Management Of Amblyopia

• Amblyopia: reduced BCVA by at least one line due to visual deprivation or abnormal binocularity, with no other cause evident
• Occurs in the first 7-8 years
• Reduced cell numbers seen in LGN and visual cortex

Key features

• Reduced visual acuity and contrast sensitivity
• Crowding: acuity scores are higher with single optotypes
• Normal ocular exam
• Eccentric fixation
• Monocular suppression

Types

• Strabismic: although rare in intermittent exotropias and infantile esotropia with alternative fixation
• Refractive: especially high hyperopia, anisometropia or high astigmatism (>1.5D)
• Visual deprivation: including ptosis, congenital cataracts, corneal disease etc.

Stepwise management

• Depends on

  • Age
  • Cause
  • Severity

• Remove/ameliorate causes of visual deprivation eg. cataracts, ptosis

• Refractive correction with spectacle adaptation for 18 weeks

  • Correct anisometropia of >1.00D

  • Correct astigmatism of >1.50D

  • Correct myopia fully if:

    • >3.5 years old
    • VA below 6/9
    • Myopia greater than -0.75D

• Occlusion therapy (Pediatric Eye Disease Investigator Group 2003 and 2005)

  • Duration rule of thumb: maximum of one week per year of age
  • Continue until VA stable for 3-6 months then taper
  • Always start occlusion therapy before any planned strabismus surgery

• Ages 3-7

  • 6/12-6/24 (moderate) : 2 hours per day
  • 6/30-6/120 (severe): 6 hours per day

• Ages 13-17

  • Trial of 2-6 hours per day may improve vision

  • 25% recurrence risk overall

• Penalisation therapy
  • If occlusion fails or non-compliance
  • Ages 3-7 and 6/12-6/24 (moderate): atropine equal to 6 hours per day occlusion (Pediatric Eye Disease Investigator Group 2002)
  • Can also be achieved optically by undercorrecting the better eye