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  • Writer's pictureAtanas Bogoev M.D. and Maria Cholakova

Strabismus or Lazy Eye? Differences and Similarities.

Is it strabismus or lazy eye - how to tell them apart? If you've asked yourself this question, you are in the right place. Amblyopia (lazy eye) and strabismus (squint/crossed eyes), though related, are two very distinct conditions. But what's happening quite often is people confusing the both and the connection between them.

With this article, we want to help our readers understand the differences and similarities between the two. Because that's essential for accurate diagnosis, treatment, and management. Especially in children, where these eye conditions are most prominent.

Get ready to address common questions, misconceptions, and relevant topics about strabismus and lazy eye!

Strabismus vs Lazy Eye

While strabismus and lazy eye are interconnected, they are NOT identical eye conditions. Strabismus involves the misalignment of the eyes. Whereas lazy eye involves partial vision loss in one eye.

What is Amblyopia (Lazy Eye)?

Lazy eye, medically termed amblyopia, is decreased vision in one eye due to abnormal visual development during childhood. It often occurs when one eye receives weaker visual signals than the other, leading to the brain favoring the stronger eye and neglecting the weaker one.

The telling signs for lazy eye are:

  • Poor depth perception

  • Difficulty judging distances

  • Persistent eye rubbing or blinking

  • Complaints of blurry or fuzzy vision in one eye

  • One eye sees more clearly than the other

  • Excessive clumsiness or bumping into objects

There are different types of lazy eye, including strabismic amblyopia (associated with strabismus), deprivation amblyopia (usually caused by congenital clouding of the lens - cataract or corneal scars), refractive amblyopia (caused by unequal refractive errors between the eyes). Treatment usually includes covering the stronger eye with an eye patch.

child with lazy eye

What is Strabismus?

Strabismus, also known as crossed eyes or squint, is a visual misalignment of the eyes. Strabismus can result from problems with eye muscles, neurological issues, refractive errors, or trauma. The misalignment may have genetic predispositions.

The warning signs of strabismus are:

  • Eyes that appear misaligned, crossed, or wander in different directions

  • Squinting or closing one eye to focus

  • Tilting or turning the head to see better

  • Complaints of double vision

There are several types of strabismus, including esotropia (inward deviation), exotropia (outward deviation), hypertropia (upward deviation), and hypotropia (downward deviation).

types of strabismus

Does Strabismus Cause Lazy Eye or Vice Versa?

Strabismus can lead to amblyopia if not treated promptly, as the brain may suppress the input from the misaligned eye.

Amblyopia, on the other hand, can trigger crossed eyes if the weaker eye deviates due to a lack of visual stimulation. So it's less common but still possible to have strabismus due to lazy eye.

Can You Have Lazy Eye Without Strabismus?

Yes, it is possible to have lazy eye without strabismus. Amblyopia can result from various factors, including unequal refractive errors between the eyes or other visual abnormalities, without the presence of eye misalignment.

Is Strabismus Always Due to Lazy Eye?

Not necessarily. While strabismus can lead to lazy eye, it can also occur independently. Strabismus can stem from issues with eye muscles, neurological conditions, or other factors unrelated to low vision in one eye.

Can You Get Lazy Eye After Strabismus Surgery?

In some cases, lazy eye may persist or develop after strabismus surgery. That happens if visual deprivation is not adequately addressed before or during the procedure. Proper preoperative evaluation and postoperative management minimize the risk of lazy eye after strabismus surgery.

Differences and Similarities

Differences Between Strabismus and Lazy Eye

The first and most prominent difference is by definition. Strabismus means one or both eyes deviate from their normal position. While lazy eye refers to impaired vision in one eye.

The primary symptom of strabismus is the noticeable crossed eyes (constant or intermittent). While lazy eye manifests as a loss of vision in one eye, which may not always be visibly apparent without an eye exam.

Another notable difference between strabismus and lazy eye is the cause. Strabismus results from eye muscle problems, neurological conditions, refractive errors, trauma, or other factors affecting eye alignment. Lazy eye occurs due to unequal visual input between the eyes during critical periods of visual development.

Treatment for crossed eyes often focuses on realigning the eyes. Yet, treatment for lazy eye aims to improve vision in the weaker eye by encouraging its use through techniques obstructing the stronger eye.

Last but not least, while strabismus affects binocular vision and depth perception, patients may still have relatively normal visual acuity in each eye. But lazy eye directly impacts eyesight in one eye.

child with strabismus
A child with strabismus (crossed eyes)

Similarities Between Strabismus and Lazy Eye

The first similarity between strabismus and lazy eye is developmental onset. Both strabismus and lazy eye often develop in childhood (although they can occur at any age).

Left untreated, both conditions can have complications, such as permanent vision loss, low depth perception, and other vision-related problems.

Treatment for both may require a multidisciplinary approach. The approach involves eye doctors and sometimes pediatricians or neurologists, depending on the cause and associated conditions.

Treatment Options

Routine eye exams make a difference for individuals in the risk groups. During the appointment, the eye doctor can assess a patient's visual acuity, eye alignment, and overall eye health, which is key to catching strabismus or lazy eye early.

Strabismus Treatment

  • Glasses or Contact Lenses (if the misalignment is due to refractive errors)

  • Prism Lenses (special eyeglass lenses that redirect the light entering the eyes, thereby reducing double vision and improving alignment)

  • Surgery (adjusting the position of the eye muscles surgically)

Lazy Eye Treatment

  • Eye Patching (covering the stronger eye with a patch)

  • Atropine Eye Drops (used to blur the vision in the stronger eye, typically applied to the stronger eye once a day)

  • Bangerter Filters (translucent filters applied to the lenses of glasses to blur vision in the stronger eye)

  • Surgery (usually in the cases of amblyopia caused by congenital cataracts)

Early detection and timely treatment help patients achieve optimal outcomes. In children, the visual system is more adaptable during developmental stages, so don't wait if you notice any warning signs in your child.


  • Amblyopia, Ochno Zdrave (bulgarian health website)

Checked by Atanas Bogoev, MD.

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