2 copies)
Congenital rubella
Incontinentia pigmenti syndrome
Cerebral palsy

Acquired strabismus in adults can be caused by injuries to the orbit of the eye or injuries to the brain, including closed head injuries and strokes. People with diabetes may have loss of circulation, causing a condition known as acquired paralytic strabismus. Loss of vision in one eye from any cause will usually cause the eye to gradually turn outward (exotropia). Because the brains of adults are already developed for vision, the problems associated with amblyopia do not occur with adult strabismus.

Some disorders associated with strabismus in adults include:

Diabetes
Vision loss from any eye disease or injury
Stroke
Traumatic brain injury
Paralytic shellfish poisoning (PSP)
Guillain-Barre syndrome
Botulism

A family history of strabismus is a risk factor. Farsightedness may be a contributing factor. In addition, any other disease causing vision loss may produce strabismus as a complication.

Symptoms

Eyes that appear crossed
Eyes that do not align in the same direction
Uncoordinated eye movements (eyes that do not move together)
Double vision
Vision in only one eye, with loss of depth perception (depth perception is our ability to see three dimensions, and recognize the order of objects in the space around us)

Signs and tests

Your child's health care provider will first determine if the child truly has strabismus. If the child has strabismus, a workup will be done to determine the cause.

The physical examination will include a detailed examination of the eyes. The patient may be asked to look through a series of prisms to determine the differences between the eyes. The eye muscles will be tested to determine the strength of the extraocular muscles.

Tests include:

Standard ophthalmic exam
Visual acuity
Retinal exam
Neurological examination

Treatment

Initially, strategies to strengthen the weakened muscles and thereby realign the eyes are attempted. Glasses may be prescribed. Eye muscle exercises may be prescribed.

If amblyopia is present, patching of the preferred eye may be done to force the child to use the amblyopic eye. Surgery may be required to realign the eye muscles if strengthening techniques are unsuccessful.

Expectations (prognosis)

With an early diagnosis, the defect can usually be corrected. With delayed treatment, vision loss in one eye may be permanent.

Complications

Loss of vision in one eye due to amblyopia
Embarrassment over facial appearance with eye patch

Calling your health care provider

Strabismus requires prompt medical evaluation. Call for an appointment with your health care provider or eye doctor if your child exhibits any of the following:

Complains of double vision
Has difficulty seeing
Appears to be cross-eyed
The eyes do not appear to fix on the same point

Also call if there are problems at school, which could possibly be related to the child being unable to see the blackboard or the reading material.

Review Date:8/8/2006
Reviewed By:Paul B. Griggs, MD, Department of Ophthalmology, Virginia Mason Medical Center, Seattle, WA. Review provided by VeriMed Healthcare Network.

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