II. Definitions
- Strabismus
- Eye misalignment in children
III. Epidemiology
- Accounts for 50% of Amblyopia (most common cause)
- Affects up to 4% of children in U.S.
IV. Types
- Esotropia or Esodeviation (Crossed Eyes, Convergent Strabismus)
- Both eyes turn inward
- Most common Strabismus cause, accounting for >50% of ocular deviations in children
- Typically present by age 18 to 36 months of age
- Accommodative Esotropia occurs when a child with uncorrected Farsightedness looks at a near object
- Congenital Esotropia is due to excessive convergence and is high risk for Amblyopia
- Exotropia or Exodeviation (Walleye, Divergent Strabismus)
- One eye turns outward while other eye faces forward
- Deviation most evident with distant Vision and therefore only occurs intermittently
- Typical onset in preschool aged children
- Parents often note changes on a bright day, or when children are tired or inattentive
- Eye deviates outward
- Child closes one eye
- Often children are able to self correct Exotropia with concentration
- Accommodative Exotropia occurs when a child with uncorrected Nearsightedness looks at a distant object
- Fourth Cranial Nerve palsy (superior oblique palsy)
- Eye rises when Head Tilted to side of palsy
- Findings
- Hypertropia (deviated eye turns up)
- Hypotropia (deviated eye turns down)
V. Signs: Screen at every well child check
- Test Specifically for Strabismus
- Only 50% children with Strabismus have obvious defect
VI. Signs: Organized by Strabismus type
- Manifest (Tropia): Strabismus that is always present
- Corneal Light Reflex
- Cover-Uncover exam
- Bruckner Test (Red Reflex)
- Fixation and following
- Intermittent Strabismus
- Healthy newborns develop alignment after age 4 weeks
- Intermittent exodeviation under 6 months
- Esodeviation much more likely to be pathologic
- Latent (Phoria): Present if binocular Vision blocked
- Only found when specifically tested
- Cover-Uncover exam
VII. Signs: Small-Angle Strabismus (Accommodative Esotropia)
- Identified with Cover Testing
- Seen in Farsighted toddlers
- Corrected with glasses or bifocals
- Abnormal use of accommodative convergence
- Normal reflex for near Vision
- Farsighted children use convergence all the time
VIII. Screening
-
General
- See testing above
- Photoscreening (picture of eyes and Red Reflex)
- May be used in future for mass screening
- Timing
- Screen frequently in first 3 years of life
- Example protocol: 8, 12, 18, 25, 31, 37 months of age
- Early diagnosis results in best outcome
- References
IX. Diagnosis: Immediate Ophthalmology Consult Indications
- Manifest (constant) deviation in any age
- Intermittent Exodeviation >6 months
- Intermittent Esodeviation >2 months
X. Diagnosis: Pitfalls - Pseudostrabismus
- Esotropia may be apparent despite normal alignment
- Iris appears to be surrounded by different white
-
Illusion of different amount white on each side of iris
- Flat Nasal Bridge
- Large epicanthal folds
- Differentiate from Strabismus with proper testing
- See Strabismus signs above
- Refer to Ophthalmology for any question of misalignment
XI. Management
- Early ophthalmology Consultation is critical
- Amblyopia treated prior to realignment surgery
- Accommodative Esotropia
- Farsightedness correction with bifocals
- Surgical correction if refractory
- Congenital Esotropia
- High risk for Amblyopia if not corrected by age 2 years old
- Onabotulinumtoxin A injection is an initial option in some cases
- Surgical Realignment of eyes
- Exotropia
- Surgical correction if constant, frequent or large exodeviation
- Hypertropia or Hypotropia
- Refer all cases to ophthalmology or pediatric neurology
XII. Prognosis
- Up to 40% of children with Strabismus will progress to Amblyopia
XIII. References
- Berson (1987) Ophthalmology Study Guide, AAO, p. 95-110
- Essman (1992) Am Fam Physician 46(4):1243-52 [PubMed]
- Mills (1999) Am Fam Physician 60(3):907-16 [PubMed]
- Reedy-Cooper (2023) Am Fam Physician 108(1): 40-50 [PubMed]
- Simon (2001) Am Fam Physician 64(4):623-8 [PubMed]