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Ocular System

Amblyopia

Partial reversibele loss of sight in one or both eyes, in the absence of ophthalmoscopic or other marked objective signs.

Partial reversibele loss of sight in one or both eyes, in the absence of ophthalmoscopic or other marked objective signs.

  • Functional Amblyopia
    • Physical suppression of retinal image
    • Casue: anisometropic, strabismic or stimulus deprivation (amblyopia ex anopsia)

Etiology

Amblyogenic factors:

During visual development (birth to 6-7 years)
  • Visual (form sense): Anisometropia
  • Light deprivation: Congenital cataract
  • Abnormal binocular interaction: Strabismus

Classification

  1. Strabismic amblyopia (M/C)
  2. Stimulus deprivation amblyopia (amblyopia ex anosmia)
    • Congenital/traumatic cataract, complete ptosis, dense central corneal opacity
  3. Anisometropic amblyopia
    • High degree of refractive error in fellow eye
    • Anisohypermetropic > anisomyopic
  4. Isoametropic amblyopia
    • Bilateral uncorrected high refractive error
  5. Meridional amblyopia
    • Uncorrected astigmatic refractive error
    • Selective amblyopia for specific visual meridian

Presentation

  1. Visual acuity reduced
  2. Effect of normal density filter
  3. Crowding phenomenon
  4. Fixation pattern
  5. Colour vision

Management

  • Occlusion therapy (mainstay): Occlusion of normal eye to force use of amblyopic eye
  • Penalization: Blurring of vision of normal eye
    • Types:
      1. Atropine penalization
      2. Optical penalization
  • Pleoptic exercises: To reestablish foveal fixation
  • Pharmacological manipulation
  • Perceptual learning
  • Computerized home vision therapy (CHVT)

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