Introduction, Assessment and Management of Amblyopia
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Introduction, Assessment and Management of Amblyopia
- 1. AMBLYOPIA PREPARED BY: Anis Suzanna binti Mohamad Optometrist
- 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. 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. Normal vision Amblyopia ( Loss of vision)
- 5. Reduction clarity of vision in amblyopic eye
- 6. How does it happen?
- 7. How does it happen?
- 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. Unequal/Poor visual acuity due to: 1) Unequal refractive error (Anisometropia)
- 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. 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. 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. Constant strabismus or an imbalance in the positioning of the two eyes
- 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. 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. 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. 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. 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. 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. 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. ASSESMENT
- 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. Hirschberg test Bruckner test
- 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. 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. Visual Acuity Chart Snellen Chart Single letter chart
- 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. 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. Teller acuity chart Lea symbol HOTV
- 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. 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. Neutral Density (ND) Filter Strabismic amblyopia Anisometropic amblyopia VA increased with ND filter VA cannot be diagnosed with ND filter
- 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. Contrast sensitivity test Pelli-Robson contrast sensitivity chart Functional Acuity Contrast Test (FACT)
- 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. 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)
- 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
- 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. 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. MANAGEMENT Goal of treatment Passive therapy •Optical correction •Occlusion •Penalization Active therapy •CAM visual stimulator •Intermittent photic stimulation (IPS) •Pleoptics
- 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. 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. 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. 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. • 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. • 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. - 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. • Type • Direct occlusion • Patch the good eye • stimulate amblyopic eye • Indication for • deprivation amblyopia • anisometropic amblyopia
- 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. • 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. • 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. • 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. 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. 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. 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. 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. 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. 1. 2. 3. 4.
- 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. Surgery If amblyopia is due to: • cataract cataract surgery • nonclearing vitreous opacities vitrectomy • corneal opacities corneal graft • Blepharoptosis tarsal tuck
- 64. THANK YOU
Notes de l'éditeur
- Introduction What is amblyopia? neurophysiology of amblyopia types causes Classification sign and symptoms Assessment VA testing Contrast sensitivity test ND filter test Stereoacuity test Eccentric fixation Management Passive therapy Active therapy
- The brain and the eye work together to produce vision. Light enters the eye and is changed into nerve signals that travel along the optic nerve to the brain. Amblyopia is the medical term used when the vision in one of the eyes is reduced because the eye and the brain are not working together properly. The eye itself looks normal, but it is not being used normally because the brain is favoring the other eye. This condition is also sometimes called lazy eye.
- Amblyopia: The brain and the eye work together to produce vision. Light enters the eye and is changed into nerve signals that travel along the optic nerve to the brain. Amblyopia is the medical term used when the vision in one of the eyes is reduced because the eye and the brain are not working together properly. The eye itself looks normal, but it is not being used normally because the brain is favoring the other eye. This condition is also sometimes called lazy eye. Amblyopia is the most common cause of decreased vision in children.
- in normal vision, an image is seen by both eyes and blended into one picture by the brain When one eye is weaker, the brain ignores the image sent by the weaker eye amblyopia or loss of vision results.
- Amblyopia can be caused by anything that interferes with vision for a significant amount of time during the critical period from birth to about 6 years of age.
- poor aim- most common poor focus- most difficult to detect poor clarity- most severe
- most difficult to detect each eye have unequal refractive error Both eye cannot be in focus at the same time Blurred image in one eye is ignored by the brain
- Meridional amblyopia is a mild condition in which lines are seen less clearly at some orientations than others after full refractive correction. An individual who had an astigmatism at a young age that was not corrected by glasses will later have astigmatism that cannot be optically corrected after 2 y/o.
- most common Both eyes not aimed in exactly same direction Brain turns off misaligned eye to avoid double vision
- Age onset of a strabismus: Critical period- developing amblyopia(birth-3y/o)(5-7y/o) -deep constant suppression After critical period/ adulthood- not lead to amblyopia - constant diplopia because suppression of the eye is difficult and the both eyes retain good VA
- most severe disuse/ understimulation of the retina Due to eye disorder- e.g cataract,corneal opacties,ptosis, eyelid tumors,etc. visual not develop well - brain
- Drugs: - chloramphenicol- use in certain infection can cause toxic antibiotics digoxin-Antiarrhythmic Agent ethambutol-Antitubercular Agent Tobacco amblyopia – a condition in which the vision is lost because of the use of tobacco. The toxic effects of tobacco constrict the vessels of the body and interfere with circulation. The optic nerve is very sensitive to tobacco and can be easily irritated by excessive smoke. As a result, the optic nerve swells, a condition known as optic neuritis. Alcohol- disorder involves lost vision, including scotomas (blind spots) and decreased visual acuity within the central portion of the visual field Chemicals- Lead, methanol can cause optic nerve damage Nutritional disorders- Strachan's syndrome Figure 2 The optic nerve head in patients with ischemic optic neuropathies
- Refractive, anisometropic- affected same proportionally the centrally and peripherally. Strabismus – affected foveal area. Meridonial – affected the area along the blurred astigmatic meridian. Visual and toxic- may affected part or entire visual field.
- Amblyopia is primarily a defect of central vision. There is a critical period for sensitivity in developing amblyopia. The time necessary for amblyopia to occur during critical period is shorter for stimulus deprivation than for strabismus or anisometropia.
- Visual deprivation amblyopia It is usually caused by congenital or early acquired media opacity. This form of amblyopia is the least common but most damaging and difficult to treat. In bilateral cases acuity can be 20/200 or worse. Toxic amblyopia Endogenous/ Exogenous poisoning. Most severe
- Characteristics of Amblyopia General characteristics of amblyopia are: 1. Abnormal position of pupil2. Blinking or rubbing eyes frequently 3. Narrowing his/ her eyes or slanting when looking at objects4. Looking at objects in a very close distance 5. Leaning forward or aside when looking at object in distance 6. Having problems when reading, such as skipping words 7. Always making mistake when writing or copying 8. Excessive tearing and sensitive to light 9. Red eyes, swollen eyelid and secretion in eyes 10. Motion sickness when travelling long journey
- The contrast sensitivity function provides a more thorough representation of the visual system. For example, the pivotal visual developmental study of Harwerth et al. (17) characterized the changes in the contrast sensitivity function after different periods of monocular deprivation in monkeys. The loss of sensitivity in the mid to high spatial frequencies was profound during abnormal visual development, with increased deprivation leading to further contrast losses. Not only will certain disease/disorders of the eye reduce visual acuity, contrast sensitivity will also be affected (18). For example, patients with multiple sclerosis will have mid to low contrast sensitivity losses (Fig. 25B), whereas patients with cataracts will have an overall reduction in contrast sensitivity (Fig. 25C). Mild refractive error or mild amblyopia will lead to a CSF similar to D in Fig. 25, with more severe refractive errors or severe amblyopia, resulting in a CSF similar to curve C.
- 1. Passive therapy: The patient experiences a change in visual stimulation without any conscious effort Optical correction Occlusion Penalization 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 CAM visual stimulator Intermittent photic stimulation Pleoptic *Passive therapy (spectacles, occlusion, pharmacological agents). The patient experiences a change in visual stimulation without any conscious effort *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
- Useful to give the patient a short period of time (6-8weeks) with proper optical correction alone before the initiation of other amblyopia theapy
- This animation shows the wiring involved with amblyopia, and why we patch eyes to correct vision.
- 1. Total patching excluding all light and form Adhesive patch Spectacle occlude Opaque contact lens 2. Total patching excluding form only allowing the passage of some light. Semi opaque occlusion material such Blenderm tape or frosted glass, is effectively total occlusion.
- under 5 year old age Full time direct occlusion may risk reverse amblyopia Need to establish alternate occlusion (direct and inverse) Ie: for 3 years old children, may need 3 days direct and 1 day indirect occlusion consider 1 cycle and repeated period of time
- described as the "heightened response" to a visual stimulus when an active exposure to light of one second was alternated with a dark period of thirty seconds provide alternate stimulation of the amblyopic eye with equal dark and light intervals, the frequency of four light flashes persecond (4Hz) being chosen after much clinical experimentation. The targets consisted of slides containing much detail of varying type and angular dimension, and were viewed against a red flickering background. provide alternate stimulation of the amblyopic eye with equal dark and light intervals
- The underlying purposes : eccentric fixation must be disrupted first and then the fovea retrained to resume normal fixation Apparatus based on ophthalmoscope principle Euthyscope, projectoscope, pleutophore Used to exposed peripheral retina to a very bright light while protecting the macular area This resulted in after images, which, if negative, had a clear area corresponding to the macula, which the patient was then trained to localized correctly. Pleoptic treatment was only suitable for older children or adults