Exotropia

• Exotropia


  • Primary -> constant + intermittent
  • Intermittent -> near, distance, non-specific
  • Distance -> true + simulated
  • Simulated -> ac/a and fusion
• Secondary XOT


  • Aka sensory
  • Usually follows visual impairment
  • Unilateral bc of pathology
  • Older px
  • Younger more likely to have SOT bc they have accom
  • No fusion causes eye to drift
  • Constant bc no fusion
• Consecutive XOT


  • Was SOT/SOP
  • Often constant
  • Iatrogenic post op over correction
  • After sx for eso deviation
  • Slow divergence through time
• Primary constant XOT


  • Always there under all viewing conditions
  • Ensure nil pathology/neurological issues
  • Refer to HES esp if under 2
• Intermittent near XOT


  • Adults>
  • Problems with near work
  • Headaches/dip/asthenopia
  • XOT at near and Ortho at distance bc of BSV
• Intermittent non-specific XOT


  • Intermittent XOT/BSV at any distance
  • Can be right or left-switches
  • Dip unlikely bc suppressio
  • Any age
• Intermittent distance XOT


  • Manifest in distance
  • Most common in hospital
  • Can be intermittent/constant
  • Dip rare bc suppression
  • Near- BSV/good stereopsis
  • Distance: XOT
  • May close one eye in bright light
• True distance XOT


  • Near: BSV
  • Distance: XOT
• Simulated distance XOT


  • Controlled XOT at near by accom(high AC/A ratio) so put +3.00 lenses in front of each eye
  • Fusion which you can eliminate by patching
  • It basic looks like an XOT but isnt
• VA as an investigation of XOT


  • Amblyopia is common in constant but uncommon in intermittent unless decompensated and untreated in early childhood
  • Secondary XOT from ocular pathology + amblyopia = reduced VA
• Cover test as an investigation of XOT


  • Diagnose XOT
  • XOP-size/recovery
  • Manifest/latent
  • Near/distance
  • Accom target/light
  • DistanceXOT- controlled at near but how well?- look at recovery
  • DistanceXOT- +3.00DS lens in front of either eye which stops accom so it becomes manifest at near
  • Distance XOT- occlusion. Occlude one eye for 20 mins. Breaks fusion. Eye under patch will deviate outwards. Remove occluder- regains fusion. Measure with PCT. If measurement inc to same as distance =simulated distance XOT controlled by fusion
• Ocular motility as an investigation of XOT


  • Might find scars on sclera where LR was
  • Versions/ductions limitations common in prev strab surgery
• Binocular functions as an investigations of XOT in general


  • Stereopsis/fusional reserves/simultaneous perception/cover test
  • Indicated by the history
• Binocular functions in intermittent XOT


  • Test at distance where deviation is controlled
  • Distance: synoptophore/FD2 distance stereo test/fusion range
  • Near: fusion rang/lang/randot/TNO/20 BO test for both eyes
• Differentiating between true distance and simulated distance XOT


  1. Repeat PCT with +3.00DS lens

  2. If inc in near angle, simulated by accom

  3. Repeat PCT with occlusion

  4. If inc in angle, simulated by fusion
• Principles of management


  • Achieve best possible VA in each eyes
  • Exclude pathology
  • Correct diagnosis/management
  • Achieve BSV - usually has symptoms, all distances
  • Reconstructive care- no symptoms and no BSV
• Orthoptic exercises


  • Improve NPC
  • Positive relative convergence
  • Useful sometimes in XOP/T and decompensating
• Other management options


  • Observe
  • Not sure so can refer
  • Exclude pathology
  • Chn under 5
  • Treatment not working
  • Wants surgery/botox
• Who should you treat


  • Not worried about
  • No neurological/systemic associations
  • 5+
  • Adults
  • Referred back to community
  • Prisms/manipulate rx/exercises