Amblyopia vs Strabismus? Clarifying Common Pediatric Vision Disorders

Amblyopia and strabismus are two of the most common pediatric vision disorders. The two conditions share a number of similarities and are often confused with one another.

While the pediatric vision disorders may resemble each other on the surface, they feature distinct causes, symptoms, and treatments that patients and parents must be aware of. Knowing the key facts regarding amblyopia vs Strabismus arms parents with the knowledge to make informed choices about their child’s eye care.

Amblyopia is colloquially referred to as "lazy eye." It is a condition where vision in one eye has blurry, unfocused vision, while the other eye can see clearly. As amblyopia progresses, a child's brain begins to ignore the blurry eye in favor of the one with clear vision. This leads vision to further deteriorate in the weaker eye.

Amblyopia develops in early childhood, between birth and age 7, when the visual system is still maturing. As the condition worsens with time, parents should seek medical attention from an eye care specialist if they notice symptoms in their child.

Patients may recognize strabismus by its less formal name: crossed eyes. Strabismus is a condition where a patient's eyes are misaligned, typically one or both eyes turn in different directions.

Strabismus can vary in severity and can occur in any direction—turning inward (esotropia), outward (exotropia), upward (hypertropia), or downward (hypotropia). Strabismus may also be an ongoing issue or only happen occasionally in a condition called intermittent strabismus.

Strabismus is most commonly diagnosed in infancy or early childhood, but it can also develop in adults due to neurological or muscular issues. Patients with poor muscle control in their eyes and severe farsightedness are more likely to develop strabismus.

The condition arises when one eye has stronger visual acuity than the other. The brain will typically favor the eye with better vision, causing vision to further deteriorate in the weaker eye.

One of the common causes of amblyopia is a refractive error that is stronger in one eye than the other. One eye may be more nearsighted or farsighted than the other. In these cases the brain favors the dominant eye, leading to the development of amblyopia.

A type of amblyopia called “strabismic amblyopia” can occur when there is a misalignment between the eyes. This misalignment causes the brain to suppress the input from one eye to avoid double vision.

Visual obstructions such as cataracts, ptosis (a droopy eyelid), and other ocular conditions where light does not reach the retina can cause a form of amblyopia called “deprivation amblyopia.”

There is no single cause of strabismus. There are a variety of factors and underlying conditions which lead to strabismus. The condition may be caused by muscle imbalance or other neurological factors that disrupt the brain's ability to control eye movement.

Genetic factors can also play a role in the development of crossed eyes. Patients with a family history of strabismus are more likely to pass the condition down to their children. Certain medical conditions such as premature births, down syndrome, and cerebral palsy can increase the risk for a child to develop the condition.

Symptoms of amblyopia are typically difficult to spot. Patients may need to receive a comprehensive eye exam for doctors to detect symptoms and make a proper diagnosis.

The following symptoms may indicate a child has amblyopia and should see their doctor for further diagnosis:

• Clumsiness

• Poor depth perception

• Squinting or closing one eye to see better

• Difficulty with tasks requiring hand-eye coordination such as catching or throwing a ball

• Eye strain or fatigue with near work

Unlike amblyopia, the symptoms for strabismus are easier to observe. One of a patient's eyes will typically be turned in an abnormal direction.

Additionally, patients with strabismus may experience one or more of the following symptoms:

• Headaches or eye strain

• Decreased depth perception

• Difficulty focusing on a single object with both eyes

• Double vision

• Tilting the head to compensate for misalignment

• Frequent blinking or squinting

While amblyopia and strabismus are distinct medical conditions, they share a number of similarities which lead them to often be confused with one another. Both conditions are considered functional vision problems caused by the interplay between a patient’s eyes, brain, and visual pathways.

Both conditions also share key visually disruptive symptoms that may affect day to day activities. These include: headaches, double vision, difficulty focusing, and poor depth perception. The symptoms may overlap, explaining why it can be difficult to differentiate the two.

The colloquial names for amblyopia (lazy eye) and strabismus (crossed eyes) have also entered common vernacular, making them appear more similar in the minds of patients.

While amblyopia and strabismus share symptoms and similarities, they are distinct conditions with different underlying mechanisms and impacts on vision.

Strabismus is an issue with eye alignment in which a patient’s eyes fail to coordinate movement. In comparison, amblyopia is a problem with visual acuity where one eye suppresses input and has worse vision.

Additionally, strabismus is easier for an untrained eye to detect. It often does not require a visit to the eye doctor to spot the misalignment in the eyes associated with the condition. Comparatively, amblyopia is more difficult to detect. There are often no visible symptoms that show one eye has weaker vision than the other.

Even with these key differences, parents should take their children to the eye doctor to receive a formal diagnosis for both conditions.

Early detection is critical for both conditions, as the brain's plasticity during childhood makes it easier to correct these issues.

Both amblyopia and strabismus can be diagnosed through a comprehensive eye exam in which they observe a patient’s visual acuity, eye alignment, and refractive errors. During the exam the patient can determine which condition the child has and assess the best form of treatment.

For certain patients, eye doctors may conduct additional tests, depending on which condition they believe the patient has. For amblyopia doctors may use a cover-uncover test to assess how well each eye works independently and together. For strabismus doctors may use the Hirschberg test to evaluate corneal light reflex to detect misalignment.

The goal of amblyopia treatment is to strengthen the weaker eye and retrain the brain to use it effectively. Early intervention often leads to the best outcomes.

1. Corrective Lenses: Glasses or contact lenses are often prescribed to begin the process of improving alignment, focusing eyes, and correcting refractive errors.

2. Eye Patches: By covering the dominant eye with a patch, it can force the patient’s brain to use the weaker eye.

3. Atropine Drops: Has a similar effect to the patch. The drops blur vision in the stronger eye, and encourage the brain to rely on the weaker eye.

4. Vision Therapy: Exercises and activities to improve eye coordination, focus, and depth perception - especially in the weaker eye.

5. Surgical Interventions: Typically used as a last resort to remove obstructions caused by cataracts or drooping eyelids.

Strabismus treatment focuses on correcting the misalignment to improve binocular vision and prevent further complications.

1. Corrective lenses: Glasses or prism lenses that help align a patient’s eyes by adjusting refractive errors or redirecting light.

2. Vision therapy: Exercises designed to improve eye muscle coordination and strengthen neural pathways for alignment.

3. Surgical correction: Procedures used to adjust the length or position of the muscles controlling eye movement to work towards proper alignment.

4. Monitoring and Follow-Up: Strabismus often requires long-term management to ensure alignment stability and prevent recurrence.