EXPLAINER: What to know about crossed eyes

At some point in your life, you may have encountered someone whose eyes are directed opposite to where they are actually looking. As a child, you might have even tried to mimic their eye position and question the reason their eyes are like that. This condition is commonly referred to as crossed eyes, but medically it is known as strabismus.

Strabismus is a prevalent condition that can affect people of all ages, with a higher incidence in children.

According to Brian G. Mohney, a pediatric ophthalmologist, approximately 1 in 20 children experiences strabismus.

Without further ado, here is what you need to know about strabismus.

WHAT IS STRABISMUS?

Strabismus is a vision disorder in which the eyes do not properly align with each other when looking at an object. In other words, one eye is turned in a direction that is different from the other eye.

Normally, the six muscles that control eye movement work together and point both eyes in the same direction.

However, if one has strabismus, these muscles have issues controlling eye movement and can not keep a normal eye position.

The American Association for Pediatric Ophthalmology and Strabismus (AAPOS), reveals that there are different types of strabismus, according to the direction the eyes turn.

• Esotropia: This is a type of strabismus that causes inward deviation of the eyes. It is characterized by having one or both eyes turn inward toward the nose. Esotropia is the most common type of strabismus and affects between 2 to 4 percent of children.
• Exotropia: This type of strabismus is also called wall-eye. It is when one or both eyes turn outward toward the ear and it affects 1 to 1.5 percent of kids.
• Hypertropia: This is characterized by an upward deviation of one or both eyes. In this condition, the eyes are misaligned with one pointing upward.
• Hypotropia: This is the opposite of hypertropia. It is the downward deviation of one or both eyes where the eyes are misaligned with one pointing downward.

What causes strabismus?

Strabismus is mostly caused by an imbalance in the muscles responsible for controlling the movement of the eyes.

However, there are other causes which include:

• Genetic factors: People who have a family history of strabismus are at risk of having the condition. Research has found that about 30% of children with strabismus have a family member with a similar condition.
• Acquired factors: Strabismus can be caused due to eye injuries or diseases that affect the eye muscles or nerves.
• Refractive error: Uncorrected farsightedness can contribute to strabismus because of the additional eye focus they must do to keep objects clear.
• Neurological or brain development issues: People suffering from conditions such as stroke, down syndrome, and cerebral palsy are at risk of strabismus.

What are the symptoms of strabismus?

Symptoms of strabismus can differ in severity depending on the type and the cause. However, here are the common symptoms of strabismus.

• Eye misalignment
• Double vision
• Frequent blinking or squinting, especially in bright sunlight
• Tilting of head to look at things
• Eye strain
• Closing one eye when looking at objects that are far away or when you’re in bright light

How is strabismus treated?

There are several treatment options for strabismus ranging from nonsurgical to surgical. Strabismus is advised to be treated quickly — also the younger the patient the more effective the treatment is likely to be.

These treatments include:

• Eyeglasses and lenses: In a situation where strabismus is caused by refractive error, corrective lenses can help keep the eyes straight.
• Medications: Medications like eye drops, ointments as well as botulinum toxin injection (Botox)  are used. Botox helps weaken the overactive eye muscle and align the eyes properly.
• Vision therapy: This involves a series of exercises and activities that help improve eye coordination, focusing ability and eye muscle control.
• Eye muscle surgery: This is done if other treatments are not effective. During this surgery, the eye muscles are moved to change the length or position of the muscles so the eyes are aligned correctly.

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