Esotropia: Symptoms, Causes, Diagnosis, and Treatment Options

What is esotropia?

Esotropia is an eye condition in which either one eye or both eyes turn inward towards the nose, causing them not to look straight. A more generalized term used to describe this condition is “Squint Eyes“. There are a total of 6 extraocular muscles responsible for eye movements, two of which are involved in moving the eyes sideways. When either the muscle or the nerve supplying it is affected, esotropia occurs. Esotropia is commonly manifested in infants and toddlers but can occur at any age.

Esotropia: Signs and symptoms

The most apparent sign of esotropia is misaligned eyes, with one or both eyes turning inward. Usually, the misalignment is intermittent, meaning it is only seen sometimes, but it may eventually become visible all the time during an individual’s waking hours.

In adults, if the misalignment develops, the most common symptom is double vision. However, in infants, there may not be any symptoms because their brain conveniently suppresses the affected eye, which is a physiological way of tackling double vision. This suppression can cause a condition called Amblyopia or Lazy Eye.

Both of our eyes are meant to work together, a term known as Binocular Single Vision. With the onset of esotropia, the eyes no longer fixate at the same point, resulting in a lack of depth perception for individuals with esotropia.

Causes of esotropia

Whatever the cause of esotropia, the crux of it lies in a lack of coordination between the two eyes. Usually, children with esotropia are farsighted, which means they have a “Plus” number or hypermetropia. The exact cause of esotropia can vary, and it often results from a combination of factors. Some common causes include:

1. Muscle Imbalance: The muscles that control eye movement do not work together properly, leading to an imbalance that causes one eye to turn inward.
2. Refractive Errors: Uncorrected or under-corrected refractive errors, such as hyperopia (farsightedness), can contribute to the development of esotropia. The eyes may turn inward in an effort to focus on near objects.
3. Amblyopia (Lazy Eye): If one eye has significantly reduced vision (amblyopia), the brain may suppress the input from that eye, causing the other eye to turn inward.
4. Neurological Factors: Problems with the nerves that control eye movement or with the part of the brain that processes visual information can lead to esotropia.
5. Genetic Predisposition: There is evidence to suggest that a family history of strabismus can increase the likelihood of developing esotropia.

Childhood Illness or Injury: Certain medical conditions or injuries during early childhood can contribute to the development of esotropia. Common medical history includes malnutrition, neurological illnesses, head trauma, nerve palsies, and many other systemic illnesses.

Diagnosis of Esotropia

The diagnosis of esotropia involves a comprehensive eye examination performed by an eye care professional, such as an ophthalmologist or optometrist. The examination typically includes several components to assess the alignment and overall health of the eyes. 

Here are the key steps in diagnosing esotropia:

1. Medical History: The eye care professional will gather information about the patient’s medical history, including any family history of eye conditions, developmental milestones, and any relevant symptoms or concerns.
2. Visual Acuity Testing: This assesses the clarity of vision in each eye and helps identify any refractive errors (e.g., nearsightedness, farsightedness, or astigmatism) that may contribute to esotropia.
3. Cover Test: The cover test is a fundamental part of diagnosing strabismus. During this test, the eye care professional covers one eye and observes the movement of the other eye. By alternating the cover between the eyes, they can detect any misalignment or deviation.
4. Ocular Motility Exam: This evaluates the range of eye movements and identifies any restrictions or abnormalities in eye muscle function.
5. Stereopsis (Depth Perception) Testing: This assesses the ability of both eyes to work together to perceive depth, which is often impaired in individuals with strabismus.
6. Refraction Test: This determines the need for glasses and helps correct any refractive errors that may contribute to the development of esotropia.
7. Dilated Eye Exam: The eye care professional may use dilating eye drops to enlarge the pupils, allowing a more thorough examination of the internal structures of the eye, including the retina and optic nerve.
8. Assessment of General Eye Health: The eye care professional will examine the overall health of the eyes, looking for any signs of diseases or conditions that may be associated with esotropia.

Once the diagnosis of esotropia is confirmed, the eye care professional will work on developing an appropriate treatment plan. Treatment options may include corrective lenses, vision therapy, eye patches, or, in some cases, surgical intervention to correct the underlying muscle imbalance. Regular follow-up visits may be necessary to monitor progress and make adjustments to the treatment plan if needed.

Different types of esotropia

There are different types of esotropia, classified based on various factors including age of onset, frequency, and underlying causes. Here are some common types:

1. Congenital Esotropia / Infantile Esotropia

Onset: Present at birth or within the first few months of life.

Characteristics: The misalignment is often constant, with the degree of deviation varying.

2. Accommodative Esotropia

Onset: Typically develops in infancy or early childhood.

Trigger: Associated with focusing (accommodative) effort, often due to hyperopia (farsightedness).

Characteristics: The eyes may turn inward when trying to focus on near objects. Glasses can be prescribed to correct refractive errors.

3. Intermittent Esotropia

Onset: Occurs occasionally rather than being constant.

Characteristics: The eye turn may be triggered by factors such as fatigue, illness, or prolonged near work.

4. Sensory Esotropia

Underlying Cause: Associated with reduced vision (amblyopia) in one eye.

Characteristics: The brain suppresses the input from the eye with reduced vision, leading to inward deviation of the better-seeing eye.

5. Divergence Insufficiency Esotropia

Onset: More common in adults.

Characteristics: Inward deviation of the eyes, particularly when looking at distant objects. It may be associated with difficulty maintaining proper eye alignment for distance vision.

6. Acquired Esotropia

Onset: Develops later in childhood or adulthood.

Characteristics: The misalignment may be associated with neurological conditions, trauma, or other health issues.

Esotropia Eyes: Treatment Options in children and adults

The treatment for esotropia depends on factors such as the type, severity, and underlying causes of the condition. Treatment aims to realign the eyes, improve vision, and address any contributing factors. Here are some common treatment options for esotropia:

1. Corrective Lenses

Purpose: If refractive errors, such as hyperopia (farsightedness), contribute to esotropia, corrective lenses (glasses or contact lenses) may be prescribed to help focus light properly on the retina.

2. Prism Lenses

Purpose: Prism lenses may be used to alter the way light enters the eyes, helping to reduce the eye turn. They can be incorporated into glasses to help alleviate symptoms, especially in cases of intermittent esotropia.

3. Vision Therapy

Purpose: Vision therapy involves a series of eye exercises and activities designed to improve eye coordination, focusing abilities, and overall visual skills. It can be particularly beneficial for certain types of esotropia, such as accommodative esotropia.

4. Eye Patching

Purpose: Patching the dominant eye (the eye that is not turning) can be used to encourage the use of the eye with esotropia, particularly in cases of amblyopia (lazy eye). This helps improve visual acuity in the affected eye.

5. Bifocals or Progressive Addition Lenses

Purpose: In cases of accommodative esotropia, bifocal or progressive addition lenses may be prescribed to provide clear vision for both near and distance tasks.

6. Surgery

Purpose: Strabismus surgery may be recommended to correct the alignment of the eyes by adjusting the length or position of the eye muscles. Surgery is often considered when other treatments are not effective or when there is a significant degree of eye turn.

Esotropia and Esophoria: Understanding the Difference

Even though esophoria may sometimes develop symptoms in certain individuals, treatment may not be necessary. Addressing and treating the underlying cause of symptoms will resolve manifestations induced by esophoria.

Tips for Coping with Mild Esotropia

Mild esotropia may not interfere with binocular vision as much as other severe types of esotropia. Some ways to cope with mild esotropia include:

1. Regular Eye Checkups.
2. Wearing corrective lenses if you have been found to have any refractive errors.
3. Sometimes, excessive screen time may lead to a temporary form of esotropia. Following the 20-20-20 rule—taking a 20-second break to look at something 20 feet away every 20 minutes—can reduce the chances of developing mild esotropia for excessive screen users.

When should I see a healthcare professional for my esotropia?

If you suspect or observe any signs of esotropia, it is advisable to consult with a healthcare provider, preferably an eye care specialist. Here are some situations when you should seek medical attention for esotropia:

1. Visible Eye Misalignment: If you notice that one or both of your eyes consistently turn inward or cross, it’s important to see an eye care professional for a comprehensive eye examination.

2. Changes in Eye Alignment: If there are sudden changes in eye alignment, especially in children, it’s crucial to seek prompt medical attention. Rapid changes could indicate underlying issues that need evaluation.

3. Double Vision: If you experience double vision, particularly when looking at objects at a distance or up close, it may be a symptom of esotropia or another eye condition.

4. Squinting or Closing One Eye: If you find yourself squinting or closing one eye to see more clearly, it could be a compensatory mechanism to alleviate double vision caused by esotropia.

Conclusion: Strengthening Individuals Affected by Esotropia

In conclusion, esotropia is not a serious ailment, and there won’t be any life-threatening consequences depending upon the cause of esotropia. Regular eye checkups, especially in infants and toddlers, are important to detect esotropia early and ensure timely treatment. This ensures that vision development in children occurs normally.

Frequently Asked Questions