INTRODUCTION TO STRABISMUS

EPIDEMIOLOGY

2-4% of the general population

National Health Survey 1971-1972

overall, 1-74 year olds, 3.7% prevalence

esotropia 1.2%

exotropia 2.1%

hypertropia 0.4%

 

STRABISMUS MYTHOLOGY

  1. strabismus will go away
  2. strabismus is caused by weak muscles
  3. most children are strabismic for a time
  4. surgery is the only treatment option
  5. surgery is never a treatment option
  6. strabismic amblyopia cannot be treated after age 6

 

ETIOLOGIES OF STRABISMUS

CAUSE
PROPONENT
ACCOMMODATION
DONDERS / LANDOLT

PARETIC MUSCLE
SNELLEN
MECHANICAL RESTRICTIONS
BIELSCHOWSKY
LACK OF SENSORY FUSION ABILITY
WORTH
DEFICIT IN OPTOMOTOR REFLEXES
CHAVESSE / KEINER
ANOMALY OF CON / DI-VERGENCE
DUANE
NEARPOINT DISORDER
SKEFFINGTON
PSYCHOLOGICAL
MANY

STRABISMUS HISTORY

  1. HPI - history of the present illness
    1. clinical course
    2. previous diagnoses and treatments
      1. examinations
      2. refractive correction
      3. treatment of amblyopia
      4. surgery
      5. vision therapy
  2. age of onset, aka duration of condition
  3. type of onset
  4. past family history

 

STRABISMUS DIAGNOSIS

  1. observation
  2. Hirschberg
  3. cover test
  4. cover test
  5. cover test
  6. cover test
  7. cover test
  8. cover test
  9. cover test
  10. cover test
  11. cover test
  12. occasionally a specialized test for a very small angle esotropia

 

OBJECTIVES OF STRABISMUS DIAGNOSIS

Is strabismus present?

If so:
  1. frequency
  2. eye dominance
  3. magnitude
  4. consistency
  5. distance vs near
  6. gaze direction
  7. amblyopia
  8. anomalous correspondence
  9. suppression

What is the management decision?

 

CLASSIFICATION OF STRABISMUS

 

  • direction
    • horizontal
    • vertical
    • cyclo
  •  
  • laterality
    • unilateral
    • alternating
  •  
  • frequency
    • constant
    • intermittent
    • periodic
    • cyclic
  •  
  • fixation distance
    • distance
    • near point
    • intermediate
  •  
  • magnitude
    • objective angle
      • actual amount of eye turn
    • subjective angle
      • how much the patient thinks the eye is turned
      • is usually smaller, if different from objective angle
    • a significant difference indicates ARC

     

     

  •  
  • comitancy
    • comitant
    • noncomitant
      • primary angle
        • strabismic angle with "good" eye fixating
      • secondary angle
        • strabismic angle with the "paretic" eye fixating
  •  
  • time of onset
    • congenital
    • infantile
    • childhood
    • acquired