Strabismus (Misaligned Eyes): Symptoms, Causes and Treatment

What is strabismus (misaligned eyes)?

Strabismus, commonly known as "misaligned eyes" or "crossed eyes," is a visual disorder characterized by the misalignment of one or both eyes. In a normal visual system, both eyes are aligned so that they point in the same direction and focus on the same object simultaneously, allowing the brain to create a single, coherent image.

However, in individuals with strabismus, the muscles that control eye movement do not work together properly. As a result, one eye may turn inward (esotropia), outward (exotropia), upward (hypertropia), or downward (hypotropia), while the other eye remains in its correct position. The misalignment can be constant or intermittent, depending on the type and severity of the condition.

Strabismus can occur at any age, but it is more commonly detected in infants, young children, and sometimes develops during adulthood. It can be caused by various factors, including problems with the eye muscles, issues with the nerves that control eye movement, or certain health conditions such as cerebral palsy or Down syndrome.

Apart from the visible misalignment of the eyes, individuals with strabismus may experience other visual symptoms, such as:

Double vision (diplopia): Due to the misalignment, the brain receives two different images from each eye, causing double vision.

Amblyopia (lazy eye): In some cases of strabismus, the brain may suppress or ignore the image from the misaligned eye, leading to poor vision in that eye. This is known as amblyopia.

Reduced depth perception: Properly aligned eyes work together to perceive depth, but misaligned eyes may struggle to provide accurate depth perception.

Strabismus is a treatable condition, and early detection is crucial for successful management. Treatment options may include:

Glasses: In some cases, prescription glasses can help correct refractive errors, which may contribute to the misalignment.

Patching therapy: In cases of amblyopia, patching the stronger eye may help strengthen the weaker eye and improve vision.

Vision therapy: This involves exercises and activities designed to improve eye coordination and strengthen eye muscles.

Surgery: In more severe cases or when other treatments are ineffective, eye muscle surgery may be recommended to align the eyes properly.

If you suspect that you or someone you know has strabismus, it is essential to seek an evaluation by an eye care professional, such as an ophthalmologist or optometrist, for proper diagnosis and appropriate treatment options. Early intervention can lead to better outcomes and prevent potential long-term vision problems.

What are the types of strabismus?

Strabismus, or misaligned eyes, can be classified into different types based on the direction of eye misalignment. The primary types of strabismus are:

● Esotropia: 

In esotropia, one or both eyes turn inward towards the nose. This is often referred to as "crossed eyes" or "convergent strabismus."

● Exotropia: 

Exotropia involves one or both eyes turning outward away from the nose. It is also known as "wall-eyed" or "divergent strabismus."

● Hypertropia: 

Hypertropia is characterized by one eye turning upward, while the other eye maintains its normal position.

● Hypotropia: 

In hypotropia, one eye turns downward while the other eye remains properly aligned.

These types of strabismus can further be classified into other subtypes based on factors such as onset, duration, and frequency of misalignment:

● Congenital strabismus:

 Present at birth or develops shortly after, this type is commonly detected in infants and young children.

● Acquired strabismus:

 Develops later in life, possibly due to trauma, health conditions, or neurological issues.

● Intermittent strabismus:

 The misalignment occurs periodically, and the eyes can align correctly at times.

● Constant strabismus:

 The misalignment is persistent, and the eyes remain in the same position most of the time.

● Alternating strabismus:

 The eye that misaligns switches between the two eyes.

● Unilateral strabismus:

 Only one eye is affected by the misalignment.

● Alternating bilateral strabismus: 

Both eyes take turns misaligning, but not at the same time.

It's important to note that the classification and specific types of strabismus may vary, and the treatment approach will depend on the type, severity, and underlying cause of the condition. An eye care professional, such as an ophthalmologist or optometrist, can provide a comprehensive evaluation and determine the most appropriate treatment plan for an individual with strabismus. Early detection and intervention are crucial to achieving the best possible outcomes for vision and eye coordination.

How common is strabismus?

Strabismus is a relatively common condition, especially in infants and young children. The prevalence of strabismus can vary based on different factors, including age, geographical location, and the criteria used for diagnosis. However, it is estimated that approximately 2% to 4% of the general population may have some form of strabismus.

Strabismus is often detected during early childhood, and it can occur in both males and females. It is one of the most common visual disorders in children. Some types of strabismus, such as esotropia, tend to be more prevalent than others.

The condition may also be more common in individuals with certain underlying health conditions, such as cerebral palsy or Down syndrome. Additionally, family history can play a role, as there may be a genetic component to the development of strabismus.

It's essential to diagnose and treat strabismus early, as the condition can lead to other visual problems, including amblyopia (lazy eye) and reduced depth perception. Regular eye exams by an eye care professional, especially for children, can help detect strabismus and other eye-related issues at an early stage, allowing for timely intervention and management. If you suspect that you or someone you know may have strabismus, it's advisable to seek an evaluation by an eye doctor for a proper diagnosis and appropriate treatment.

What are the symptoms of strabismus?

Strabismus, or misaligned eyes, can present with various symptoms, which can vary depending on the type and severity of the condition. Some common symptoms of strabismus include:

■ Visible misalignment:

 The most apparent symptom is the misalignment of one or both eyes. In some cases, the eyes may turn inward (esotropia), outward (exotropia), upward (hypertropia), or downward (hypotropia).

■ Eye discomfort: 

Strabismus may cause discomfort or strain in the affected eye or eyes.

■ Double vision:

 Misaligned eyes may result in the brain receiving two different images from each eye, leading to double vision (diplopia). To avoid confusion, the brain may suppress or ignore the image from one eye, which can also contribute to amblyopia (lazy eye).

■ Squinting or closing one eye:

 Some individuals with strabismus may squint or close one eye to avoid double vision or improve visual clarity.

■ Abnormal head posture:

 To compensate for the misalignment and improve vision, some people may adopt an abnormal head tilt or turn.

■ Poor depth perception:

 Properly aligned eyes work together to provide depth perception. However, individuals with strabismus may experience difficulties in accurately perceiving depth.

■ Eye fatigue: 

Keeping the eyes misaligned requires extra effort from the eye muscles, which can lead to eye fatigue or eye strain.

■ Impaired eye-hand coordination:

 Strabismus can affect eye-hand coordination and may impact tasks that require accurate visual targeting.

■ Social and psychological impacts:

 Strabismus, especially when it is noticeable, may affect a person's self-esteem and confidence, particularly in social situations.

It's important to note that young children may not be able to express or recognize these symptoms, making it crucial for parents, caregivers, or teachers to look for signs of strabismus in children. Early detection and treatment of strabismus are essential to prevent or address potential long-term vision problems and improve visual outcomes.

If you or someone you know experiences any of these symptoms or has concerns about eye alignment, it is essential to seek an evaluation by an eye care professional, such as an ophthalmologist or optometrist, for a proper diagnosis and appropriate treatment.

When do the symptoms of strabismus appear?

The symptoms of strabismus, or misaligned eyes, can appear at different times depending on the type and underlying cause of the condition. In some cases, the symptoms may be present from birth or shortly after, while in others, they may develop later in life. The timing of symptom onset can be categorized as follows:

● Congenital strabismus: 

This type of strabismus is present at birth or develops within the first few months of life. It is often noticed in infants as they start to fixate on objects and follow movements with their eyes. Congenital strabismus can be constant or intermittent and is usually associated with a family history of the condition.

● Early childhood onset: 

Strabismus may also develop during early childhood, typically before the age of 6 years. Children with early-onset strabismus may exhibit signs such as squinting, eye rubbing, head tilting, or abnormal head postures to compensate for the misalignment.

● Acquired strabismus: 

This type of strabismus develops later in life, after the age of 6 years. Acquired strabismus can be caused by various factors, including trauma, eye injury, neurological conditions, or certain health problems.

It's important to note that strabismus may not always be apparent, especially in young children. In some cases, the misalignment may only be noticed when the child is fatigued, ill, or looking at objects up close. Additionally, strabismus can be intermittent, meaning the eyes may appear aligned at times and misaligned at other times, making it more challenging to detect.

Early detection and intervention are crucial for the successful management of strabismus, as prompt treatment can help prevent complications such as amblyopia (lazy eye) and improve the chances of achieving better eye alignment and visual outcomes. Regular eye examinations by an eye care professional, especially during early childhood, can help identify strabismus and other vision-related issues at an early stage. If you suspect that you or someone you know may have strabismus, it is advisable to seek an evaluation by an eye doctor for a proper diagnosis and appropriate treatment.

What causes strabismus?

Strabismus, or misaligned eyes, can be caused by various factors, and the exact cause can vary from person to person. It often results from a disruption in the normal coordination of the eye muscles, which are responsible for controlling the movement of the eyes. Some common causes of strabismus include:

■ Muscle Imbalance: 

The most common cause of strabismus is an imbalance in the muscles that control eye movement. If one or more eye muscles are weaker or stronger than their counterparts in the other eye, it can lead to misalignment.

■ Nerve Issues:

 Problems with the nerves that transmit signals from the brain to the eye muscles can also cause strabismus. If the signals are not properly coordinated, the eyes may not move in sync, leading to misalignment.

■ Refractive Errors:

 Uncorrected refractive errors, such as nearsightedness (myopia), farsightedness (hyperopia), or astigmatism, can sometimes contribute to strabismus, especially in individuals who have a significant difference in prescription between their eyes.

■ Genetics:

 Strabismus can have a genetic component, meaning it may run in families. If a parent or a close family member has strabismus, there is a higher risk of other family members developing the condition.

■ Health Conditions:

 Certain medical conditions, such as cerebral palsy, Down syndrome, or brain tumors, can be associated with strabismus due to their impact on the nervous system and eye muscles.

■ Trauma or Injury: 

Head injuries or trauma to the eye area can damage the eye muscles or nerves, leading to strabismus.

■ Vision Loss:

 In some cases, vision loss in one eye due to other eye conditions or injuries can cause the brain to suppress the input from that eye, leading to strabismus.

It's important to note that not all cases of strabismus have a clear or identifiable cause. Strabismus can be present at birth (congenital) or develop later in life (acquired). Early detection and appropriate treatment are crucial to prevent complications such as amblyopia (lazy eye) and to improve the alignment and coordination of the eyes.

If you or someone you know has symptoms of strabismus, it is essential to seek an evaluation by an eye care professional, such as an ophthalmologist or optometrist, for a thorough examination and diagnosis. The specific cause of strabismus in each individual can help guide the appropriate treatment plan.

What are the complications of strabismus?

Strabismus, if left untreated or inadequately managed, can lead to several complications that can affect vision and overall eye health. Some of the common complications associated with strabismus include:

● Amblyopia (Lazy Eye): 

Amblyopia occurs when the brain suppresses or ignores the input from one eye to avoid confusion caused by the misalignment. As a result, the brain relies more on the input from the stronger eye, leading to reduced vision in the weaker eye. If amblyopia is not addressed during early childhood, it can result in permanent vision loss in the affected eye.

● Reduced Depth Perception: 

Properly aligned eyes work together to provide binocular vision, which allows accurate depth perception. Strabismus disrupts binocular vision, causing difficulties in accurately perceiving depth and spatial relationships.

● Eye Strain and Fatigue: 

Misaligned eyes require extra effort from the eye muscles to maintain alignment or suppress the input from one eye. This constant effort can lead to eye strain, discomfort, and fatigue.

● Squinting and Head Postures: 

Individuals with strabismus may adopt abnormal head postures or squint to improve vision and reduce double vision, which can cause discomfort and lead to social and self-esteem issues.

● Abnormal Development of Vision Pathways:

 In early childhood, the visual system is still developing. Untreated strabismus can lead to abnormal development of the visual pathways, which may be challenging to correct later in life, even with treatment.

● Psychosocial Effects:

 Strabismus, especially when noticeable, can have a significant impact on a person's self-esteem and confidence, leading to social and emotional challenges.

● Risk of Accidents and Falls: 

Reduced depth perception and impaired visual coordination may increase the risk of accidents and falls, especially in unfamiliar or challenging environments.

● Permanent Eye Misalignment:

 In some cases, without intervention, the misalignment of the eyes can become fixed and more challenging to treat.

It is essential to address strabismus as early as possible to prevent or minimize these complications. Treatment options for strabismus may include glasses, eye exercises (vision therapy), patching therapy, or eye muscle surgery, depending on the type and severity of the condition. Regular eye examinations by an eye care professional, especially during childhood, can help detect strabismus and other vision-related issues early, allowing for timely intervention and better visual outcomes. If you or someone you know has strabismus, it is important to seek an evaluation by an eye doctor for proper diagnosis and appropriate treatment.

How is strabismus diagnosed?

Diagnosing strabismus involves a comprehensive eye examination conducted by an eye care professional, such as an ophthalmologist or optometrist. The evaluation includes various tests and assessments to determine the presence of misaligned eyes and identify the type and severity of the condition. The diagnostic process typically includes the following steps:

■ Case History: 

The eye care professional will begin by asking about the patient's medical history, including any family history of eye conditions or strabismus, and inquire about any symptoms or visual complaints.

■ Visual Acuity Testing:

 This test measures the clarity of vision in each eye using an eye chart. It helps identify any significant differences in vision between the two eyes and assesses for potential amblyopia (lazy eye).

■ Cover Test: 

The cover test is a simple examination used to detect the presence and magnitude of strabismus. The patient is asked to focus on a specific target while the eye care professional covers one eye and then quickly uncovers it to observe any eye movement to re-fixate on the target. This test can help identify both manifest (visible) and latent (intermittent) strabismus.

■ Ocular Motility Testing:

 This evaluation assesses the range of eye movements and the coordination of eye muscles. It can help identify any limitations or abnormalities in eye movement.

■ Refraction: 

Refraction is performed to determine any refractive errors (e.g., myopia, hyperopia, astigmatism) that may contribute to the misalignment or affect visual acuity.

■ Stereopsis Test: 

Stereopsis is the ability to perceive depth and 3D vision. This test checks for binocular vision and depth perception.

■ Examination of Eye Alignment:

 The eye care professional will visually assess the alignment of the eyes in different positions of gaze and under various conditions of fixation.

■ Cycloplegic Refraction (for children):

 In some cases, especially with children, a cycloplegic refraction may be performed. This involves using eye drops to temporarily paralyze the eye's focusing mechanism, allowing for a more accurate measurement of the refractive error.

■ Additional Tests: 

Depending on the individual case, additional tests or imaging studies, such as funduscopy, visual field testing, or imaging of the eye muscles, may be performed to further evaluate the condition.

Once the diagnosis of strabismus is confirmed, the eye care professional will determine the type, severity, and underlying cause of the misalignment. This information helps guide the appropriate treatment plan, which may include glasses, vision therapy, patching therapy, and in some cases, eye muscle surgery. Early detection and timely intervention are crucial for the successful management of strabismus and to prevent complications such as amblyopia and permanent vision problems.

How is strabismus treated?

Strabismus, or misaligned eyes, can be treated through various approaches, depending on the type and severity of the condition. The primary goal of treatment is to improve eye alignment, restore binocular vision, and prevent or address complications such as amblyopia (lazy eye). The treatment options for strabismus include:

● Glasses: 

Prescription glasses may be prescribed to correct any refractive errors (e.g., nearsightedness, farsightedness, astigmatism) that could be contributing to the misalignment.

● Patching Therapy: 

Patching therapy is used to treat amblyopia (lazy eye) that may result from strabismus. By covering the stronger eye with an eye patch, the weaker eye is encouraged to strengthen and improve vision.

● Vision Therapy (Orthoptics): 

Vision therapy involves a series of exercises and activities designed to improve eye coordination, strengthen eye muscles, and promote binocular vision. It is often used in cases of intermittent or mild strabismus.

● Prisms: 

In some cases, special prism lenses may be prescribed to help alleviate double vision and improve visual comfort. Prisms can shift the image seen by one eye, making it easier for the brain to fuse the two images together.

● Botulinum Toxin (Botox) Injection:

 In certain cases of strabismus, particularly when the condition is caused by overactive eye muscles, botulinum toxin injections may be used to weaken specific muscles temporarily, helping to realign the eyes.

● Eye Muscle Surgery: 

Eye muscle surgery is considered when other treatments have not been successful or in cases of constant or severe strabismus. During the surgery, the eye muscles are adjusted to improve eye alignment.

The choice of treatment will depend on several factors, including the type and severity of strabismus, the presence of amblyopia, the patient's age, and individual preferences. Early intervention is crucial, especially in children, to prevent long-term vision problems and achieve the best possible outcomes.

The treatment of strabismus is typically managed by an ophthalmologist or an eye care professional with expertise in treating eye alignment issues. The specific treatment plan will be tailored to each individual's needs and may involve a combination of different therapies. Regular follow-up appointments are essential to monitor progress and make any necessary adjustments to the treatment plan. If you or someone you know has strabismus, it's essential to seek guidance from an eye care specialist for a thorough evaluation and appropriate treatment.

Can strabismus be prevented?

Strabismus, in some cases, can be prevented or its severity reduced through early detection and appropriate intervention. While not all cases of strabismus can be entirely prevented, there are certain steps that can be taken to increase the likelihood of detecting and addressing the condition early, which can improve the chances of successful treatment and minimize potential complications:

■ Regular Eye Examinations:

 Routine eye exams are essential, especially during early childhood. Pediatricians may perform basic vision screenings, but a comprehensive eye examination by an eye care professional (ophthalmologist or optometrist) is recommended, starting from infancy and continuing throughout childhood.

■ Vision Screening in Schools:

 Schools often conduct vision screenings to identify potential vision problems, including strabismus. However, it's important to remember that a comprehensive eye examination by an eye care professional is still necessary to confirm any suspected issues.

■ Early Intervention for Amblyopia: 

Amblyopia, or lazy eye, often occurs alongside strabismus. Promptly treating amblyopia with patching therapy and/or vision therapy can help improve visual acuity and prevent permanent vision loss in the weaker eye.

■ Addressing Refractive Errors: 

Correcting any refractive errors (nearsightedness, farsightedness, astigmatism) with prescription glasses or contact lenses may help prevent or reduce the development of strabismus.

■ Timely Treatment for Eye Injuries or Conditions: 

Promptly seeking medical attention for eye injuries or health conditions that affect the eyes can help prevent strabismus or other complications.

■ Monitoring Eye Development:

 Parents and caregivers should pay attention to their child's visual behavior, including eye alignment and how they track objects. If any concerns arise, seeking an eye examination is essential.

■ Genetic Counseling:

 If there is a family history of strabismus or other eye conditions, genetic counseling may provide useful information about the potential risk for developing strabismus in other family members.

While these steps can increase the chances of early detection and intervention, it's important to recognize that not all cases of strabismus can be prevented. Some cases may have no apparent cause or may develop later in life due to other factors. Regular eye care and vigilance are essential in promoting good eye health and addressing vision issues as early as possible. If you suspect that you or someone you know may have strabismus, it's crucial to seek an evaluation by an eye care professional for a proper diagnosis and appropriate treatment.

What is the prognosis (outlook) for strabismus?

The prognosis for strabismus, or misaligned eyes, can vary depending on several factors, including the type, severity, and underlying cause of the condition, as well as the age at which treatment begins. Early detection and timely intervention generally lead to better outcomes and improved long-term vision.

With appropriate and timely treatment, many cases of strabismus can be successfully managed, and the eyes can be realigned to work together more effectively. The prognosis is generally better when the following conditions are met:

● Early Intervention: 

Strabismus detected and treated early in childhood, especially before the age of 6 years, tends to have a better prognosis. Early treatment can help prevent complications such as amblyopia (lazy eye) and improve the chances of achieving binocular vision.

● Compliance with Treatment: 

Consistent adherence to the prescribed treatment plan, including patching therapy, vision therapy exercises, or wearing corrective glasses, is essential for successful outcomes.

● Type of Strabismus: 

Some types of strabismus may respond more favorably to treatment than others. The success of treatment can depend on the direction and degree of eye misalignment.

● Cause of Strabismus: 

If the strabismus is secondary to a correctable factor, such as a refractive error or eye muscle imbalance, addressing the underlying cause can lead to better alignment.

● Combination of Treatments:

 In some cases, a combination of treatments, such as glasses, patching therapy, and vision therapy, may be required to achieve the best results.

● Eye Muscle Surgery:

 When indicated and performed by a skilled ophthalmologist, eye muscle surgery can significantly improve eye alignment and lead to a successful visual outcome.

It's important to note that not all cases of strabismus can be completely corrected, and some individuals may still experience residual misalignment even after treatment. However, the goal of treatment is to maximize visual function, improve eye alignment, and prevent complications.

In cases where strabismus is detected later in life or left untreated for an extended period, achieving complete eye alignment and restoring binocular vision may be more challenging. However, even in such cases, treatment can still help improve visual function, comfort, and quality of life.

Regular follow-up visits with an eye care professional are essential to monitor progress, make any necessary adjustments to the treatment plan, and address any changes in eye alignment or visual function over time. If you or someone you know has strabismus, seeking early evaluation and appropriate treatment can lead to better outcomes and overall eye health.

When should I see my healthcare provider?

You should see your healthcare provider, preferably an eye care professional like an ophthalmologist or optometrist, if you experience any of the following concerning signs or symptoms related to your eyes:

■ Eye Misalignment: 

If you notice that your eyes are not properly aligned or appear crossed, turned inward, outward, upward, or downward, you should seek evaluation.

■ Double Vision:

 If you see double images or experience double vision, especially when looking at a single object, it could be a sign of strabismus or other eye issues.

■ Eye Strain or Discomfort: 

Frequent eye strain, discomfort, or headaches, especially after reading or focusing on objects for an extended period, should be evaluated.

■ Squinting or Closing One Eye: 

If you find yourself squinting or frequently closing one eye to improve vision or reduce discomfort, it may indicate an underlying eye problem.

■ Abnormal Head Posture: 

Adopting an unusual head tilt or turn to see better or align your eyes may be a sign of eye misalignment.

■ Vision Changes: 

Any sudden or gradual changes in vision, such as blurred vision or difficulty seeing clearly, warrant examination.

■ Eye Injury or Trauma:

 If you have experienced an eye injury or trauma, seeking prompt medical attention is crucial.

■ Family History of Strabismus or Eye Conditions:

 If you have a family history of strabismus or other eye conditions, it's essential to inform your eye care provider during your eye examination.

■ Routine Eye Exams: 

Regular eye examinations are essential, especially for children, to detect vision problems and eye conditions early.

Remember that early detection and timely intervention are crucial for managing eye conditions effectively and achieving better outcomes. If you suspect that you or someone you know may have strabismus or other eye-related issues, schedule an appointment with an eye care professional for a comprehensive eye examination and proper diagnosis. It's always better to address eye health concerns as soon as possible to prevent potential complications and ensure good visual function and overall eye health.