Strabismus in Childhood

Description

Strabismus or squint/crossed eyes , occurs when there is a misalignment or lack of co-ordination between the two eyes. Generally with this condition, the two eyes point in different directions. The misalignment is a result of the failure of the eye muscles to work together properly, caused by muscle weakness in the eye (leading to uneven muscle development), injury, other eye diseases, a brain tumour, or a tumour in the eye (cf. childhood cancer ).
It is usually diagnosed in childhood, but can also occur later in life. An estimated 4% of American children have some degree of crossed eyes and it affects boys and girls equally. Most children with crossed eyes are otherwise normal, but there is a high incidence of this disorder in children with cerebral palsy and hydrocephalus. Crossed eyes often worsen when eye muscles are tired-for example, late in the day, in bright sunshine, or during the course of an illness. Crossed eyes sometimes cause double vision in children, but more commonly does in adults. If untreated, crossed eyes are likely to worsen with age. Crossed eyes are classified by the way the eye deviates:

• Esotropia or convergent strabismus . The most common form, which occurs when the eye turns in toward the nose. More than 50% of children with crossed eyes have this form.
• Accommodative esotropia is a variation in farsighted children whose eyes cross because of the effort to focus.
• Exotropia or divergent strabismus , sometimes called walleye , occurs when the eye drifts outward. Sometimes eyes will drift up or down.
• False or pseudo-strabismus is a condition in infants that looks like crossed eyes but is not. In fact, the appearance of crossed eyes is caused by an extra fold of skin that some children have near the inner eye, a broad flat nose, or eyes that are unusually close together. Pseudo-strabismus will disappear as the child's face grows.

Symptoms and Signs

The most common symptoms and signs of strabismus include:

• Mis-aligned eyes and uncoordinated eye movements, either constant or intermittent;
• Squinting
• Tilting head to look at things
• Frequent eye movements
• Headache
• Rubbing of eyes
• Tearing
• Double vision

Diagnosis and Treatment

The doctor will usually check for deviations in eye movement, if the child has an inability to keep one eye fixed on an object and if visual acuity is poor in one or both eyes, to confirm a diagnosis of strabismus.
Treatments range from glasses to surgery. Glasses can be used to correct mild crossed eyes, by improving focusing and redirecting the line of vision. Sometimes an eye patch over the strong eye helps the weak eye focus. Exercises may also be prescribed to strengthen the weak eye. In some cases, drops are put in one eye, clouding vision and forcing the weaker eye to take over.
Surgery either strengthens or weakens an eye muscle in order to balance a pair of muscles.
In a relatively new medical technique, a medication called botulinum (Botox) is injected into an eye muscle. This temporarily weakens and relaxes the muscle and allows the opposing muscle to tighten. The effect of the medication wears off in several weeks, but the correction may be permanent.
With timely and appropriate treatment, the prognosis is excellent. Most of the time crossed eyes can be corrected, both for visual and cosmetic effects.

The information in this page is presented in summarised form and has been taken from the following source(s):
1. Intelihealth.com, Children's Health Section: http://www.intelihealth.com/