Exotropia: Symptoms, Types, Causes and Treatment

Exotropia is a type of strabismus where one or both eyes turn outward. It can affect people of all ages but is most commonly diagnosed in childhood. Understanding exotropia involves recognizing its symptoms, distinguishing between its types, identifying underlying causes, and exploring available treatments. This article provides a comprehensive overview based on the latest research and clinical studies.

Symptoms of Exotropia

Exotropia can present in subtle ways or with clear, noticeable symptoms. Recognizing these signs is essential for early intervention and better visual outcomes. Patients may experience both visual and physical symptoms, which can impact daily activities, appearance, and quality of life.

Symptom	Description	Frequency/Impact	Source
Eye Deviation	Outward turning of one or both eyes	Most common, visible sign	3 4 5 10
Double Vision	Seeing two images of a single object	Occasional, especially in IXT	3 11
Eye Fatigue	Tiredness or discomfort after visual tasks	Common during prolonged focus	1 2 3
Appearance	Noticeable squint or misalignment	Social/psychological effects	2 10

Table 1: Key Symptoms

Outward Eye Deviation

The hallmark symptom of exotropia is the outward turning of one or both eyes. This misalignment can be constant or intermittent, often becoming more noticeable when a person is tired, daydreaming, or looking into the distance. The deviation can sometimes switch from one eye to the other (alternating exotropia) or affect only one eye consistently (monocular exotropia) 4 5 10.

Visual Disturbances

Patients may experience double vision (diplopia), particularly when the exotropia is intermittent (IXT). In some cases, especially with longstanding exotropia, the brain may suppress the vision from the deviating eye to avoid double vision, leading to reduced depth perception 3 11.

Eye Fatigue and Discomfort

Eye fatigue, or asthenopia, is a frequent complaint, especially during activities that require intense focus, such as reading or watching screens. Headaches and dizziness can also occur, particularly in demanding visual environments like 3D displays 1 2 3.

Impact on Appearance and Psychosocial Well-being

Beyond physical symptoms, exotropia can have significant psychosocial consequences. Children and adults may feel self-conscious about the visible misalignment, leading to decreased self-esteem and social interaction difficulties 2 10.

Types of Exotropia

Exotropia is not a one-size-fits-all condition. It manifests in several forms, each with unique patterns and clinical implications. Accurate classification is crucial for effective management.

Type	Distinguishing Feature	Prevalence/Notes	Source
Intermittent Exotropia	Occasional outward drift, especially at distance	Most common in children	4 5 8 10
Constant Exotropia	Eyes always turned outward	Less common, more severe	2 5 6
Sensory Exotropia	Occurs due to vision loss in one eye	Often from eye disease	5 10
Congenital/Infantile	Present before 12 months of age	Rare	5 6 9
Paralytic Exotropia	Due to nerve/muscle paralysis	Uncommon	5 10 11
Convergence Insufficiency	Exotropia greater at near than at distance	Seen in older children	4 5 8

Table 2: Exotropia Types

Intermittent Exotropia (IXT)

Intermittent exotropia is by far the most common form, especially in childhood, accounting for nearly half of all exotropia cases 4 5 8. In IXT, the eye(s) drift outward only some of the time—often when the patient is fatigued, daydreaming, or looking at distant objects. Control over eye alignment is typically better at near than at distance.

Subtypes of Intermittent Exotropia

• Basic Type: Similar deviation at distance and near (most common) 8.
• Divergence Excess: Deviation is larger at distance than near.
• Convergence Insufficiency: Deviation is larger at near than at distance 4 5 8.

Constant Exotropia

Here, the eye(s) are always turned outward. Constant exotropia is less common and generally considered more severe because it often leads to persistent visual problems and can affect depth perception more profoundly 2 5 6. It may arise as a progression from untreated intermittent exotropia.

Sensory Exotropia

Sensory exotropia occurs when vision loss or reduced vision in one eye disrupts normal binocular alignment. Causes include cataracts, retinal disease, or severe amblyopia. This type can develop at any age but is more likely when the vision problem arises during the years when visual development is most sensitive 5 10.

Congenital (Infantile) Exotropia

This rare type presents in infancy, usually before 12 months of age. It's often associated with broader neurological or anatomical abnormalities, such as an increased biorbital angle (a wider-than-normal space between the eye sockets) 5 6 9.

Paralytic Exotropia

Paralytic exotropia results from paralysis or dysfunction of the nerves or muscles that control eye movement. It can be acquired through trauma, neurological disease, or after certain surgeries 5 10 11.

Convergence Insufficiency

This form is characterized by greater outward deviation when looking at near objects rather than far ones. It may be underdiagnosed but is especially relevant for school-aged children who have trouble reading or focusing on close work 4 5 8.

Causes of Exotropia

Understanding what causes exotropia helps inform both prevention and treatment strategies. Causes can range from developmental issues to acquired problems affecting the eye muscles, nerves, or vision.

Cause Type	Example/Description	At-Risk Groups/Notes	Source
Genetic/Developmental	Family history, abnormal anatomy (e.g., biorbital angle)	Infants, young children	4 5 9
Sensory Loss	Amblyopia, cataracts, retinal disease	Any age, often children	5 10
Neurological	CNS disorders, developmental delay	Children with neurological issues	5 10
Trauma	Orbital or facial injury affecting eye muscles/nerves	All ages, post-accident	11
Refractive Error	Uncorrected vision problems (e.g., hyperopia, myopia)	Children	10

Table 3: Common Causes of Exotropia

Genetic and Developmental Factors

A family history of strabismus increases the risk of developing exotropia. Anatomical differences, such as a wider-than-normal biorbital angle (especially in infantile exotropia), may predispose children to the condition 4 5 9.

Sensory Loss

When vision in one eye is significantly reduced or lost, the brain may have difficulty coordinating the eyes, leading to sensory exotropia. Common causes include untreated amblyopia, cataracts, or other eye diseases that impair vision 5 10.

Neurological Causes

Neurological disorders, such as cerebral palsy, developmental delay, or congenital abnormalities of the central nervous system, can contribute to the development of exotropia. These cases may present with additional eye movement abnormalities 5 10.

Trauma

Exotropia can occur after trauma to the eye socket or surrounding structures, especially if the muscles or nerves controlling eye movement are damaged. Sometimes, exotropia may be transient and resolve as swelling or nerve dysfunction improves 11.

Refractive Errors

Significant uncorrected refractive errors (such as hyperopia or myopia) can disrupt normal binocular vision. In some cases, correcting these errors with glasses can improve alignment, particularly in children 10.

Treatment of Exotropia

Management of exotropia is tailored to the type, severity, age of the patient, and underlying cause. Treatments range from observation and non-invasive therapies to surgical interventions.

Treatment	Description/Approach	Effectiveness/Notes	Source
Observation	Watchful waiting for mild/intermittent cases	Low risk, sometimes sufficient	8 14
Glasses	Correct refractive errors	Can improve control	10 15
Patching	Covering one eye to improve control	Slightly reduces deterioration	14
Overminus Lenses	Glasses with extra minus power to stimulate convergence	Temporary control improvement, possible myopic shift	15
Botulinum Toxin	Injection to weaken overactive muscles	Effective in some children	13
Surgery	Realignment of eye muscles	High success, recurrence possible	2 7 12 16

Table 4: Main Treatment Options

Observation

For many children with intermittent exotropia, especially those with good control and minimal symptoms, observation is a reasonable option. Studies show that deterioration over a six-month period is uncommon, and some cases may remain stable or even improve without intervention 8 14.

Glasses and Overminus Lens Therapy

Correcting refractive errors can improve alignment in some children. Overminus lens therapy uses glasses with extra minus lens power to stimulate convergence and improve control of exotropia. While beneficial during treatment, its effects typically do not persist after discontinuation and it may increase the risk of myopic shift (increased nearsightedness) 15.

Patching

Part-time patching (covering one eye for a few hours each day) is sometimes used to improve control or prevent deterioration. Studies show a slight benefit over observation, but both approaches are considered reasonable for mild cases 14.

Botulinum Toxin Injections

Botulinum toxin (Botox) can be injected into the lateral rectus muscles to temporarily weaken them and help realign the eyes. This approach is particularly effective for some children, especially those aged 2 to 4.5 years, with outcomes comparable to surgery in selected cases 13.

Surgical Treatment

Surgery is typically recommended for moderate to severe exotropia or when non-surgical methods fail. The procedure involves adjusting the eye muscles to improve alignment. Success rates are high, but recurrence can occur, particularly for large-angle or persistent cases. Both two- and three-muscle surgeries are effective, and some types (e.g., pseudo-divergence excess) have better outcomes than others 2 7 12 16.

Postoperative Outcomes

Surgical correction often leads to improvements in both appearance and symptoms such as eye fatigue or depth perception. However, some patients may require additional surgeries, especially if the deviation recurs or if there are changes in binocular vision over time 2 7 16.

Conclusion

Exotropia is a complex, multifaceted condition with significant visual and psychosocial implications. Early recognition and tailored management improve outcomes for most patients. Here’s a summary of key takeaways:

• Symptoms include outward eye deviation, double vision, eye fatigue, and psychosocial impact.
• Types range from intermittent to constant, sensory, congenital, paralytic, and convergence insufficiency.
• Causes are diverse—genetic, developmental, sensory loss, neurological issues, trauma, and refractive errors.
• Treatment is individualized and may involve observation, glasses, overminus lenses, patching, botulinum toxin, or surgery, with good outcomes in most cases.

Staying informed and seeking timely evaluation are crucial steps in managing exotropia and preserving visual function and quality of life.