passive therapy in management of amblyopia
TRANSCRIPT
Passive Therapy in Management of Amblyopia
Maharajgunj Medical Campus, IOM, Nepal
Bikash SapkotaB. OptometryFinal Year
IMPORTANCE OF TREATMENT
If left untreated, amblyopia produces a range of functional deficits
Binocular function is also compromised
The presence of amblyopia (or its treatment) impact on educational attainment, future career opportunities, self-esteem & quality of life
The studies reveal the practical and emotional impact of amblyopia and provide additional evidence in support of the need to develop effective treatment
Goal of Treatment
To restore and improve visual acuity by two strategies:
I. Present clear retinal image to the amblyopic eye
o Eliminate causes of visual deprivation
o Correcting visually significant refractive errors
II. Make the child use the amblyopic eye
Recommended treatment should be based on
o Pt.’s age, VA, compliance with previous treatment &
physical, social and psychological status
What would be the perfect amblyopia therapy?
Effective Good compliance Acceptable to pts. and parent Quick Safe Easy to administer Cost effective Well maintained
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
2. Active Therapy
It 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. Pleoptics
ii. Near activities
iii. Active stimulation therapy using CAM vision stimulator
iv. Syntonic phototherapy
v. Role of perceptual learning
vi. Binocular stimulation
vii. Software-based active treatments
viii. Exposure to dark
ix.
Passive
Therapy
Refractive
Correction
OcclusionPenalization
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
- In case of refractive amblyopia, a progressive improvement in
acuity for up to 16 - 22 weeks has been shown in some pts.
after refractive correction (Stewart C. et al 2004)
When to Prescribe
REFRACTIVE ERROR CORRECTION
Improves VA in 25-33% of patients with anisometropicamblyopia and also in strabismic amblyopia
ATS-5 (PEDIG) 2006 concluded that amblyopia improved with optical correction in 77% and resolved in 27%
Chen et al (AJO 2007) concluded that amblyopia improved with optical correction in 93% and resolved in 45%
Penalisation and occlusion is required only if the VA doesn’t improve with glasses for 4 months
Occlusion Therapy
The most powerful and effective means of treating amblyopia
Mainstay of treatment since 18th century to till now
Highly effective until 8 years of age
New studies have shown improvements upto 24 yrs of age
Cover good eye to stimulate amblyopic eye
Success rate 30-92%
o When fixation is central: simple & effective
o When fixation is eccentric: <7yrs central fixation recover
o Older the child harder to regain central fixation
Mode of Action
Prevent fixating eye taking part in act of vision and removes inhibitory stimulus that arises fromstimulation from fixating eye (non-amblyopic eye)
TYPES OF OCCLUSION
Occlusion
Total or
Partial
Conventional
or Inverse
Full Time or
Part Time
Total VS Partial Occlusion
Total Partial
•All light is prevented fromentering eye•Employed in amblyopic eyes
with acuity less than 6/24•Occlusion using elastoplast, gauze pad, tape, doynes rubber occluder
•Does not cut off the total lightentering eye•Degrades the vision of normaleye such that amblyopic
eyegets better vision andpreference•Occlusion using cellophane,transparent nail polish, or
a
Conventional VS Inverse
Conventional Inverse
•Occlusion of sound eye
•Occlusion of amblyopiceye so that eccentricfixation becomes less
fixedFull Time VS Part Time
Full time Part time
Removed only while going to bed at night
Short time each day during close work or watching television
Choice of initial Rx In relapses after Rx and also for maintenance
PatchesMicropore tape with soft tissue paper
Spectacle patch / frost glassDoyne’s occluder Opaque Contact Lens
How to go about Occlusion?
Motivation of child and parents
Active vision exercises by amblyopic while non-amblyopic eye is occluded
Occlusion is continued till amblyopic eye has developed equal vision and equal preference of fixation
May take 3-6 months
If there is no improvement, then treatment is stopped
Maintenance treatment is continued at least up to 9 yrs of age with part time occlusion and exercises
Follow up-depending on age, severity of amblyopia and compliance-to look for VA, fixation pattern and occlusion amblyopia
When to stop occlusion
- VA equals in both eyes
- Alternation of fixation (Repka 2008)
When VA is stable patching may be decreased slowly
Because amblyopia recurs in large no. of pts. maintenance therapy or tapering of therapy should be strongly considered
Disadvantages of occlusion
Prolonged treatment
Occlusion amblyopia
Non compliance
Psychological distress
Allergic skin rash
Cosmetically inacceptable
Prognostic considerations
Younger the age better the prognosis
Type of amblyopia myopic anisometropia> hyperopic anisometropia> strabismicamblyopia> stimulus deprivation
Pre-treatment VA
Type of occlusion
Type of fixation
Near exercises
Pt. compliance and parent education
Presence of astigmatism
Previous treatment
Refractive correction
Treatment of Anisometropic Amblyopia
Treatment of Strabismic Amblyopia
Penalization
Therapeutic technique performed by optically defocusing the eye with better vision by using cycloplegia or altering the eye glass lens
Indications
o No compliance for occlusion
o Mild degrees of amblyopia
o Maintainence after occlusion
o Anisometropic amblyopia
Advantages: Cheap, better compliance
Disadvantages: Side effects of drugs
- Risk of occlusion amblyopia
- Systemic absorption
Unless penalisation decreases the VA of dominant eye below the amblyopic eye this form of treatment is not adviced
Methods of penalisation
a. Near penalization: fixing eye is atropinized & fullycorrected for distance, amblyopic eye isovercorrected with +2.00 to +3.00 D
b. Distance penalization: fixing eye is atropinized & overcorrected, amblyopic eye is fully corrected
c. Total: fixing eye is atropinized & undercorrectedby 4.00 to 5.00 D, amblyopic eye is fully corrected
Summary of the PEDIG studies
Short title
Ages (Yrs)
Baseline amblyopic eye acuity
Primary outcome measure
Initial treatment prescribed
Results (Improvement)
Primary conclusion
ATS 1 (35)
3 to <7
20/40-20/100
Lines improvement after 26 weeks
Daily atropineAt least 6 hrs daily patching
2.8 lines
3.2 lines
Atropine and patching are equally effective as primary treatment for moderate amblyopia
ATS 2A (37)
3 to <7
20/100-20/400
Lines improvement after 17 weeks
6 hrs daily patching Full time patching
4.8 lines
4.7 lines
6 hrs daily patching produces improvement similar to full time patching for severe amblyopia
ATS 2B (36)
3 to <7
20/40-20/80
Lines improvement after 17 weeks
2 hrs daily patching6 hrs daily patching
2.4 lines
2.4 lines
2 or 6 hrs of prescribed daily patching produce similar improvement for moderate amblyopia
Summary of the PEDIG studiesShort title
Ages (Yrs)
Baseline amblyopic eye acuity
Primary outcome measure
Initial treatment prescribed
Results (Improvement)
Primary conclusion
ATS3 (39)
7 to <18
20/40-20/400
Proportion of responders (improvement >2 lines) after 24 weeks
2-6 hrs daily patching (+ atropine if <12 yrs)
Spectacles alone if needed
Response rates:Age≤12 yrs: 53%Age≥13 yrs: 25%Age≤12yrs: 25%Age≥13 yrs: 23%
ATS 4 (34)
3 to <7
20/40-20/80
Lines improvement after 17 weeks
Weekend atropineDaily atropine
2.3 lines
2.3 lines
Weekend and daily atropine produce similar improvement for moderate amblyopia
ATS 5 (38)
3 to <8
20/40-20/400
Lines improvement after 5 weeks
2 hrs daily patchingSpectacles alone if needed
1.1 lines
0.5 lines
After a period of spectacle wear, 2 hrs daily patching is superior to continuing spectacles alone
Practical Implications of the PEDIG studies
Children < 7 yrs and VA between 6/12 to 6/24
- 2 hrs and 6 hrs patching - same effect
Children < 7 yrs and VA 6/30 - 6/120
- 6 hrs and full time patching - same effect
Children < 7 yrs and VA 6/12 - 6/30
- Daily atropine produces similar effect as 6 hrspatching
Practical Implications of the PEDIG studies
Children 7 to 18 yrs and VA 6/12 to 6/120
- 2 - 6 hrs patching leads to at least 2 lines improvement
(if no previous treatment) but
- the compliance rate is poor in age >13 yrs
Children < 8 yrs and VA 6/12 - 6/120
- Patching 2 hrs is better than spectacles alone
Amblyopia is still an unsolved problem, the best modality of treatment is still to be
explored in future
Thankyou