Strabismus

Strabismus is a condition in which the two eyes do not point in the same direction at the same time. It may appear in childhood or adulthood and can affect binocular vision, depth perception, eye comfort and, in children, normal visual development.

Overview

Strabismus is eye misalignment: the two eyes do not look at the same point at the same time. One eye may focus on an object while the other turns inward, outward, upward or downward. The condition is sometimes called crossed eyes, squint, wall eye or an eye turn, but the medical term is strabismus.

Normal vision depends on both eyes working together. When the eyes are aligned, the brain combines the images from each eye into one three-dimensional picture. This is called binocular vision. In strabismus, the brain receives two different images. A child’s brain may suppress, or ignore, the image from the turned eye, while an adult may experience double vision because the brain is already used to using both eyes together.

Strabismus can be constant or intermittent. It may be present from infancy, develop in childhood, or appear later in life. Some forms are more noticeable when a person is tired, ill, focusing on near objects, looking into the distance or daydreaming. The direction of the eye turn helps doctors describe the condition: esotropia means inward turning, exotropia means outward turning, hypertropia means upward turning and hypotropia means downward turning.

Strabismus is not only a cosmetic concern. In children, it may interfere with visual development and depth perception, and it may be associated with amblyopia, commonly known as lazy eye. In adults, it may affect reading, driving, balance, work tasks and confidence. With careful assessment, many people can be helped with optical, medical, rehabilitative or surgical treatment options.

Symptoms

The main symptom of strabismus is visible eye misalignment. A parent, teacher, family member or the person themself may notice that one eye does not stay straight, especially in photographs, when focusing, or when tired. The eye turn may happen all the time or only from time to time.

Symptoms can vary by age. Young children often do not complain because the brain may adapt by suppressing the image from one eye. Adults are more likely to notice uncomfortable symptoms because their visual system is already fully developed and may not easily suppress a second image.

• One eye turning inward, outward, upward or downward
• Eyes that do not appear to move together
• Double vision, especially in adults or older children
• Closing or covering one eye to see better
• Head tilting or turning to reduce double vision or improve focus
• Poor depth perception, clumsiness or difficulty catching objects
• Eye strain, headache, reading difficulty or fatigue
• In children, reduced vision in one eye due to amblyopia

In infants, brief eye crossing can occur in the first months of life as eye coordination develops. However, persistent misalignment, frequent eye turning, or any eye turn that continues beyond early infancy should be evaluated by an eye specialist. A white pupil reflection, drooping eyelid, unequal pupils or poor visual attention also needs prompt medical assessment.

Causes & Risk Factors

Strabismus usually develops when the muscles that move the eyes, the nerves that control them, or the brain systems that coordinate vision do not work together in the expected way. Each eye has six external muscles that control movement. Proper alignment requires precise coordination between these muscles and the visual processing centers of the brain.

In many children, strabismus is related to the development of binocular vision and may occur without a single identifiable cause. Some children have refractive errors, such as significant farsightedness, that make the eyes work harder to focus and can trigger inward turning. Amblyopia may occur together with strabismus, either as a result of eye misalignment or as a factor that makes one eye less able to maintain alignment.

Risk factors include a family history of strabismus or amblyopia, premature birth, low birth weight, developmental delay, cerebral palsy, Down syndrome, significant refractive error, previous eye injury and certain neurological or genetic conditions. Children with these risk factors benefit from timely vision screening and, when needed, ophthalmology evaluation.

In adults, strabismus may result from long-standing childhood strabismus that becomes more noticeable, thyroid eye disease, diabetes-related nerve problems, stroke, head injury, orbital disease, eye surgery, trauma or disorders affecting the nerves and muscles. Sudden-onset eye misalignment in an adult is assessed carefully because, although many causes are treatable, it can sometimes signal a medical or neurological condition that requires prompt attention.

Diagnosis

Strabismus is diagnosed through a comprehensive eye examination. The eye doctor asks about when the eye turn started, whether it is constant or intermittent, which direction the eye turns, whether double vision is present, and whether there is a family history of strabismus, amblyopia or significant refractive error. In children, observations from parents and photographs can be helpful.

The examination usually includes visual acuity testing appropriate for the person’s age, evaluation of eye alignment, eye movement testing and assessment of how the eyes work together. The doctor may use cover tests to measure how much the eye shifts when one eye is covered and uncovered. Special prisms may help quantify the angle of deviation.

Refraction is an important part of assessment because glasses may correct or reduce some types of strabismus. In children, eye drops are often used to relax focusing so the true prescription can be measured accurately. The doctor also examines the front and back of the eye to check eye health and rule out other conditions that may reduce vision or affect alignment.

Additional tests are not always needed, but they may be recommended when strabismus appears suddenly, is associated with double vision, follows trauma, or occurs with symptoms such as weakness, severe headache, eyelid drooping or abnormal pupil changes. In such situations, neurological evaluation, blood tests or imaging may be considered by the specialist to identify the underlying cause.

Treatment Options

Strabismus treatment aims to protect vision, improve eye alignment, support binocular vision when possible, reduce double vision and improve eye comfort. The right approach depends on age, type and size of the eye turn, visual acuity, refractive error, amblyopia, symptoms, general health and the underlying cause. A pediatric ophthalmologist, ophthalmologist or strabismus specialist decides the most appropriate plan after a full assessment.

Glasses or contact lenses may be recommended when refractive error contributes to the eye turn. Some children with focusing-related inward turning improve significantly with the correct prescription. Prism lenses may help selected patients, especially some adults with double vision, by shifting images so the eyes can work together more comfortably.

Amblyopia treatment may be needed if one eye has reduced vision. This can include patching the stronger eye or using other methods to encourage use of the weaker eye, under medical supervision. Orthoptic exercises or vision therapy may be useful for specific problems of eye coordination, particularly certain intermittent outward eye turns or convergence difficulty, but they are not suitable for every type of strabismus.

Some people may need procedures to improve alignment. Eye muscle surgery adjusts the position or tension of selected eye muscles so the eyes align more closely. In certain cases, injections into an eye muscle may be considered. Surgery can be performed in children or adults, but the goal and timing vary. Treatment may require follow-up, glasses, amblyopia therapy or more than one procedure over time. The specialist explains expected benefits, limitations and risks before any intervention.

Living With / Prognosis

The outlook for strabismus depends on the cause, age at diagnosis, degree of misalignment, presence of amblyopia and how well the eyes can develop or regain teamwork. Many children do well when strabismus is diagnosed early and treated consistently. Early treatment is especially important because the visual system develops rapidly in childhood, and untreated amblyopia may become harder to improve later.

Living with strabismus often involves regular follow-up. Eye alignment can change as a child grows, as refractive error changes, or after treatment. Adults may also need monitoring if strabismus is related to thyroid eye disease, nerve palsy, previous surgery or another medical condition. Keeping appointments helps the care team adjust glasses, monitor vision and decide whether further treatment is needed.

Practical support can make daily life easier. Children may need encouragement with patching or glasses, and parents can work with teachers if reading, sports or classroom tasks are affected. Adults with double vision may need temporary adaptations, such as avoiding driving until medically cleared, using prism correction if prescribed, or adjusting work tasks while treatment is planned.

Strabismus can affect self-confidence, social interaction and quality of life, especially when the eye turn is visible or symptoms interfere with activities. Patients should feel comfortable discussing both visual and appearance-related concerns with their doctor. Treatment decisions are individualized and may address function, comfort and alignment together.

When to See a Doctor

A doctor should assess any persistent eye misalignment in a child, even if the child seems to see well. Parents should seek evaluation if one eye frequently turns, if a child closes one eye, tilts the head, bumps into objects, has difficulty focusing, or shows signs of reduced vision. Routine childhood vision screening is also important because some children with amblyopia or refractive error may not show obvious symptoms.

Adults should arrange prompt medical assessment for new double vision or a new eye turn. Urgent evaluation is especially important if strabismus appears suddenly with severe headache, weakness, numbness, difficulty speaking, dizziness, eye pain, recent head injury, drooping eyelid, unequal pupils or loss of vision. These symptoms do not always indicate a serious condition, but they require careful examination.

Patients already diagnosed with strabismus should return to their doctor if symptoms worsen, double vision changes, glasses no longer help, a child refuses patching or glasses, or there are concerns after surgery or another procedure. Follow-up is part of safe care because treatment often needs adjustment over time.

International patients seeking evaluation may be cared for by multidisciplinary ophthalmology teams at Acibadem International, where JCI-accredited hospitals diagnose and treat strabismus in children and adults. As with any medical condition, the most appropriate care pathway should be decided after an in-person specialist examination.

Frequently asked questions

What is strabismus?

Strabismus is a condition in which the eyes are not aligned and do not point at the same target at the same time. One eye may turn inward, outward, upward or downward. It can occur in babies, children or adults and may be constant or intermittent.

Is strabismus the same as lazy eye?

Strabismus and lazy eye are related but not the same. Strabismus means the eyes are misaligned, while lazy eye, or amblyopia, means reduced vision in one eye because the brain has not developed normal visual input from that eye. Strabismus can cause amblyopia in children if it is not treated.

Can strabismus go away on its own?

Some brief eye misalignment can be seen in very young infants as eye coordination develops, but persistent or frequent strabismus should not be ignored. Many types require assessment and treatment to protect vision and eye teamwork. A qualified eye doctor can decide whether monitoring or active treatment is appropriate.

How is strabismus treated in children?

Treatment in children may include glasses, amblyopia therapy such as patching, eye exercises for selected cases, or eye muscle surgery. The plan depends on the type of strabismus, the child’s vision, refractive error and whether amblyopia is present. Early evaluation improves the chance of protecting normal visual development.

Why can strabismus start in adulthood?

Adult strabismus can be due to a childhood eye turn that changes over time, nerve problems, thyroid eye disease, diabetes-related complications, trauma, stroke, eye surgery or other medical conditions. New double vision or sudden misalignment should be assessed promptly. The treatment depends on the underlying cause and the person’s symptoms.

Does strabismus surgery restore normal vision?

Eye muscle surgery can improve eye alignment and may reduce double vision or improve the way the eyes work together in selected patients. It does not always restore normal binocular vision, especially if visual development was affected in childhood. The expected outcome varies, so the surgeon will discuss realistic goals before treatment.

When should a child be checked for crossed eyes?

A child should be checked if an eye turn is frequent, persistent, worsening or present beyond early infancy. Evaluation is also important if the child tilts the head, closes one eye, has poor tracking, seems clumsy or has a family history of strabismus or amblyopia. Parents do not need to wait for a child to complain, because young children may not notice a vision problem.

References

• American Academy of Ophthalmology
• American Association for Pediatric Ophthalmology and Strabismus
• National Eye Institute
• Royal College of Ophthalmologists
• Mayo Clinic

This article is for general information only and is not a substitute for professional medical advice. Please consult a qualified doctor about your individual situation.