Peds

Amblyopia

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Amblyopia, Lazy Eye

  • Definition
  1. Poor vision not correctable with eyeglasses
  2. No known primary cause (normal Cornea, lens, Retina)
  3. Greek: "Dullness of Vision"
  • Epidemiology
  1. Prevalence: 2-4% of US Children
  2. Occurs in children up to age 6 years
  3. Most common childhood cause of monocular Vision Loss
  • Etiologies
  1. Strabismus (most common cause of Amblyopia)
    1. Misalignment of eyes
  2. Refractive Amblyopia
    1. Anisometropia
      1. Large difference in Refractive Error between eyes
      2. Causes
        1. Bilateral Hyperopia or far sightedness (most common)
          1. Myopia is less likely to result in Vision Loss
        2. Severe unilateral Hyperopia or Myopia
        3. Astigmatism
        4. Induced Astigmatism
          1. Eyelid Ptosis
          2. Periorbital Capillary Hemangioma
          3. Mild Congenital Cataract
    2. Isometric Amblyopia (Ametropic Amblyopia)
      1. Severe, equal Refractive Errors
  3. Deprivation Amblyopia (least common)
    1. Congenital Cataract
    2. Retinoblastoma
    3. Corneal scarring
    4. Vitreous opacity
    5. Severe Ptosis
    6. Optic atrophy
    7. Iatrogenic excessive patching
  • Pathophysiology
  1. Visual blur at level of Retina coinciding with visual development in early childhood
  2. Occurs in developmentally immature eye
    1. During first 6 months of life
    2. Acuity normally improves rapidly 20/400 => 20/80
    3. Eye fully matures by age 9 years
  3. Normal maturity
    1. Requires clear, equal, aligned image for each eye
    2. Conflicting data with
      1. Strabismus (2 competing images)
      2. Anisometropia (1 clear, 1 blurred image)
    3. Brain suppresses information from the "bad" eye
    4. Continued suppression leads to permanent Vision Loss
      1. Adults unable to suppress different images
      2. Adults experience Diplopia
  • Screening
  1. See Pediatric Vision Screening
  2. Exam for associated ocular disease
  3. Test for Strabismus
    1. Corneal Light Reflex
    2. Cover-Uncover exam
    3. Bruckner Test (Red Reflex)
    4. Fixation and following
  4. Differentiate Refractive Error from Amblyopia
    1. Pinhole Test
  5. Photoscreeners
    1. Red Reflex evaluated in digital flash photograph taken of both eyes
    2. Uncorrected Refractive Error can be inferred from the image
    3. Test Sensitivity is as low as 63% and has a high False Positive Rate
    4. Matta (2009) Arch Ophthalmol 127(12):1591-5 [PubMed]
  • Management
  1. Indications to refer to pediatric ophthalmology
    1. Family History
      1. Sibling requiring glasses before age 2.5 years
    2. Infant Findings
      1. RetinoblastomaFamily History
      2. Abnormal Red Reflex
      3. Abnormal eye tracking after age 3 months
      4. Strabismus
      5. Chronic eye tearing or discharge
    3. Childhood findings
      1. Strabismus
      2. Age 3.5 to 5 years
        1. Vision worse than 20/40 in either eye
      3. Age >5 years
        1. Vision worse than 20/32 in either eye
        2. Child not reading at grade level
  2. Treat underlying cause early
    1. Address Congenital Cataracts and Refractive Error if present
    2. Correct Strabismus if present
  3. Previously, encouraged children to write or draw while good eye obscured
    1. However near activities have not been found to improve Amblyopia
  4. Force child to use amblyopic eye by obscuring good eye
    1. Approach
      1. Late presenting, older children with more significant Amblyopia typically receive more aggressive approach
        1. Sustained glasses and patching
      2. Patching for 2 hours daily is as effective as 6 hours daily in moderate Amblyopia (20/40 to 20/80)
    2. Manual methods
      1. Patch "good", dominant eye (usual course)
      2. Opaque Contact Lenses
      3. Cloth over glasses on good eye side
      4. Prescription glasses to blur good eye
      5. Bangter Filter (graded adhesive applied to glasses lens over the good eye)
    3. Atropine (0.5-1%) 1 drop daily for 2-7 days per week
      1. Indicated in noncompliant children
      2. Most effective in far sightedness
      3. Apply to good eye to dilate pupil
      4. Prevents accommodation and causes vision blurring
  • Prognosis
  1. Early, aggressive, and consistent therapy is critical
    1. Most responsive before age 3-5 years old
  2. Amblyopia recurs in 24% after 1 year
    1. Be vigilant about surveillance
  3. Amblyopia nearly irreversible after age 9 years
    1. New studies suggest teens may benefit from therapy
    2. Scheiman (2005) Arch Ophthalmol 123:437-47 [PubMed]
  1. Information from your Family Doctor
    1. http://www.familydoctor.org/handouts/460.html