Health Library

What Is Strabismus?

Strabismus is when eyes don’t line up or when one or both eyes wander. The eyes may turn:

• inward (called esotropia or “cross-eyed”)
• outward (exotropia)
• up (hypertropia)
• down (hypotropia)

When eyes don’t line up together, the straight or straighter eye becomes dominant. The vision strength (acuity) of this eye stays normal because the eye and its connection to the brain are working as they should. The misaligned or weaker eye, though, doesn’t focus as it should and its connection to the brain doesn’t form correctly.

Sometimes, strabismus (streh-BIZ-mis) is very noticeable. Other times, it might only be noticed when a child is tired or looking at something very closely.

Strabismus usually can be fixed when found and treated early. If it’s not treated, the brain eventually will ignore the visual images of the weaker eye. This change — called amblyopia, or “lazy eye” — can make vision blurry, cause double vision, and harm a child’s depth perception (seeing in 3D). These problems can become permanent if they’re not treated. 

What Causes Strabismus?

Kids can be born with strabismus or develop it in childhood. Often, it’s caused by a problem with the muscles that move the eyes, and can run in families.

Most kids with strabismus are diagnosed when they’re between 1 and 4 years old. Rarely, a child might develop strabismus after age 6. If this happens, it’s important for the child to see a doctor right away to rule out other conditions.

What Are the Signs of Strabismus?

Most kids with strabismus don’t complain of eye problems or notice changes in their vision. Usually, it’s a family member, teacher, or health care provider who notices that the eyes are not straight.

Some kids may complain of double vision (seeing two objects when only one is in view) or have trouble seeing things in general. These problems also can affect reading skills and classroom learning. Younger kids who aren’t talking yet may squint a lot and turn or tilt their heads in an attempt to see more clearly.

If your child has any of these signs or symptoms, tell your health care provider. He or she can refer you to a pediatric ophthalmologist for care, if needed.

How Is Strabismus Diagnosed?

It’s normal for a newborn’s eyes to wander or cross occasionally during the first few months of life. But by the time a baby is 4–6 months old, the eyes usually straighten out. If one or both eyes continue to wander in, out, up, or down — even once in a while — it’s probably due to strabismus.

How Is Strabismus Treated?

The earlier strabismus is treated, the better. That’s because key connections between a child’s eyes and brain form by about 8 years old.

Treatment for strabismus may include:

• eyeglasses
• eye patching
• eye drops
• eye muscle surgery

Sometimes, wearing eyeglasses is enough to straighten out the eyes. If not, a child might be given an eye patch to wear over the straight eye for a few hours a day. This patch makes the weaker eye do the “seeing” work. Over time, the muscles and vision in the weaker eye become stronger.

Getting a baby or toddler to accept wearing an eye patch can be a challenge. But most kids get used to the patch. Wearing it becomes part of their daily routine, like getting dressed in the morning.

Sometimes, though, kids refuse to wear an eye patch. Then, eye drops (called atropine drops) might be used instead. Just as eye patching blocks the vision in the straight eye, the atropine drops temporarily blur out vision in that eye. This makes the weaker eye work harder so that eye muscles and vision get stronger.

If eyeglasses, eye patching, and/or atropine drops can’t fix a child’s strabismus, eye muscle surgery might be needed. Surgery involves loosening or tightening the muscles that cause the eye to wander. Most kids can go home the same day of surgery.

What Else Should I Know?

Regular eye exams are the best way to detect strabismus. Early diagnosis and treatment better a child’s chances of having straight eyes and developing good vision and depth perception. But older kids and teens (and even many adults with strabismus) can still be helped by treatment.

Also keep in mind the social aspect to strabismus. Aligned eyes are important for a healthy self-image in adults and kids.