The misalignment of eyes that causes them to point in different directions is called as strabismus. It is normally called as crossed eyes in non-medical terms. The eye can turn in (crossed-eyed/ estropia), out (wall-eyed/ exotropia), up (hypertropia) or down (hypotropia). This happens due to poor eye muscle control in most cases or severe farsightedness.
Strabismus or cross-eyed or wall-eyed is a vision problem where the eyes do not align simultaneously under normal conditions. One eye may turn constantly and may turn intermittently, that is, only under stress or when seriously ill. Both, constant and intermittent strabismus requires treatment and will not resolve on its own.
Strabismus may affect only one eye called as unilateral strabismus or may affect both eyes alternatively called as alternating strabismus. About 4% of the US population has some type of strabismus.
Symptoms of Strabismus
- Eyes do not look in the same direction at the same time
- Eyes do not move together in the same direction
- One may squint in bright sunlight
- Turning head or tilting head to look at an object
- Depth perception reduces leading to inability to gauge depth
Causes of Strabismus
There are 6 muscles attached to the eye that help control the eye movement. The brain sends these muscles direct signals to make them move. Problems with the control center within the brain, the nerves or the eye muscles can lead to Strabismus. Other factors that can lead to strabismus include:
- Family history of strabismus, but many individuals without a family history develop strabismus
- People with hyperopia or uncorrected farsightedness also develop refractive error, as they strain their eyes to focus objects clearly
- People with medical conditions like cerebral palsy, Down syndrome, stroke, head injury, etc. are at risk of developing strabismus
- A head injury, eye or blood vessel damage, eye tumor or brain tumor, Graves’ disease and various nerve disorders can lead to strabismus
Diagnosis of Strabismus
An eye examination helps diagnose strabismus. The doctor tries to analyze the way the eye focuses and moves. The vision acuity is measured to see the person’s ability to read letters from a distance of 20 feet. A refraction test to find out the type of lens required by the patient to correct refractive error. A test to check how well the eyes move and focus together. And test to check the health of the eye from outside and within.
Treatment of Strabismus
Strabismus treatment involves improvement of alignment of the eyes. Thus, the treatment includes:
- Eye glasses to improve farsightedness
- Eye exercises to train the brain and eyes to function in sync
- Prism lenses, that is, special lenses with a prescription for prism power. They alter the light that enters the eye and reduces the amount of turning to focus on objects
- Eye patch on the good eye to force the lazy eye or weak eye to work harder
- Surgery in some cases to correct the eye muscles
Prognosis for Strabismus
The prognosis for strabismus is good if one gets early treatment. Vision problems may however remain.
Strabismus requires treatment. If left untreated, it could lead to permanent reduction in vision of the affected eye.