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Overview

What Is Strabismus?

Strabismus is a condition in which the eyes do not line up or move together consistently. One eye may turn inward, outward, upward or downward, while the other eye looks straight ahead. This eye misalignment may be present all the time or may come and go. Strabismus can affect children or adults.

Symptoms

Strabismus Symptoms

  • One eye turning or drifting out of alignment (crossed eyes or wandering eye)
  • Double vision (diplopia)
  • Squinting
  • Tilting the head to see more clearly
  • Closing one eye in bright light or when focusing
  • Difficulty judging depth
  • Reduced vision in one eye

Causes

What Causes Strabismus?

Coordinated eye movement depends on the eye muscles, the nerves that control them, the brain, and clear vision from both eyes. A disruption in any of these systems can prevent the eyes from aiming in the same direction. For example, a focusing problem may cause the eyes to cross, while a nerve or muscle problem may cause another pattern of misalignment.

  • Childhood developmental differences can affect how the brain learns to use both eyes together.
  • Unequal focusing needs between the eyes can interfere with coordinated vision.
  • Farsightedness may contribute to accommodative esotropia, in which the eyes turn inward when focusing.
  • Intermittent exotropia may cause an eye to drift outward, particularly when a person is tired or looking into the distance.
  • Neurologic disorders can affect the nerves or brain pathways that control eye movement.
  • Eye injury or eye disease can affect the muscles, nerves, or vision needed for normal alignment.
  • Adult-onset medical conditions, including thyroid disease, stroke, diabetes, or other disorders, may lead to new misalignment.

Risk Factors

Strabismus Risk Factors

  • A family history of strabismus or other eye alignment problems
  • Prematurity or low birth weight
  • Developmental conditions that affect vision or coordination
  • Significant uncorrected refractive error, such as farsightedness
  • Neurologic or genetic conditions
  • Previous eye disease or injury

Family history, prematurity, and many medical or genetic conditions cannot be changed. However, regular vision checks can identify treatable focusing problems or misalignment early, allowing care to begin before vision development is affected.

Complications

Strabismus Complications

  • Amblyopia, or reduced vision in one eye
  • Reduced depth perception
  • Persistent double vision
  • Visual fatigue or eye strain
  • Difficulty with school or work tasks
  • Self-consciousness or concern about appearance

Early assessment is especially important in children because visual development is time-sensitive, and untreated misalignment can contribute to amblyopia. In adults, new or persistent symptoms may interfere with reading, driving, work, or daily activities. New adult strabismus can also signal an underlying condition that requires evaluation.

Diagnosis

How Strabismus Is Diagnosed

An optometrist or ophthalmologist observes the position and movement of the eyes and measures vision separately in each eye. The examination helps identify the type and pattern of misalignment, how well the eyes work together, and whether a focusing problem or another condition may be contributing.

  • Visual acuity testing to measure how clearly each eye sees
  • Refraction to identify nearsightedness, farsightedness, astigmatism, or another focusing need
  • Cover and uncover tests to observe how each eye responds when the other eye is covered
  • Eye-movement and alignment measurements
  • Binocular-vision assessment to determine how well the eyes work together
  • A dilated eye examination when appropriate to examine the inside of the eyes

Treatment Options

Strabismus Treatment Options

Treatment for strabismus depends on the patient’s age, the type and severity of the eye misalignment, and the underlying cause. The main goals are to improve eye alignment, support normal visual development, and reduce symptoms such as double vision.

Corrective Glasses

Glasses can correct refractive errors such as myopia, hyperopia, or astigmatism. In some patients, correcting the refractive error may significantly improve eye alignment.

Patching

Patching is commonly used in children when amblyopia is present. The stronger eye is covered for a certain period to encourage the weaker eye to develop better vision.

Prism Lenses

Prism lenses can help correct small amounts of eye misalignment and reduce double vision. They may be particularly useful for some adults with symptomatic strabismus.

Vision Therapy

Orthoptic exercises may be recommended in selected cases to improve eye coordination and binocular vision. Their effectiveness depends on the specific type of strabismus.

Botulinum Toxin

Botulinum toxin injections may be used in certain cases to temporarily weaken an overactive eye muscle and improve alignment. This treatment is usually considered for specific types of strabismus.

Eye Muscle Surgery

Strabismus surgery may be recommended when the eye deviation is significant or does not improve sufficiently with other treatments. The surgery changes the position or strength of specific eye muscles to improve eye alignment.

Treatment is individualized according to the patient’s age, type of strabismus, visual function, and underlying cause. Regular follow-up with an ophthalmologist is important to monitor vision and eye alignment.

Outlook and Prognosis

Strabismus Outlook and Prognosis

The outlook for strabismus varies according to age at treatment, cause, type of misalignment, vision in each eye, and how consistently treatment and follow-up occur. Many people improve with appropriate care, although some need more than one intervention or continued monitoring.

  • Early treatment can help protect visual development, especially in children.
  • Adults may experience better eye alignment and improved control of double vision after treatment.
  • Eye alignment can recur or remain imperfect even after treatment.
  • Periodic eye examinations may still be needed to monitor vision and alignment.

When Should You See a Doctor

When Should You See a Doctor for Strabismus?

Arrange an eye examination for persistent or recurring eye turning, a child who tilts the head or closes one eye to see, new double vision, or concerns about visual development. An eye-care professional can determine whether the symptoms are caused by strabismus and whether treatment is needed.

Seek urgent care

Sudden eye misalignment needs prompt evaluation

Seek urgent medical assessment for sudden-onset strabismus, sudden double vision, severe headache, weakness, confusion, trouble speaking, unequal pupils, eye pain, or vision loss.