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AMBLYOPIA

AMBLYOPIA. Dr Cynthia Arunachalam Prof and HOD. Amblyopia. Partial loss of sight in one or both eyes in the absence of ophthalmoscopic or other objective signs of ocular disease. Critical period – birth to 6 years of age. Types of Amblyopia. 1. Strabismic amblyopia

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AMBLYOPIA

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  1. AMBLYOPIA Dr Cynthia Arunachalam Prof and HOD

  2. Amblyopia • Partial loss of sight in one or both eyes in the absence of ophthalmoscopic or other objective signs of ocular disease. • Critical period – birth to 6 years of age

  3. Types of Amblyopia • 1. Strabismic amblyopia • 2. stimulus deprivation amblyopia • 3. Anisometropic amblyopia • 4. Isometropic amblyopia • 5. Meridonial amblyopia • Strabismus (misaligned eyes) • Media opacity • High refractive errors

  4. Amblyopia: Three Main factors • 1. Media opacity • 2. High refractive errors • 3. Strabismus (misaligned eyes) • 1. Light/stimulus deprivation • 2. Visual / form sense • 3. Abnormal binocular interaction

  5. Stimulus deprivation amblyopia • Congenital cataract • Ptosis • Corneal opacity

  6. Stimulus deprivation amblyopia • Best example: monocular congenital cataract • Total deprivation of sensory input to cortex in one eye with normal sensory input in fellow eye leads to rapid dense amblyopia

  7. Stimulus deprivation amblyopia: Cataract Treatment: • urgent cataract surgery (clearing of media opacity) • may patch both eyes prior to surgery to prevent amblyopia • contact lens to restore focus • diligent patching of unoperated eye after surgery

  8. Stimulus deprivation amblyopia: Others • Other obstruction /opacity preventing light from reaching the retina • Ptotic (drooping) upper eyelid • Corneal scar/opacity • forceps injury at birth • hereditary abnormalities • Vitreous opacity, hemorrhage

  9. Stimulus deprivation amblyopia: Treatment • Clear the media • surgically lift ptotic eyelid • corneal transplant • cataract removal

  10. High Refractive Errors Clear input to the visual cortex is required to develop good vision • Myopia (nearsighted) • eye too long • Hyperopia (farsighted) • eye too short • Astigmatism (distortion)

  11. High Refractive Errors • If retinal image in one eye is severely unfocussed, unilateral amblyopia may result – anisometropicamblyopia • If retinal image in each eye is severely unfocused, bilateral amblyopia may result (uncommon) – isometropicamblyopia • high hyperopia • high myopia • high astigmatism • If retinal image is unfocussed in one meridian only, - meridonialamblyopia may result

  12. Anisometropic Amblyopia • Higher refractive errors in one eye as compared to the other eye. • Hypermetropia 1-2 D • Myopia 3 D

  13. Anisometropic Amblyopia • If retinal image in one eye is unfocused, monocular amblyopia may result (very common) • anisometropia (e.g. one eye normal, one eye moderately farsighted) • often seen in combination with accomodative esotropia

  14. Isometropic Amblyopia • Bilateral High refractive errors • Bilateral Amblyopia

  15. Meridonial amblyopia • Uncorrected astigmatism • Selective for the specific visual meridian

  16. Refractive Amblyopia: Treatment • Glasses - clears retinal image • Patch the better eye - forces brain to use image from “weaker” eye

  17. Strabismic Amblyopia • Unilateral constant squint. • Prolonged uniocular constant suppression.

  18. Amblyopia: Prevention/Early Treatment • Awareness of problem • Overall affects 2-5% of population

  19. Amblyopia: Prevention/Early Treatment Birth • First examination by primary care doctor before newborn leaves hospital • Look for clear, equal red reflex • congenital cataract • hereditary corneal dystrophies • Ocular alignment unreliable in first week of life

  20. Amblyopia: Prevention/Early Treatment Birth to 2 Years Examination at each well baby check – 3 points • 1. Red reflex • 2. Ocular alignment should be orthophoric by 3-6 months • corneal light reflex, alternate cover test • if alignment not straight by 3 months - refer to ophthalmologist • 3. Visual acuity - fix and follow smoothly by 6 months • check each eye separately

  21. Amblyopia: Prevention/Early Treatment 2 Year Check • Red reflex - Bruckner Test • direct ophthalmoscope at 0 power setting, otoscope without magnifier • distance of 2 feet from patient • normal - equal red reflex • unequal refraction - one eye darker reflex • no/poor reflex - media opacity • corneal light reflex not symmetric - strabismus

  22. Amblyopia: Prevention/Early Treatment • Ocular alignment corneal light reflex alternate cover test • Visual acuity fix and follow very smoothly and consistently ask the parent what the child sees - “he sits close to TV” can the child recognize the parent across the room

  23. Amblyopia: Prevention/Early Treatment 6+ Year Checks • Ocular alignment – perfect • Visual acuity - Snellen letters preferable • vision should be 6/6 or better • refer for vision < 6/9 or 2 line difference (i.e. 6/6 one eye, 6/12 other) • External, Anterior segment, Ophthalmoscopicexam

  24. Clinical characteristics • 1. visual acuity: recognition acuity > affected than resolution acuity • 2. Neutral density filter: improvement in visual acuity • 3. Crowding phenomenon: VA is better with single charts • 4. Fixation pattern: degree of amblyopia, central or eccentric • 5. Colour Vision: affected in deep amblyopia

  25. Amblyopia: Conclusion • Straighten the eyes • Clear the media • Correct the refractive error • Occlusion therapy

  26. OCCLUSION THERAPY • Forcing the use of the amblyopic eye by occlusion of the other eye by patching. • Occlusion therapy has been the mainstay of treatment since the 18th century.

  27. OCCLUSION THERAPY • Patching may be full-time or part-time. • Children need to be observed at intervals of 1 week per year of age, if undergoing full-time occlusion to avoid occlusion amblyopia in the sound eye. • The Amblyopia Treatment Studies (ATS) have helped to provide new information on the effect of various amounts of patching.[14, 15]

  28. OCCLUSION THERAPY Patching may be by • adhesive patches, • opaque contact lenses, • occluders mounted on spectacles, • adhesive tape on glasses • full-time patching produced a similar effect to that of 6 hours of patching per day • Always consider lack of compliance in a child where visual acuity is not improving.

  29. Amblyopia: Conclusion Diagnose it early!

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