Crossed eyes occur when the eyes do not align properly and cannot work together as they typically would. The eyes may point in different directions, and it may cause vision difficulties.

Crossed eyes is a misalignment of the eyes in which the eyes do not point in the same direction at the same time. The medical term for crossed eyes is strabismus.

With normal vision, the eyes point in the same direction in order to see properly. With crossed eyes, one eye may point forwards, while the other may point inward, outward, upward, or downward.

Strabismus may affect one eye, or the eyes may alternate in turning in different directions.

There are different types of strabismus, depending on which way the eyes turn. Esotropia is an inward turning, exotropia is an outward turning, and hypertropia is an upward turning.

In the United States, crossed eyes affect roughly 4% of the population.

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Signs that a person may be cross-eyed include:

  • the eyes appear misaligned
  • eyes may not move together at the same time
  • tilting the head when looking at things
  • problems with depth perception

Signs in children to look for include misaligned eyes in a child older than 3 months, even if only occasionally, and if a child turns their head from side to side when looking at things.

Parents will need to speak with an eye doctor if they suspect a child has crossed eyes.

There are six muscles that control eye movements, which allow the eye to move in different angles including up and down, and to the right and left.

The brain controls these muscles in order for them to work together and allow the eye to focus on a single point.

Any problem affecting these muscles may cause crossed eyes, including:

  • certain health conditions, such as
  • injury or trauma to the head
  • damage to the eye muscles through eye surgery or trauma

Although crossed eyes can develop later in life due to any of these factors, it is more common for the condition to occur in childhood.

One of the most common causes of esotropia in children is high hyperopia (far-sightedness).

Crossed eyes can occur in children who have no other health issues. The condition is more likely to occur in children who are premature, have a brain disorder, such as cerebral palsy, Down syndrome, or a brain tumor.

To diagnose crossed eyes, an eye doctor will take a medical history, assess any symptoms, and carry out a range of tests such as:

  • Visual acuity: People will need to read letters on a reading chart at different distances to check how close they need to be to the letters to see them clearly.
  • Refraction: A doctor will place different lenses in front of the eye to see if a person needs lenses to compensate for any vision problems.
  • Alignment and focusing: These tests show how well the eyes are able to move and work together to focus on a single image.
  • Eye health examination: A doctor will examine the health of the internal and external structures of the eyes to check for any eye disease. A doctor may use eye drops to temporarily affect how the eyes focus.

The combination of these tests helps an eye doctor to diagnose crossed eyes or identify any other conditions that may require treatment.

Risk factors for crossed eyes include:

  • having parents or siblings with crossed eyes
  • uncorrected farsightedness, which causes extra focusing of the eyes to see objects clearly
  • certain medical conditions, such as:
    • Down syndrome
    • cerebral palsy
    • stroke
    • head injury

Treatment for crossed eyes may include the following:

Eyeglasses or contact lenses

In some cases, wearing corrective eyeglasses or contact lenses may be enough to treat crossed eyes.

Prism lenses

Prism lenses have one lens that is thicker than the other. This alters the amount of light that enters the eye and, by bending the direction of light, makes the two images from each lens appear closer together. This reduces the need to turn one eye to see more clearly.

Vision therapy

Eye exercises may help to improve how the eyes focus and move together. Vision therapy supports the connection between the eyes and brain, helping them to work together better.

Surgery

Surgery can alter the length or position of the eye muscles to straighten the eyes. People may need vision therapy following eye surgery in order to prevent the eyes from becoming cross-eyed again.

Botox

An injection of botulinum toxin into the eye works to paralyze eye muscles that prevent correct alignment. This treatment may last for a few months or could lead to permanent results.

Early diagnosis and treatment of crossed eyes can usually lead to excellent treatment outcomes.

According to the American Academy of Ophthalmology (AAO), people can also seek treatment for crossed eyes later in life and do not need to continue living with any discomfort or vision problems from the condition.

Crossed eyes is a misalignment of the eyes where they are unable to work together properly and are unable to focus on the same point at the same time. One eye may face forwards, while the other may turn in another direction.

People with crossed eyes may have eyes that appear misaligned, have difficulties with depth perception, or have double vision.

An eye doctor can carry out a number of tests to check how the eyes focus and align in order to diagnose crossed eyes.

Treatment can usually successfully treat crossed eyes. Treatment options include vision aids, such as prescription glasses, prism lenses, eye exercises, or eye surgery to correct the alignment of the eyes.