Amblyopia treatment studies & treatment.pptx

Relevant amblyopia treatment studies

1. AMBLYOPIA STUDIES & TREATMENT IN CHILDREN DR. FASHOLA M.B.

2. Outline Introduction Epidemiology Risk factors Pathophysiology Aetiology Classification Clinical features Management Amblyopia Treatment Studies (ATS) Follow up Prevention References

3. Introduction Amblyopia is an acquired decrease in best corrected visual acuity (BCVA) for which there is no identifiable pathology of the eye or visual pathway. Unilateral or bilateral (rarely). Clinically, amblyopia (monocular) can be defined as a difference in BCVA of 2/more lines (or >1log unit)between the two eyes, in the absence of an organic lesion.

4. Introduction… It signifies a failure of normal neural development due to an abnormal visual experience early in life when the visual system is immature and plastic (critical period). Critical period: extends roughly from birth through the end of the first decade. Susceptibility is greatest during the first few months of life and decreases gradually thereafter.

5. Introduction… Failure to diagnose and manage amblyopia before the age of 8 years can result in life-long visual impairment. It can result from form vision deprivation and/or abnormal binocular interaction in the sensitive period of development.

6. Epidemiology Variable, WHO estimates global prevalence of 1.0 - 5.0%. 19million children <15 years of age are visually impaired, 12 million of these are impaired due to uncorrected refractive errors and amblyopia. Preschool/School age children: 4.0 – 5.3% No sex predilection.

7. Epidemiology… Multi-ethnic pediatric eye disease study (MEPEDS) varies with ethnicity African-American children (1.5%); Hispanic or Latino children (2.6%) Refractive amblyopia (75%) > Strabismic > Form deprivation. Anisometropia was the commonest cause of refractive amblyopia. Prevalence in Nigeria (school-based studies) - Ikuomenisan et al : 0.1 – 3.1%. No significant age or sex predilection. Refractive amblyopia most common.

8. Risk factors Any media opacity greater than 1 mm in size. Manifest strabismus >8 prism diopters (PD) in straight-ahead gaze. Refractive errors (Children ages 12-30months) Astigmatism >2.0 D Hyperopia >4.5 D Anisometropia >2.5 D Myopia ≥-3.5 D Children ages 31-48 months Astigmatism >2.0 D Hyperopia > 4.0 D Anisometropia >2.0 D Myopia ≥-3.0 D Children >49 months of age Astigmatism >1.5 D Anisometropia >1.5 D Hyperopia >3.5 D Myopia ≥-1.5 D

9. Pathophysiology Amblyopia occurs when there is a disruption in the visual pathway development process. 2 mechanisms Lack of exposure to the sharply focused images necessary for normal development disturbs and limits the maturation of form vision. Marked disparity in the quality or direction of input from the two eyes precludes binocular fusion and results in abnormal competitive binocular interaction, which leads to active interference with, or exclusion of, one eye's input to higher visual centers which persists during monocular viewing.

10. Pathophysiology…

11. Aetiology Visual Deprivation Monocular: Strabismus, Anisometropia. Binocular: Bil . Uncorrected High refractive errors. Visual Axis Obstruction Monocular: Unilateral mature cataract, Unilateral corneal opacity, Ptosis. Binocular: Bilateral mature cataract. Abnormal Binocular Interaction Strabismus, Anisometropia . Mixed aetiology

12. Classification/Types Strabismic Amblyopia Stimulus deprivation Amblyopia/Amblyopia of disuse Refractive Amblyopia Anisometropic Amblyopia Bilateral Ametropic / Isometropic Amblyopia Meridional Amblyopia Mixed Aetiology

13. Strabismic Amblyopia A common form of amblyopia, occurring in 40% of children with manifest squint (>8PD in straight gaze). Due to abnormal binocular interaction with continued monocular suppression of the deviating eye. Esotropia > Exotropia. Rarely in hypertropia.

14. Stimulus (Form) Deprivation Amblyopia Lack of adequate visual stimulus due to occlusion of the visual axis or severe image blur caused by opacities in the visual axis : Congenital/Early developmental cataract Moderate – Severe Ptosis Corneal opacity Unilateral/Bilateral

15. Refractive Amblyopia Due to defocused retinal image. Bilateral ametropia occurring on account of significant uncorrected refractive error, especially hypermetropia. Hypermetropia of >+5D; Myopia of > -8D; Astigmatism of >2D (Meridional Amblyopia): image blur in one meridian, can be unilateral or bilateral.

16. Anisometropic Amblyopia Caused by asymmetric refractive error between the two eyes, causing image suppression in the eye with the larger error. Difference of >/= +1.00D in hypermetropia >/= -3D in myopia >/= 1.50D of astigmatism.

17. Clinical features – Visual acuity assessment Neonates – 3 months Following light, face Optokinetic nystagmus Visually evoked potential 3-6 months Visually directed reaching Catford drum Preferential looking: Teller/Cardiff acuity cards Lea gratings

18. Clinical features – V/A assessment 6-18 months Worth’s static balls Worth’s rolling balls “hundreds and thousands” pick up test 18months- 3 years Kays pictures Lea symbols Screening Tests for Young Children And Retards (STYCAR) 5 letter test: HOXTV

19. Clinical features – V/A 3-5 years Sheridan-Gardiner test: HOXTVUA E-chart (tumbling chart) Sjogren hand test Landolt’s broken ring ≥ 5 years literate children LogMar chart Snellen chart Near charts: Reduced Snellen , Maclures reading books.

20. Clinical features For unilateral amblyopia Objection to occlusion of one eye Unequal fixation preference behavior Preferential looking difference of two or more octaves (4 card difference on Teller Acuity cards) Best corrected visual acuity difference between the two eyes of ≥2 lines.

21. Clinical features For bilateral amblyopia BCVA < 6/9 in either eye in a child aged 5 years and older. BCVA < 6/12 in either eye in a child aged 4 years to less than 5 years. BCVA < 6/15 in either eye in a child aged 3 years and younger.

22. Features Colour vision tests: abN in amblyopic eyes. Tests for binocularity/Stereoacuity: Titmus fly test, Two pencil test, Worth 4-dot test, Maddox rod test. Contrast sensitivity testing – Pelli Robson chart Ocular alignment and motility. Lid – Ptosis. Conjunctiva.

23. Features Cornea: Opacity A/C: Deep/Shallow Pupil: Some studies reported anisocoria with pupil in the amblyopic eye being 0.5mm larger. APD has also been reported in some studies. Lens: Cataract

24. Features Fundus: Assess red reflex in both eyes; Look for pathologies that may account for visual loss. Electroretinogram : significantly decreased amplitudes in moderate to severe amblyopia. Mild cases however showed no reduction in amplitudes. Visually evoked potential: Reduction in amplitude &slightly prolonged latency.

25. Features Neutral density filter test: A NDF reduces overall luminance without inducing a colour change. Decreased luminance reduces central acuity in normal eyes but has less effect on amblyopic eyes because they’re not using central acuity. Better visual acuity when used with an amblyopic eye than with a normal eye. Cycloplegic retinoscopy/Refraction.

26. Management Early detection via Screening programs. Counselling of patients and parents. Goal of Treatment Normalize V/A in affected eye while maintaining normal vision in other eye.

27. Management… Principles Counselling; Eliminate visual axis obstruction; Correct any significant refractive error; Force use of the amblyopic eye by limiting use of the other eye.

28. Management… Force use of Amblyopic Eye Occlusion of normal eye, by patching: Part-time: Occlusion for 2 – 6hours per day. Full time: Occlusion during all waking hours. Choice is dependent on age of patient and density of amblyopia.

29. Management… 2. Penalization with Atropine Used when compliance with patching is poor. Vision in the normal eye is blurred with use of atropine. Best in relatively mild amblyopia. 3. Optical Penalization – altering the optical correction of normal eye to produce image blur. 4. Others: Temporary tarsorrhaphy, Botulinum toxin to levator muscle. For refractory cases in cases of non-compliance.

30. Management… Mild to moderate Strabismic &/or Anisometropic Optical correction of any significant refractive error Patching for 2-4 hours/day or Atropine Further management of strabismus More aggressive patching for residual amblyopia

31. Management… Severe Strabismic &/or Anisometropic Amblyopia Optical correction of any significant refractive error Plus: Patching (6 hours) or Atropine (weekend-only or two consecutive days) Further management of strabismus Bilateral ametropic amblyopia Optical correction

32. Management… Stimulus deprivation amblyopia Early surgery Early post-op patching Stimulus deprivation amblyopia with concurrent non-form deprivation amblyopia Early surgery Optical correction ± Patching or Penalization

33. Management…Active Pleoptics : Used for active stimulation of the fovea. The peripheral retina is exposed to intense light, after the light source is turned off, the fovea functions better. The fovea can then be directly stimulated directly by a pleoptophore ( Bangerlers method) or indirectly by producing after images (Cupper’s method).

34. Management..Active Treatment using grating stimuli (using CAM vision stimulator): Amblyopic eye is stimulated for 7mins by slowly rotating high contrast square wave grating of differential spatial frequencies. The rotating gratings are thought to provide cortical stimulation. Done once a week for 3 – 4weeks.

35. Management…Active Perceptual learning: involves repeatedly practicing a visual discrimination task e.g. contrast sensitivity, stereo-acuity etc. Done 2hrs/day, 5days/week, for 9months. Video Game playing : Pushes brain function to its limit, enabling the amblyopic visual system to learn, recalibrate and adjust.

36. Management…Active Monocular fixation in a binocular field (MFBF) : Presentation of peripheral stimulation to both eyes and stimulating only the fovea of the amblyopic eye. Interactive binocular Treatment of Amblyopia (I- BiT TM ) : Present separate images to both eyes, preferentially stimulating the amblyopic eye. Makes use of shutter glasses, HD screens.

37. Management…Active Software-base active treatments of Amblyopia (home or office use): AmbP iNet program: Treatment involves visual search of certain things. Designed to improve hand-eye coordination, VA, crowding effect and visual memory. Pharmacological therapy: Levodopa @ 0.55 mg/kg, 3times daily with part-time occlusion treatment in older amblyopic children, initially thought to improve vision in amblyopic eyes . Near activities.

38. Amblyopia Studies Several studies on Amblyopia (Amblyopia treatment studies) by Paediatric Eye Disease Investigator Group (PEDIG). Either Randomized Clinical Trials (RCT) or Prospectice Observational Studies. Mild to moderate amblyopia – VA in ambyopic eye of 6/24 or better. Severe amblyopia - VA in ambyopic eye of 6/30 to 6/120.

39. Amblyopia studies ATS 1 : No significant difference in visual outcome between patching (79%) and atropine group (74%) after 6 months for children aged 3-7 years with moderate amblyopia. ATS 2A : No significant difference in visual outcome between full time occlusion (4.7 lines) and 6 hours occlusion (4.8 lines) after 4 months for children below 7 years with severe amblyopia.

40. Amblyopia Studies ATS 2B : No significant difference in visual outcome between 2 hours occlusion and 6 hours occlusion (2.4 lines in each) after 4 months for children below 7 years with moderate amblyopia. ATS 3 : To determine effectiveness of amblyopia treatment in children aged 7-17 years after 6 months Amblyopia improves with optical correction alone in a quarter of the participants 2-6 hours/day patching + near visual activities + atropine can improve vision if ambylopia has been treated previously among 7-12 year olds

41. Amblyopia Studies ATS 3 (cont’d): 2-6 hours/day patching + near visual activities can improve vision if amblyopia has not been treated previously among 13-17 years. ATS 4 : No significant difference in visual outcome between daily atropine (47%) and weekend atropine (53%) after 4 months for children below7 years with moderate amblyopia associated with strabismus, anisometropia or both.

42. Amblyopia Studies ATS 5A : Refractive correction alone improves VA in 77% and resolved in 27% of 3-7 years with untreated moderate to severe (6/12 – 6/75) anisometropic amblyopia. ATS 5B : After spectacle correction, 2 hours/day + 1 hour of near visual activities moderately improve untreated moderate to severe (6/12 – 6/120) anisometropic amblyopia.

43. Amblyopia Studies ATS 6 : No significant difference in visual outcome between 2hours/day patching + nears visual activities (2.5 lines) and 2hours/day patching + distance visual activities (2.6 lines) after 6months for children aged 3-7 years with moderate to severe (6/12-6/120) anisometropic or strabismic or combined amblyopia. However, children with severe amblyopia may respond to 2 hours/day patching.

44. Amblyopia Studies ATS 7 : Treatment of previously untreated bilateral refractive amblyopia (6/12-6/120) with spectacle correction alone improves binocular VA to 6/7.5 in 74% of children 3-< 10 years by one year. ATS 8 : Weekend atropine + plano lens in better eye did not significantly improve VA in amblyopic eye in comparison with weekend atropine alone among children 3-7 years with moderate amblyopia (6/12-6/30).

45. Amblyopia Studies ATS 9 : No significant difference in visual outcome between 2 hours/day patching and weekend atropine at 17 weeks for children aged 7-12 years with moderate amblyopia (6/12-6/30). ATS 10 : No significant difference in visual outcome between 2 hours/day patching and application of bangerter filter on the spectacle of the fellow eye at 24 weeks as initial treatment for children aged 3- <10 years with moderate amblyopia (6/12-6/24).

46. Amblyopia studies ATS 11 : Combined 6 hours/day patching + daily atropine did not produce a better visual outcome after 10 weeks among children 3- <10 years with residual amblyopia. The study was stopped on the recommendation of data and safety monitoring committee. ATS 12 : Comparison of 2 hours/day patching + active vision therapy with 2 hours/day patching + placebo vision therapy among children aged 7- <13 years with amblyopia (6/12-6/60). Study was terminated due to difficulty with recruitment.

47. Amblyopia studies ATS 13 : Optical correction alone should be considered as initial treatment for strabismic or combined strabismic-anisometropic amblyopia before initiating other therapies. ATS 14 : Evaluation of levodopa as treatment for residual amblyopia among children 8-17 years. Sample size was small but result was promising.

48. Amblyopia studies ATS 15 : Increasing patching hours from 2 to 6 among children 3- <8 years with amblyopia (6/15 – 6/120) ATS 16 : Augmenting atropine for treatment of amblyopia with plano lens in the sound eye ATS 17 : Randomized trial of levodopa as treatment for residual amblyopia.

49. Amblyopia studies ATS 18 : Visual acuity improvement with binocular iPAD game not as good as 2 hours of daily patching in children 5-12 years. Also, 2 hours per day patching is better than binocular iPAD in children 13-17 years. ATS 19 : Comparison of the efficacy and safety of corneal excimer laser surgery versus non-surgical treatment of anisometropic amblyopia in children who have failed conventional therapy due to non-compliance or non-response (ongoing) .

50. Amblyopia studies ATS 20 : 1 hour per day of binocular game play 5 days per week plus spectacle correction vs spectacle correction alone in children 4-12 years of age (ongoing) .

51. Complications of therapy Failure of therapy, with permanent visual impairment. Reverse Amblyopia. Atropine toxicity. Patching-induced strabismus.

52. Follow-up Severe amblyopia, younger patient age, and more aggressive patching generally require closer follow-up than mild amblyopia, older patient age, and less aggressive patching. 3-year-old child on part-time patching can be seen 2 to 3 months after initiating treatment

53. Follow-up In stimulus deprivation amblyopia post-cataract surgery, 1 day, 1 week, and 1 month post-op visit. Thereafter, monthly or bimonthly visits allow for aggressive treatment of amblyopia and monitoring for changes in refraction. Once visual acuity in the amblyopic eye has stabilized over 2 to 3 visits, treatment can be tapered.

54. Follow-up… Maintenance patching of 1–2 hours per day is often prescribed to prevent recurrence of amblyopia after successful patching. Primary therapy should generally be terminated if there is a lack of demonstrable progress over 3–6 months despite good treatment adherence.

55. Follow-up Many amblyopic children will be left with a residual visual deficit despite compliance with treatment, especially those starting treatment at an older age; those with severe amblyopia; and those with form-deprivation amblyopia; Early treatment is essential.

56. Prevention Childhood eye screening for risk factors of amblyopia. Early intervention in eye defects obstructing visual axis. Early correction of significant refractive error.

57. References Megbelayin EO 1 . Prevalence of amblyopia among secondary school students in Calabar, south-south Nigeria. Pediatric Ophthalmology and Strabismus. American Academy of Ophthalmology. Basic and Clinical Science Course. 2016-2017. JJ Kanski. Clinical Ophthalmology. A Systematic Approach. Eighth Edition Elsevier Butterworth Heinemann. London 2007 AK Khurana. Comprehensive Ophthalmology. Fourth Edition. New Age Publisher. New Delhi 2007. Management of Amblyopia, Eyewiki .