Strabismus

Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at August 3, 2016
StartDiseasesStrabismus

Strabismus or crossed eyes as it is commonly known, is a condition in which both eyes are unable to look in the same direction simultaneously. This is often the result of weakened eye muscles, and it is experienced most commonly by children. Strabismus is not recognized as a permanent condition and prompt diagnosis and treatment can correct the problem in its entirety.

Contents

Definition and Facts

The failure for both eyes to be able to look in the same direction at the same time is usually the result of one out of six of the extraocular muscles surrounding the eye demonstrating weakness or underdevelopment, or exerting too much force or not nearly enough. With this condition, one eye tends to look straight ahead, while the other tends to point to the side, inward, upward, or downward, which also summarizes the three types of strabismus:

  • Esotropia, which is commonly misdiagnosed as a person having a lazy eye (amblyopia). This is when one of the eyes is turned inward facing the bridge of the nose.
  • Exotropia, which is an outward position of the eye that grows progressively worse over time.
  • Hypertropia, which is when the affected eye is above the other eye; hypotropia is the opposite.

Though this seems severe by definition, it is a common, highly treatable condition that the Cleveland Clinic estimates affects between 5 to 15 million Americans. Of this group, which amounts to between 2 percent to 5 percent of the American population, the ages most commonly affected are children; nearly 80 percent of people with strabismus are children from infancy to age two; less than five percent of reported cases are by adults ages sixty and over.

This is a self-diagnosable condition, and parents are able to detect this in their children during the earliest stages of development. This ailment is typically present from birth or develops within the first two to five years of life, but rare circumstances can result in the condition developing during adulthood.

Symptoms & Complaints

This is a condition in which there are not necessarily a vast array of symptoms. The signs commonly affiliated with strabismus include:

Further symptoms and common complaints are often dependent on the patient and can include the following:

  • Eye fatigue
  • The inability to move the affected eye at all
  • Feeling that one eye is actually moving in a crossed position.

Aside from physical conditions, those with this problem tend to suffer from psychological stress, due to the fact that they feel different. Frustration, sadness, and social awkwardness are common; daily activities, like driving and reading, are affected as well.

Causes

The causes of this problem are numerous, including a family history of the condition, malformations of the six muscles surrounding the eye, the nerves responsible for sending signals to the muscles being underdeveloped or damaged, and the inability of the center of the brain to control eye movement.

Other factors commonly associated with this ailment are premature birth as it can result in the underdevelopment of necessary portions of the eye, cerebral palsy, meningitis, encephalitis, abnormalities of the retina, like retinoblastoma, and fetal alcohol syndrome. Certain congenital birth defects like Down syndrome and Turner syndrome can result in crossed eye too. Additional causes could include traumatic brain injury, rubella, Apert syndrome, and Prader-Willi syndrome.

Diagnosis & Tests

Blood tests or neuroimaging scans are not typically required for this condition, as its symptoms are obvious and it can be self-diagnosed. Upon an examination, though, physicians will focus on the patient's medical history. After that collection of data, doctors will run a series of tests, including a total inspection of the eye and its surrounding portions and reflex examinations.

Cover tests are also executed and these involve a process where one eye is covered for one to two seconds to determine any shift in fixation of the uncovered eye. From there, it will be determined as to what type of strabismus the patient is exhibiting and if the condition is stable or worsening.

To determine the degree of the condition, the Hirschberg test will be administered, where the patient's eyes are examined to see where the reflection of the light shines in relation to the cornea. This will help determine the extent of the abnormality.

Treatment & Therapy

Depending on the extent of the condition, treatment measures usually equate to wearing special eyeglasses that are usually plastic rather than glass, and that are large enough so that the child cannot look over, under, or to the side of them easily. Prisms placed on spectacle lenses are also an option, a type of therapy called prism correction.

An eye patch is a tool often used to correct this problem, and surgery is sometimes required in severe circumstances in which the muscles of the eyes are unable to function at all. An injection of a botulinum toxin in the muscles of the eye may be effective and also serve as an alternative to surgery.

Prevention & Prophylaxis

Children should have regular eye screenings early in life especially those who were born prematurely or with other conditions, like Down syndrome, Turner syndrome, or retinopathy. If children need to wear glasses, it is essential that they wear them as prescribed to prevent the condition from worsening or becoming more apparent.

As parents, remaining aware of any complaints from your children or any demonstration of symptoms is important. For adults, the loss or blurring of vision, seeing double or only part of a visual field, and feeling the crossing sensation should be reported and checked immediately to avoid complications.