section name header

Info


A. Epidemiologynavigator

  1. Affects 4% of children under 6 years
  2. 30-50% will develop secondary visual loss
  3. Early recognition and intervention allows binocular vision to develop
  4. Esotropic (deviating eye turns in) deviations most common
  5. Also called "Wandering Eye"
  6. May progress to amblyopia ("lazy eye") leading to vision loss

B. Classificationnavigator

  1. Hetertropia is misalignment of eyes that is always manifest
  2. Heterophoria is latent malalignment
  3. Prefixes indicate the direction of deviation
    1. Eso: inward
    2. Exo: outward
    3. Hyper: upward
    4. Hypo: downward

C. Pathogenesisnavigator

  1. Reflects inability of the eye's fusional mechanism to control eye deviation
  2. Unilateral hetertropia results in:
    1. Preference for the undeviated eye AND
    2. Loss of vision of the deviated eye
  3. Alternating bilateral hetertropia
    1. Normal vision development
    2. Because each eye is used in turn

D. Clinical Findingsnavigator

  1. May be asymptomatic or associated with squint
  2. Corneal Light Reflex Examination
    1. Requires minimal cooperation from the child
    2. Project a light source onto cornea of both eyes simultaneously
    3. If strabismus is present, the light will fall on different parts of each cornea
  3. Cover-Uncover Test
    1. Requires child's cooperation
    2. Patient stares at a distant object
    3. Examiner covers one eye and looks for movements of uncovered eye
    4. If no movement, then there is no misalignment of the eye
  4. Alternate-Cover Test
    1. Examiner rapidly covers and uncovers one eye like a wind-shield wiper
    2. If ocular deviation present, the eye rapidly moves as the cover is shifted to the other eye
  5. Pseudostrabismus
    1. Child falsely appears to have ocular misalignment or squint
    2. Appearance exaggerated in photographs
    3. Seen with flat broad nasal bridge, prominent epicanthial folds, or narrow intracanthial distance
    4. Corneal reflex and cover tests should differentiate true strabismus
    5. Facial asymmetries tend to lessen with growth
    6. No treatment needed

E. Non-Paralytic Strabismusnavigator

  1. Infantile Esotropia
    1. Present by 6 months
    2. Patching undeviated eye allows normal visual development in the other eye
    3. Glasses needed to correct far-sightedness
    4. Surgical realignment optimal before 2 ears to allow binocular vision to develop
  2. Accommodative Esotropia
    1. Occurs between 6 months and 7 years
    2. Most common form of strabismus
    3. Eye accommodates to correct a hyperopic or blurred image
    4. With large refractive errors, the amount of convergence may lead to esotropia
    5. Initially intermittent but can become constant
    6. Spectacle correction for hyperopic refractive error
    7. Reduces the need for accommodation and thus the stimulus for excessive convergence
    8. Bifocal spectacles sometimes needed for residual deviation at near fixation
    9. Eye muscle surgery needed for significant residual deviation
  3. Intermittent Exotropia
    1. Onset 6 months to 4 years
    2. Outward deviation of one eye when child is distance focusing
    3. Increased frequency with fatigue or illness
    4. Visual acuity and binocular vision
    5. Surgery needed for large or increasing frequency exotropia
  4. Constant Exotropia
    1. Rarely congenital
    2. Associated with neurologic disease or abnormalities of the bony orbit
    3. Includes association with a Couzon's syndrome
    4. Eye-patching to prevent visual impairment in deviated eye
    5. Surgery if deviation cosmetically significant

F. Paralytic Strabismus navigator

  1. Third Nerve Palsy
  2. Fourth Nerve Palsy
  3. Sixth Nerve Palsy

G. Third Nerve Palsynavigator

  1. Usually congenital in children
  2. Acquired form associations
    1. Intracranial neoplasm or aneurysm
    2. Inflammatory or infectious lesion
    3. Head trauma
    4. Post-viral syndromes
    5. Migraines
  3. Presentation
    1. Exotropia with downward deviation and ptosis
    2. Pupillary dilation may be present
  4. Surgical correction designed to redirect nerve fibers
  5. Botulinum toxin can be effective

H. Fourth Nerve Palsynavigator

  1. Congenital more common
  2. Acquired form associated with head trauma due to long intracranial course
  3. Weakness of superior oblique presents with hypertropia
  4. Head tilts to the shoulder opposite the affected eye to minimize double vision
  5. Eye surgery improves ocular alignment and eliminate head tilt

I. Sixth Nerve Palsynavigator

  1. Congenital deficit
  2. Rare condition
  3. Associated with Duone Retraction Syndrome
    1. Anomalous innervation causing a congenital disorder of ocular motility
  4. Acquired forms
    1. Self-resolving form seen in children following a febrile illness, upper respiratory infection
    2. Associated with ICP from hydrocephallus or intracranial mass
    3. Presents with markedly crossed eyes
    4. Ability to move affected eye laterally limited
    5. Head turns toward the palsied muscle to maintain binocular vision
    6. Surgical correction attempted

References navigator

  1. Donahue SP. 2007. NEJM. 356(10):1040 abstract
  2. Simon JW and Kaw P. 2001. Am Fam Phys. 64(4):623 abstract