Esotropia is a condition where one or both eyes turn inward. The term derives from Greek, where 'eso-' means 'inward,' and 'trope' means 'turn.'

Approximately 1 to 2 percent of all people in the United States have esotropia, according to the College of Optometrists in Vision Development.

Esotropia can take several forms, with some types developing in infancy and others occurring in adulthood.

Fast facts on esotropia:

  • Those with esotropia often look like they have crossed eyes.
  • The condition is sometimes mistakenly referred to as lazy eye.
  • Untreated esotropia may cause complications in both children and adults.
  • Esotropia is a type of eye misalignment, known as strabismus.

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Esotropia may cause a range of complications, making early diagnosis and treatment important.

According to the American Association for Pediatric Ophthalmology and Strabismus (AAPOS), esotropia can be classified by its frequency, the person's age when it develops, and whether it is related to eye-focusing or not.

The different classifications include:

Infantile

The infantile form of the condition begins during the first year of life. Infants with this condition are unable to use their two eyes together.

If one of the eyes turns inward more often than the other, the child is at higher risk of amblyopia, also known as lazy eye.

Infantile esotropia is usually treated with surgery, eyeglasses or, sometimes, Botox injections. Correcting esotropia before a child is 2 years of age is often very successful, with just a few children experiencing visual problems as they grow up.

Other eye problems associated with infantile esotropia include an upward drifting of the eyes, farsightedness, and nystagmus, which is a jerking movement of the eyes.

Acquired

If esotropia develops later in life, it is known as acquired esotropia. It may result from medical conditions, such as diabetes, or other eye problems, such as untreated farsightedness.

Double vision is one of the leading complaints of those with the condition. It can make everyday tasks difficult.

People with acquired esotropia can often successfully treat the condition with glasses and vision therapy, although surgery may be necessary for some.

One of the most common forms of strabismus (crossed eye), accommodative esotropia is characterized by eye crossing that occurs when the eyes are trying hard to focus to see objects clearly.

This attempt at focusing is known as "accommodation." People with accommodative esotropia — also known as refractive esotropia — usually have farsightedness.

People can control accommodative esotropia by wearing prescription eyeglasses or contact lenses. If this fails, they may require surgery.

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Esotropia causes one or both eyes to turn inwards.
Image credit: Kakawere, (2010, March 20)

In addition to the types listed above, esotropia may be classified as constant or intermittent.

Constant esotropia is present all the time, while intermittent esotropia comes and goes.

For example, intermittent esotropia may only be noticeable when a person is:

  • tired
  • sick
  • looking only at objects that are near
  • looking only at objects that are far away

Symptoms of esotropia include:

  • inward turning of the eyes
  • crossing of the eyes
  • lazy eye

People with esotropia may notice that they cannot focus their eyes on the same place at the same time, and they may only be able to see objects fully with one eye.

Infants and young children may experience:

  • loss of 3-D vision
  • issues with depth perception
  • amblyopia (loss of vision in the crossed eye)

However, if congenital esotropia is treated in infancy, such complications are less likely to be experienced long-term.

Older children and adults that acquire esotropia can develop:

  • diplopia (double vision)
  • decreased binocular vision (the ability of the eyes to work together)
  • depth perception issues

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Strabismus may be inherited in some cases, although not all family members will exhibit the condition, or the same form of the condition.

There are several forms of strabismus, with esotropia being the most common.

Some people are born with esotropia while others develop it later in life. There is a hereditary component to strabismus, and the condition tends to run in families.

However, not all family members will develop strabismus, and those that are affected will not necessarily experience the same forms.

Risk factors

Some factors increase the risk of having esotropia, including:

  • a family history of strabismus
  • having another eye disorder, such as cataracts or glaucoma
  • certain medical disorders, such as diabetes and overactive thyroid
  • neurological conditions, including excessive fluid in the brain
  • premature birth
  • stroke

There are no known risk factors for childhood esotropia.

People with symptoms of esotropia will usually be examined by an eye doctor, ophthalmologist, or optometrist, who will take a complete medical and family history before carrying out eye examinations.

The examinations used will test for:

  • clarity of vision in each eye
  • clarity of vision in both eyes together
  • how well the eye refracts light
  • the degree of farsightedness
  • retinal function

The treatment for esotropia depends on the severity of the condition, and the length of time it has been present.

Other factors informing the treatment plan include whether misalignment is present in one or both eyes, and whether the esotropia is accommodative or not.

Treatment always aims at:

  • eye alignment
  • correcting double vision
  • reducing vision problems with both eyes
  • correcting lazy eye

Treatment options include:

  • Glasses or contact lenses: This is often the first line of treatment. Prescription glasses can correct eye misalignment or farsightedness. If a person's eyes still cross while wearing the glasses, they may require a bifocal lens.
  • Vision therapy: Eye exercises may help to strengthen the eye function and the muscles around the eye to improve vision. One form of vision therapy involves wearing a patch over the unaffected eye to improve the function of the crossed eye.
  • Botox injections: Botox may be injected to realign the eyes of some people who have mild esotropia.
  • Surgery: Some people may require surgical treatment to change the length of the muscles around their eyes, although this does not always completely remove the need to wear glasses or contact lenses.

Surgery is mainly performed on infants with esotropia, but some adults may also undergo a surgical procedure.

Esotropia may resolve without any intervention in infants less than 5 months old, especially if the symptoms are mild and the eye misalignment is intermittent.

Esotropia affects just 1 to 2 percent of the population, but it is the most common form of eye misalignment. The condition can be acquired or present at birth.

The outlook for esotropia depends on its severity and type. Sometimes, infantile esotropia will resolve spontaneously in the first few months of a baby's life, while other times, it will require treatment, such as glasses or surgery.

Many children who receive treatment at a young age do not experience vision problems as they grow up.

Esotropia that develops in later childhood or adulthood can usually be managed with glasses or contact lenses, as well as by treating any underlying conditions that may be contributing to symptoms.