What is Strabismus? Causes, Types, Symptoms and Treatment



Also known as “crossed eyes”, strabismus is an eye condition in which the eyes’ ability to look towards an object together is compromised, with one of the eyes either looking out or in, or turning up and down. This abnormal behavior of the eye may be permanent or it may occur only sometimes, during illness or stressful situations, for instance.

In the United States, around 4% of the total children population is affected by strabismus. It can also affect someone in the later stages of life. Though it may run in families, but many people suffering from strabismus don’t have any relatives with the same problem.

What Causes Strabismus?

Strabismus causes can vary, with some children having unaligned eyes by birth, this condition referred as “Congenital Strabismus”. Some cases of strabismus are without a clear cause, whereas in some cases, this condition results from a problem with the nervous system, with the fault lying specifically in the part of the brain that controls the eye muscles.

Left untreated, this eye condition continues in adulthood as well. Majority of adults with strabismus are the ones born with it.  

Strabismus can also cause double vision if it appears later in life. If an adult not having strabismus as a child gets his eyes misaligned later on, it could be caused by some serious underlying condition, such as a ‘stroke’. That’s why it is advised to consult an eye doctor immediately if misalignment of the eyes or double vision appears in an adult suddenly.

A person suffering from this condition since childhood will remain able to see without getting affected by double vision. However, there can be other issues because of the eyes not aligned together, such as depth perception and the ability to see sideways (peripheral vision). Headaches and eyestrain can also be a frequent occurrence. You might also have to turn your head in unusual positions in order to see well in certain directions.

Six muscles involved in controlling eye-movement are affixed to the outside of each eye. One muscle in each eye is dedicated to move the eye to the right and one is dedicated to move the eye to the left. The remaining four muscles are meant to move the eye up or down or at an angle

Strabismus Types

Out of many, the following three are considered as the main types of strabismus:

Esotropia: “Crossed Eyes” or “Esotropia” remains the most common form of childhood strabismus, which results in one of the eyes turning inwards, towards the nose, rather than being aligned straight ahead. This form appears mostly in infants and young children.

Exotropia: Commonly referred as the “walleye”, exotropia describes the condition where one of the eyes turns outwards the temple. Symptoms of exotropia start to appear in children as young as 1 to 6 years of age.

Hypertropia: Not so common, this form of strabismus is also known as “Vertical Deviation”, one of the eyes turning upward in this form of the strabismus.

Strabismus Symptoms

The most common symptoms of strabismus include:

  • Eyes unable to look in the same direction at the same time.
  • Eyes unable to move together.
  • Inability to keep both eyes opened in bright sunlight.
  • Turning or tilting the head at a specific angle to look at an object.
  • Bumping into stuff (due to disturbed depth perception)

Sometimes, an older child may complain of tired eyes, light-sensitivity blurred vision or double vision. The frequency and intensity of strabismus symptoms may vary, getting worse particularly when a child is sick or tired.

You may also observe misalignment in the eyes of a newborn initially, but it should be fixed by 3 to 4 months. Sometimes, a wider bridge of the nose may also create ‘crossed-eyes’ appearance. However, if you find misalignment in your child’s eyes after the age of 4 months, make sure to take him for an eye exam.

Strabismus Diagnosis

The best way to diagnose strabismus is none other than an eye exam. Experts recommend that all children between 3 and 3½ years shall undergo vision assessment by an experienced pediatrician, family doctor or someone specialized in vision assessment of preschool children. Any child with possible symptoms of an eye disease should be recommended for a thorough eye exam by an ophthalmologist.

Family history of wearing thick eyeglasses or eye conditions like strabismus or amblyopia means the vision of the child should be assessed even before the age of 3. Once eye examination is completed, only then can an ophthalmologist come up with a plan for appropriate treatment of the condition.

Strabismus Treatment

Physical therapy can be recommended as one of the possible treatments of strabismus by an eye doctor, which is aimed at strengthening the eye muscles. Similarly, vision therapy is suggested sometimes to get the vision corrected in people suffering from this eye condition. This type of therapy helps your brain train to align eyes while visually processing the images. Often, vision therapy relies on computerized optical devices, including various lenses and filters, thus contributing in strengthening of the eye muscles.

Can Surgery be a Viable Option in Treating Strabismus?

Yes, surgical treatment can be prescribed to manage strabismus. An ophthalmologist might resort to surgery for strengthening or weakening the effects of one or more muscles involved in the movement of eyes. In adults, corrective surgery for strabismus is performed under local anesthesia (i.e. only the eye gets numb, while the patient remains awake).

The first step involves slitting the outer layer of the eyeball open by the ophthalmologist, which enables him to reach out to the muscle that needs to be strengthened or weakened.

When the surgery is aimed at strengthening the muscle, a small section from one end of the muscle is removed, while the rest of it is stitched back together. As a result, the remaining muscle gets shorter, helping to turn the eye toward the side of that muscle.

On the other hand, when the surgery is aimed at weakening the muscle, it involves cutting the muscle at one end without removing any of it to get it shorter. Instead, the cut is meant to produce a gap at that particular point, with the respective muscle ends tied back together with the help of a suture. As a result, the muscle tends to get longer, turning the eye further away from the side of that muscle.

This procedure is rounded up when the surgeon closes the opening in the eye by means of stitching. Double vision is normally expected to follow up the surgery for a few weeks, but this seizes to happen as the brain learns to adjust with the new way of seeing through.

Recovery time of the surgery is quite rapid in case of strabismus. Most of the children are able to resume their normal eye functions within a few days of the surgery. In fact, some cases might require more than one surgery to fix the issue. Glasses may also be required after surgery.

To conclude, make sure to regularly take your children for their scheduled eye exams, so that any irregularity about their vision can be assessed as early as possible for best possible treatment and recovery.


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