Strabismus, Esotropia, Convergent Strabismus, Crossed Eyes, Exotropia, Divergent Strabismus, Hypertropia, Hypotropia

  • Definitions
  1. Strabismus
    1. Eye misalignment in children
  • Epidemiology
  1. Accounts for 50% of Amblyopia (most common cause)
  2. Affects up to 4% of children in U.S.
  • Types
  1. Esotropia or Esodeviation (Crossed Eyes, Convergent Strabismus)
    1. Both eyes turn inward
    2. Most common Strabismus cause, accounting for >50% of ocular deviations in children
    3. Typically present by age 18 to 36 months of age
    4. Accommodative Esotropia occurs when a child with uncorrected Farsightedness looks at a near object
    5. Congenital Esotropia is due to excessive convergence and is high risk for Amblyopia
  2. Exotropia or Exodeviation (Walleye, Divergent Strabismus)
    1. One eye turns outward while other eye faces forward
    2. Deviation most evident with distant Vision and therefore only occurs intermittently
    3. Typical onset in preschool aged children
    4. Parents often note changes on a bright day, or when children are tired or inattentive
      1. Eye deviates outward
      2. Child closes one eye
    5. Often children are able to self correct Exotropia with concentration
    6. Accommodative Exotropia occurs when a child with uncorrected Nearsightedness looks at a distant object
  3. Fourth Cranial Nerve palsy (superior oblique palsy)
    1. Eye rises when Head Tilted to side of palsy
    2. Findings
      1. Hypertropia (deviated eye turns up)
      2. Hypotropia (deviated eye turns down)
  • Signs
  • Screen at every well child check
  1. Test Specifically for Strabismus
    1. Only 50% children with Strabismus have obvious defect
  • Signs
  • Organized by Strabismus type
  1. Manifest (Tropia): Strabismus that is always present
    1. Corneal Light Reflex
    2. Cover-Uncover exam
    3. Bruckner Test (Red Reflex)
    4. Fixation and following
  2. Intermittent Strabismus
    1. Healthy newborns develop alignment after age 4 weeks
    2. Intermittent exodeviation under 6 months
    3. Esodeviation much more likely to be pathologic
  3. Latent (Phoria): Present if binocular Vision blocked
    1. Only found when specifically tested
    2. Cover-Uncover exam
  • Signs
  • Small-Angle Strabismus (Accommodative Esotropia)
  1. Identified with Cover Testing
  2. Seen in Farsighted toddlers
  3. Corrected with glasses or bifocals
  4. Abnormal use of accommodative convergence
    1. Normal reflex for near Vision
    2. Farsighted children use convergence all the time
  • Screening
  1. General
    1. See testing above
    2. Photoscreening (picture of eyes and Red Reflex)
      1. May be used in future for mass screening
  2. Timing
    1. Screen frequently in first 3 years of life
    2. Example protocol: 8, 12, 18, 25, 31, 37 months of age
    3. Early diagnosis results in best outcome
  3. References
    1. Williams (2002) BMJ 324: 1549-51 [PubMed]
  • Diagnosis
  • Immediate Ophthalmology Consult Indications
  1. Manifest (constant) deviation in any age
  2. Intermittent Exodeviation >6 months
  3. Intermittent Esodeviation >2 months
  • Diagnosis
  • Pitfalls - Pseudostrabismus
  1. Esotropia may be apparent despite normal alignment
  2. Iris appears to be surrounded by different white
  3. Illusion of different amount white on each side of iris
    1. Flat Nasal Bridge
    2. Large epicanthal folds
  4. Differentiate from Strabismus with proper testing
    1. See Strabismus signs above
  5. Refer to Ophthalmology for any question of misalignment
  • Management
  1. Early ophthalmology Consultation is critical
  2. Amblyopia treated prior to realignment surgery
  3. Accommodative Esotropia
    1. Farsightedness correction with bifocals
    2. Surgical correction if refractory
  4. Congenital Esotropia
    1. High risk for Amblyopia if not corrected by age 2 years old
    2. Onabotulinumtoxin A injection is an initial option in some cases
    3. Surgical Realignment of eyes
      1. Repair under age 1 year offers best chance of near-normal binocular Vision
      2. Repair over age 1 to 2 years may result in significantly worse prognosis for binocular Vision
  5. Exotropia
    1. Surgical correction if constant, frequent or large exodeviation
  6. Hypertropia or Hypotropia
    1. Refer all cases to ophthalmology or pediatric neurology
  • Prognosis
  1. Up to 40% of children with Strabismus will progress to Amblyopia