Amblyopia

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)

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Etiology

Amblyogenic factors:

During visual development (birth to 6-7 years)

• Visual (form sense): Anisometropia
• Light deprivation: Congenital cataract
• Abnormal binocular interaction: Strabismus

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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

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Presentation

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

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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)