What Is the Cause of Cross-Eyes?

Reviewed on 1/23/2023
Cause of Cross-Eyes
Cross-eyes can distort your vision and impair your ability to read or conduct daily activities.

Cross-eyes or squint are the common names for the medical condition strabismus. Cross-eye causes the eyes to not align properly when looking at an object or image, resulting in double vision (binocular vision).

Strabismus in children can be caused by inadequate development of muscles or nerves. If it develops in the first few months of life, it is mainly caused by the brain not managing eye alignment correctly.

Causes of cross-eye

  • Abnormalities in the eye muscles
    • Each eye has six muscles that control its movement.
    • To concentrate on one thing at a time, all 12 muscles in both eyes must work together.
    • However, the muscles may not always coordinate adequately, leading one eye to move in an odd direction.
  • Damage to the nerves that control the eye muscles
    • Cross-eye can be caused by an injury or deficiency in either of the three cranial nerves.
    • Dysfunctional nerves cannot move the muscles as needed, which leads to cross-eye.
  • Neurological issues
    • Cross-eye can be caused by a malfunction with the control centers in the brain that instruct the nerves and eye muscles.

Risk factors for cross-eyes

What is cross-eye?

Cross-eye or strabismus is a medical word for misaligned eyes; the eyes do not point in the same direction at the same time.

Although many adults have strabismus, it is most typically observed in children.

Each eye may alternate between gazing straight ahead and rotating in some circumstances. As a result, the eyes do not cooperate. Instead of one clear image, each eye sees a separate image (binocular vision).

Cross-eyes can distort your vision and impair your ability to read or conduct daily activities. According to statistics, nearly 5 in 100 children develop cross-eye.

Common types of cross-eyes

  • Small angle: Minor eye misalignment.
  • Large angle: Severe eye misalignment.
  • Esotropia: An inward twisting of the eye.
    • Congenital strabismus
    • Infantile strabismus
    • Accommodative strabismus
    • Amblyopic strabismus
  • Exotropia: An outward deviation of the eye.
    • Steady strabismus
    • Intermittent strabismus
    • Alternating strabismus
  • Hypertropia: An upward deviation of the eye.
  • Duane syndrome: Characterized by difficulty moving the eyes laterally and by ocular retraction.

What are the symptoms of cross-eyes?

The most obvious symptom of cross-eyes is eye misalignment, which can lead to amblyopia and visual impairments.

Common symptoms of cross-eyes include:

Because it impairs the ability to make proper eye contact with others, cross-eyes may cause severe emotional stress in children.

Strabismus could only be visible in certain children when they are sleepy or ill or when they are looking in a specific direction.

Some signs, however, could not be detected until the child is old enough to express symptoms.

  • Double or blurred vision
  • Difficulty reading

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How is cross-eye diagnosed?

A comprehensive eye examination is a must to diagnose and treat cross-eyes. The doctor notes the thorough history related to the cross-eye and conducts a series of tests to evaluate vision and eye coordination.

  • Visual acuity
    • Measures the ability of the eye to detect forms and features of things at a particular distance.
    • It is crucial to test visual acuity consistently to detect changes in vision.
    • Both eyes are tested one after the other.
  • Refractive error
    • The doctor checks vision and detects any possible refractory error.
    • A powered lens will be prescribed to correct the refractory error.
  • Eye health
    • A split microscope could be used to check for the eyes' health.

How is cross-eye treated?

All children with newly diagnosed cross-eye should undergo a thorough evaluation of visual function by an ophthalmologist.

Treatment options to correct cross-eye include:

  • Visual rehabilitation: Various visual rehabilitation methods help with correcting the cross-eye, but they depend on the type of ocular deviation involved and whether the cross-eye is primary or secondary.
  • Glasses or lenses:
    • Most common nonsurgical treatment.
    • Correction of refractive errors in one or both eyes using glasses or contact lenses. Prisms in spectacles could be used.
    • Amblyopia is treated with patching or atropine drops.
    • Ocular alignment surgery is routinely advised and is generally an outpatient procedure with minimal post-operative pain.
  • Behavioral eye exercises: Exercise for the muscles that govern eye movement can occasionally help the eyes perform better together.
  • Surgery:
    • Repositions the muscles that regulate eye movement for the eyes to line up appropriately.
    • Could be advised if glasses are ineffective.
    • Can be performed as an outpatient procedure and causes minimal post-operative pain.
    • Strabismus surgery is done to change the aesthetics of the eye and help restore binocular vision.
  • Injectable botulinum:
    • Administered directly into the eye muscles. They weaken the muscles, allowing the eyes to line up better.
    • However, the impact generally lasts less than three months.

The primary treatment aims are to avoid amblyopia and establish binocular vision with functional depth perception (stereopsis), and the secondary goal is to improve aesthetics.

What is amblyopia?

Cross-eye is one of the most common causes of amblyopia. Amblyopia (impaired vision or low visual acuity) is caused when one eye does not see properly. This prevents the circuits in the brain that serve that eye from acquiring vision properly. Amblyopia is also called lazy eye.

Amblyopia cannot be treated with glasses because the problem is not with the eye's focus, but with the pathways in the brain that serve the eye. It is a new condition induced by cross-eye.

The treatment for amblyopia is to avoid cross-eyes early enough to allow the brain's visual processing sections to develop.

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References
Image Source: iStock image

Crossed-Eyes (Strabismus). https://www.stanfordchildrens.org/en/topic/default?id=crossed-eyes-strabismus-90-P02109

Strabismus. https://www.hopkinsmedicine.org/health/conditions-and-diseases/strabismus

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