4 - Amblyopia Flashcards
Amblyopia
- aka
- occurs when
- causes
Functional amblyopia, lazy eye
The visual pathway failed to develop properly due to inadequate stimulation (pathway halted during visual immaturity)
Form deprivation and/or abnormal binocular interaction
Amblyopia
- corrective lenses
- pathology
- frequency (% population)
Cannot improve
Absent
2-4%
Amblyopia
- most common cause of __
- laterality
- suspicious VA findings
Monocular visual impairment in children & mid-age adults
Uni or bi
Loss of at least 2 lines
Critical period
- age
- abnormal input after CP
- effect of amblyogenic factors
- can you tx too early, late
Up to 8-10 yo
Blur (-) halt to sensory development
Different factors may affect differently (e.g. aniso vs isometropia)
Yes - too early may affect emmetropization, too late may lead to amblyopia
Risk factors for amblyopia
Prematurity Low birth weight ROP Cerebral palsy Mental retardation Genetic syndromes Family hx Maternal smoking, alcohol, drugs
Amblyogenic conditions: refractive
- cause
- examples
Blur
Anisometropia
Isoametropia
Meridonal
Amblyogenic conditions: form deprivation
- cause
- examples
Degraded image or occlusion
Cataract Ptosis Corneal opacity Post seg hem (e.g. shaken baby) Prolonged penalization/occlusion
Amblyogenic conditions: strabismus
- cause
- examples
Different targets/no bifoveal fixation
ET
XT
Hypertropia
Isoametropic amblyopia
- describe
- hyperopia
Very high refractive error OU
High hyperopia may cause an ET - may not if child is not in school/has no need to accomm -> didn’t develop a strab
Anisometropic amblyopia
- describe
- common complaints
Normal refractive error one eye, other significant refractive error & reduced acuity
“That’s my bad eye”
“My left eye never sees well”
Hyperopic anisometropic amblyopia
- as little as __
- if both eyes are hyperopic, __
- __ can be affected
- W4D
1D
Less hyperopic can maintain control, keep some motor & sensory fusion
Stereo
Can show fusion, may also pick up a central scotoma
Myopic anisometropia
-moderate
Less than 5D
Can be “good” for you - one eye sees D, other N
Amblyopia unlikely to develop bc each eye attains clarity at a certain distance
- 0.75 OD (sees D)
- 3.25 OS (sees N)
Meridonial amblyopia
-describe
Uncorrected high astigmatism in one/both eyes
Amblyogenic refractive errors: Isoametropia -hyperopia -myopia -astigmatism
H: 5.00 or more D
M: 6.00 or more D
A: 2.50 or more D
Amblyogenic refractive errors: Anisometropia -hyperopia -myopia -astigmatism (meridonial)
H: 1.00 or more D
M: 3.00 or more D
A: 1.50 or more D
Form deprivation
-describe
Obstruction of the line of sight that prevents a clear image to form on the retina
Strabismic amblyopia
- more likely to develop
- less likely to develop
Unilateral
Intermittent or alternating (even constant)
Strabismic amblyopia
-the later the onset of strab, __
The better chance of re-establishing fusion that the pt has already developed
Hysterical amblyopia
- cause
- who
- next steps
Psychological - anxiety, stress
Girls 8-14 yo
Add’l testing: VF, neurological, electrophysiology
Organic amblyopia
- cause
- presentation
- management
Toxic or nutritional
Reduced VA, absolute scotoma, progressive vision loss, optic nerve atrophy
May be reversible, may need low vision aids for profound loss
Tips for handling malingerers
Start VAs at 20/10 Use plano lenses in phoroptor OKN drum (VAs at least 20/200 if they follow grating) Electrophysiology Clover pattern VF Thorough hx When in doubt, cyclo
Studies: patching vs atropine
Both well tolerated
More pts in atropine group had reduced VAs at 6 mo, but did not persist
Both have similar improvement & are appropriate for initial tx of moderate amblyopia children 3-7 yo
Studies: patching vs atropine follow-up
After initial 6 mo, there was no significant difference b/w atropine or patching groups up to 2 years
Studies: full-time vs part-time patching
6 hours of daily patching = full-time patching in tx severe amblyopia in children 3-7 yo
Studies: patching 2 hrs vs 6 hrs
2 and 6 hours of daily patching have similar VA improvement in tx moderate amblyopia in 3-7 yo
Studies: amblyopia tx in children 7-17 yo
Optical correction worked ~25% for both 7-12 yo and 13-17 yo
Treatment worked ~50% for younger, ~25% for older kids
***responded better if they had not been tx before (patching or atropine)
I.e. tx may be of limited benefit if amblyopia was previously tx with patching
Studies: atropine daily vs weekends
Both have ~same magnitude of improvement in children <7 yo (just do weekends)
