Exotropia

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General Information

  • 2/3 of infants exhibit mild exotropia in the first months of life

Congenital Exotropia

  • Rare
  • Often present at birth
  • Findings: normal refraction, large and constant angle of strabismus (usually > 35 prism diopters), amblyopia is rare
  • Associations:
    • Dissociated vertical deviation (DVD)
    • Inferior or superior oblique muscle overaction
  • May spontaneously regress within 6 months; otherwise, surgery is indicated

Divergence Excess

  • Exodeviation at least 10 prism diopters greater for distance than near

Convergence Insufficiency

  • Typically seen in individuals with excessive near vision demands, e.g., students
  • Findings: reduced near point of convergence, independent of any heterophoria
  • Treatment: orthoptic exercises to normalise the near point and maximise fusion amplitudes
    • If not regressing within a few weeks, consider base-in prisms

Convergence Paralysis

  • Occurs in the context of Dorsal Midbrain Syndrome (Parinaud Syndrome)
  • Normal adduction and accommodation
  • Exotropia and diplopia during attempts at near fixation
  • Treatment: base-in prisms

Decompensated Exophoria

  • Diagnosed using alternating cover test
  • Causes
    • fatigue, sedatives, alcohol
    • serious illnesses
  • Asthenopic symptoms with prolonged near work
  • Treatment indicated for significant asthenopic symptoms or progression to intermittent exotropia

Intermittent Exotropia

  • Most common form of exotropia
  • Usually starts before age 4
  • Often involves squinting in bright light
  • Suppression only in exo-position, amblyopia is rare
  • Often presents around age 2 with exophoria that becomes exotropia during visual inattention, bright light, fatigue, or illness
  • Classification:
    • Exotropia for distance
    • Exotropia for near
    • Nonspecific exotropia with the same angle of strabismus for distance and near
  • Therapy: glasses, consider reducing myopia correction to induce accommodative convergence, convergence training, amblyopia treatment with occlusion therapy, surgery

(Secondary) Sensory Exotropia

  • Due to monocular or binocular vision deterioration from acquired lesions like cataract

Consecutive Exotropia

  • Develops spontaneously in an amblyopic eye or more often after surgical correction of an esodeviation

Differential Diagnoses

  • Duane Retraction Syndrome Type II

Sources

  • EyeWiki Exotropia
  • Kanski‚Äôs Clinical Ophthalmology: A Systematic Approach; John E Salmon MD; Elsevier; 9th Edition (2019)
  • The Wills Eye Manual: Office and Emergency Room Diagnosis and Treatment of Eye Disease; Kalla Gervasio MD, Travis Peck MD et al; Lippincott Williams&Wilkins; 8th Edition (2021)