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Introduction, Assessment and Management of Amblyopia

Amblyopia Lazy Eye

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Introduction, Assessment and Management of Amblyopia

  1. 1. AMBLYOPIA PREPARED BY: Anis Suzanna binti Mohamad Optometrist
  2. 2. INTRODUCTION What is amblyopia? What are the types of amblyopia? What causes of amblyopia? Classification of amblyopia? What are the sign and symptoms of amblyopia?
  3. 3. What is amblyopia? • “Lazy eye” • A unilateral/bilateral condition • The best corrected VA is poorer than 6/9 in absence of the ocular media and fundus anomalies or ocular disease. • Prevalence:- occurs about 1 in 25 children develop some degree of amblyopia. • High risk of becoming blind.
  4. 4. Normal vision Amblyopia ( Loss of vision)
  5. 5. Reduction clarity of vision in amblyopic eye
  6. 6. How does it happen?
  7. 7. How does it happen?
  8. 8. What causes of amblyopia? • There are four major causes of amblyopia which are: Unequal/Poor visual acuity Unequal refractive error (Anisometropia) Bilateral equal high refractive errors (isoametropia) Uncorrected moderate/high astigmatism Strabismus/Misaligned Eyes  Blockage or deprivation  Toxic
  9. 9. Unequal/Poor visual acuity due to: 1) Unequal refractive error (Anisometropia)
  10. 10. Unequal/Poor visual acuity due to: Uncorrected high myopia Uncorrected high hyperopia 2) Bilateral equal high refractive errors (isoametropia) More than -6.00D to -9.00D More than +4.00D Blurred image form onto the retina because ray of light focused in front of the retina. Blurred image form onto the retina because ray of light focused at the back of retina.
  11. 11. Unequal/Poor visual acuity due to: 3) Uncorrected moderate/high astigmatism Meridional amblyopia is a mild condition in which lines are seen less clearly at some orientations than others after full refractive correction.
  12. 12. Unequal/Poor visual acuity due to: 3) Uncorrected moderate/high astigmatism A Compound myopic B Simple myopic C Mixed astigmatism D Simple hyperopic E Compound hyperopic Clinical types of astigmatism which can lead to meridonal astigmatism if it is not corrected within plastic age.
  13. 13. Constant strabismus or an imbalance in the positioning of the two eyes
  14. 14. Strabismic amblyopia
  15. 15. Blockage or deprivation an opacity in the line of vision-e.g: cataract Due to: -Congenital/traumatic cataract -Congenital ptosis -Congenital/traumatic corneal opacities.
  16. 16. Toxic • Drugs - chloramphenicol, digoxin, ethambuto l • Tobacco- piped smoker, excessive smoker • Alcohol- alcoholic • Chemicals- Lead, methanol • Nutritional disorders - such as Strachan's syndrome, lack of vitamin A and zinc. The optic nerve head in acquired optic neuropathies
  17. 17. What are the types of amblyopia? • The nature of amblyopia differs depending on the cause:- Refractive amblyopia Anisometropic amblyopia Meridonial amblyopia Strabismic amblyopia Visual deprivation amblyopia Toxic amblyopia
  18. 18. Classification of amblyopia Functional Amblyopia • Not due to the diseases in the eye • unilateral/bilateral of the eye • Reversible • Examples: – Refractive amblyopia – Anisometropic amblyopia – Meridonial amblyopia – Strabismic amblyopia Structural/Pathological Amblyopia • Due to lesion in the eye or visual pathway • unilateral/bilateral of the eye • Irreversible • Examples: – Visual deprivation amblyopia – Toxic amblyopia
  19. 19. Type Causes Refractive amblyopia • Uncorrected isometropia • Result :- A blurred image in both eyes. Anisometropic amblyopia (Second in frequency) • Uncorrected anisometropia • Result :- A blurred image in more ametropic eye. Meridonial amblyopia • uncorrected high astigmatism • Result :- A blurred and distorted image in unilateral or bilateral eyes. Strabismic amblyopia (most common) • Constant strabismus • Suppression in deviated eye Functional Amblyopia
  20. 20. Structural/Pathological Amblyopia Types Causes Visual deprivation amblyopia • Opacities in ocular media or structures • Examples:- cataracts, cornea opacities and cloudy vitreous in infants. Toxic amblyopia • Drugs, tobacco, alcohol, chemicals, nutritional disorders.
  21. 21. What are the sign and symptoms of amblyopia? Symptoms • No symptoms • Blurred vision • Reduced vision • Reduced contrast sensitivity Signs • No obvious sign, unless severe abnormality is present. • Rubbing or squinting of eyes • Misaligning eyes • Reduced VA • Droopy eyelid
  22. 22. ASSESMENT
  23. 23. Assessment of deviation – Compare magnitude at distance versus near • Laterality • Concomitancy • frequency – The test is • Cover test • Hirchberg test – Uses pen torch – Corneal reflexes • Bruchner test – Uses ophthalmoscope – Observe the color and brightness of fundus reflexes and compared
  24. 24. Hirschberg test Bruckner test
  25. 25. Strategies in assessment of amblyopia 1. Visual Acuity (VA) • Degree of amblyopia • Crowding phenomena – Normal Snellen Chart • Line Acuity – Single Letter Chart • Single Letter Acuity 2. Neutral Density (ND) Filter • Depth of amblyopia • Differentiate between organic amblyopia or functional amblyopia
  26. 26. 1. Visual Acuity (VA) – Amblyopes perform better when isolated letters are used instead of full chart. – Crowding effect • Single letter acuity – Infant • Teller acuity chart – Preschool-aged children • Lea symbols, HOTV or broken wheel cards – School-aged children • Snellen chart or Log MAR chart
  27. 27. Visual Acuity Chart Snellen Chart Single letter chart
  28. 28. Single Letter Acuity Advantage • Directly measures acuity especially in children 3-6 years old. Disadvantage • Isolated letters can be used, which may lead to under estimated amblyopia visual loss. Solutions:  Crowding bar may help alleviate this problem
  29. 29. Crowding effect • Crowding bar, or contour interaction bars, allow the examiner to test the crowding phenomenon with isolated optotype. • Bar surrounding the optotype mimic the full of optotype to the amblyopia child. E O
  30. 30. Teller acuity chart Lea symbol HOTV
  31. 31. • In strabismic eye, mostly it use other part of area instead of fovea area which consist rod. • Image that form will reduce in contrast. • Hence, it also reduce the visual acuity of the eye.
  32. 32. 2. Neutral Density (ND) Filter • Strabismic amblyopia – Better VA with ND filter compared to the normal eye – The use of a neutral- density (ND) filter in front of the fixing eye enhanced motion-in- depth performance. – exhibit residual performance for motion in depth, and it is disparity based • Anisometropic amblyopia – Cannot be diagnosed with neutral density filter ND bar
  33. 33. Neutral Density (ND) Filter Strabismic amblyopia Anisometropic amblyopia VA increased with ND filter VA cannot be diagnosed with ND filter
  34. 34. Contrast sensitivity test – Detect functional differences between strabismic and anisometropic amblyopes – Strabismic amblyopes showed abnormalities only in the high spatial frequency range – Anisometropic amblyopes showed an abnormal function both in the low and high spatial frequency range
  35. 35. Contrast sensitivity test Pelli-Robson contrast sensitivity chart Functional Acuity Contrast Test (FACT)
  36. 36. The contrast sensitivity function • A- normal contrast sensitivity function • B- mid to low contrast sensitivity losses • C- more severe refractive errors or severe amblyopia • D- Mild refractive error or mild amblyopia Examples of how the CSF is altered due to refractive error or disease. * The pivotal visual developmental study of Harwerth et al.
  37. 37. Eccentric fixation – Fixate away from fovea • In strabismic amblyopic eye – Visuscopy • Detect and assess eccentric fixation • Explain decreased vision and lead to a more accurate measurement of strabismus • Grid center is temporal to foveal reflex(temporal EF) • Grid center is nasal to foveal reflex(nasal EF) • Grid center is superior to foveal reflex(superior EF) • Grid center is inferior to foveal reflex(inferior EF)
  38. 38. Eccentric Fixation
  39. 39. Binocularity/stereoacuity test – Ambyopia reduced VA, it also has reduced stereopsis – Stereo smile for infant – Preschool random-dot stereogram or random-dot test for preschool children TNO test
  40. 40. Stereo smile Random-dot stereogram
  41. 41. Refraction – commonly can determine anisometropia – Cycloplegic refraction • Spasm the ciliary muscle to inactive the accommodation by using drug – Uses 1% cyclopentolate hydrochoride – Usually more hyperopic or more astigmatic eye for the amblyopic eye
  42. 42. External and internal ocular examination of the eye – Determine either it is visual deprivation amblyopia or afferent pupillary defect are characteristic of optic nerve disease but occasionally appear to be present with amblyopia – To rule out ocular pathology – These examination consist of assessment • Physiological function • Anatomical status
  43. 43. MANAGEMENT Goal of treatment Passive therapy •Optical correction •Occlusion •Penalization Active therapy •CAM visual stimulator •Intermittent photic stimulation (IPS) •Pleoptics
  44. 44. GOAL OF TREATMENT: to restore and improves visual acuity by two strategies: 1. present CLEAR retinal image to the amblyopic eye • eliminate causes of visual deprivation • correcting visually important refractive errors 2. make the child use the amblyopic eye • Recommended treatment should be based on – patient’s age, visual acuity, compliance with previous treatment & physical, social and psychological status
  45. 45.  CHOICES OF TREATMENT the choices of treatment of amblyopia are used alone or in combination to achieve goal of treatment 1. Passive therapy: The patient experiences a change in visual stimulation without any conscious effort i. Proper refractive correction ii. Occlusion iii. Penalization
  46. 46. Passive therapy: i. Proper refractive correction • PURPOSE: – to provide sharp images and providing OPTIMAL environment for amblyopia therapy • Give pt proper optical correction alone – Short period of time (6-8 weeks) before initiation of other therapy
  47. 47. Passive therapy: ii. Occlusion • PURPOSE: cover good eye to stimulate amblyopic eye • Enable the amblyopic eye to enhance neural input to the visual cortex • Decreasing inhibition better eye
  48. 48. • occlusion can be classified in several ways: – Ways of patching • adhesive patch • spectacles occlude • opaque contact lens – Type • direct occlusion: to stimulate amblyopic eye • inverse occlusion: to weaken eccentric fixation – Duration • full time occlusion : for deprivational amblyopia • part time occlusion : to help preserve fusion
  49. 49. • Ways of patching – There are several ways of patching – Excluding light and form: • Adhesive patching • Spectacle occlude • Opaque contact lens – Excluding form (ie: frosted glass)
  50. 50. - Partial patching form • allow appreciation of form but diminish acuity – ie. Translucent materials (Bangerter foil) – foil is cut to size and positioned on inner lens surface • or occlusion covering part of spectacles – ie. Lower half of spectacles – to promote use of the amblyopic eye for near work
  51. 51. • Type • Direct occlusion • Patch the good eye • stimulate amblyopic eye • Indication for • deprivation amblyopia • anisometropic amblyopia
  52. 52. • Inverse occlusion • For amblyopia associated with EF --> strabismic amblyopia • Patching the amblyopic eye • To weaken eccentric fixation of amblyopic eye • If children under 5 year old age • direct full time occlusion may risk reverse amblyopia • Do direct occlusion alternate with inverse occlusion • Ie: for 3 years old children, may need 3 days direct and 1 day indirect occlusion consider 1 cycle and repeated period of time
  53. 53. • Duration – Based on binocular vision status, age, performance need • Full time occlusion • 24 hours a day/waking hours • For children over 7 years over plastic age • When there is no binocular vision • strabismic amblyopia – Alternate strabismus – Constant strabismus • Also anisometropic amblyopia with poor binocular vision • Shows more rapid development
  54. 54. • Part time occlusion • For specific periods / prescribed activities • When binocularity is present • anisometropic amblyopia • To help preserve fusion • Prevent occluded eye become amblyopic if doing full time occlusion • Children under 4 years • 2 hours per day • Prevent deprivation amblyopia in good eye
  55. 55. • Occlusion is maintained until there has been no further improvement for the last 5- 6 weeks • Frequent check are necessary to monitor ocular health, binocular status and each eye’s acuity
  56. 56. 1. Drug penalization • 1 gtt of 1% atropine instilled daily • to good eye • Provide sufficient blur to force the child • use amblyopic eye at near • good eye at distance 1. Has cosmetic advantages and does not totally disrupt binocular vision • Effective method of treatment • for mild to moderate amblyopia in children Active therapy: Penalization
  57. 57. 2. Optical penalization • Children who do not tolerate patching • Fog the good eye (non- amblyopic eye) +3.00 D • Amblyopic eye use for distance and good eye use for near • Not practically applicable – Do near work most of time compared to distance
  58. 58. 2. Active therapy: • is designed to improve visual performance by the patient ‘s conscious involvement in a sequence of a specific, controlled visual task that provide feedback i. CAM visual stimulator ii. Intermittent photic stimulation iii. Pleoptic
  59. 59. Active therapy: i. CAM visual stimulator • Treat amblyopia – by intense visual stimulation for short period of time • Grating of different spatial frequency are rotated in front of amblyopic eye • The good eye is occluded • Method based on: – cortical cell response to specific line orientation and to certain spatial frequency. – Therefore rotation ensured that a large range of cortical neurons are stimulated • Better for anisometropic amblyopia
  60. 60. Active therapy: ii. Intermittent photic stimulation • Mallet IPS unit • described as the "heightened response" to a visual stimulus • The targets – consisted of slides containing much detail of varying type and angular dimension – viewed against a red flickering background. • Red slight stimulation at 4Hz • detailed visual task for 20-30 minutes
  61. 61. 1. 2. 3. 4.
  62. 62. Active therapy: iii. Pleoptics • Purposes : – To disrupt eccentric fixation in strabismic amblyopia • Apparatus based on ophthalmoscope principle • Euthyscope, projectoscope, pleutophore • Exposed peripheral retina to a very bright light while protecting the macular area • Only suitable for children >7 years old Euthyscope
  63. 63. Surgery If amblyopia is due to: • cataract  cataract surgery • nonclearing vitreous opacities vitrectomy • corneal opacities  corneal graft • Blepharoptosis  tarsal tuck
  64. 64. THANK YOU