What is amblyopia?

-unilateral or bilateral decrease of vision for which on obvious cause can be detected by physical examination of the eyes and in appropriate cases is correctable with therapy

-significant reduction in VA which cannot be improved by refractive correction in which has no obvious organic cause

When is the "Period of Visual Immaturity"?

What constitutes amblyopia?

What is always maintained?

What percentage are above the VA of 20/100 at time of diagnosis?

What is the inter-ocular difference in unilateral cases

-

-Sometime around the first 6 years of life

-Corrected VA 20/25- 20/200; may limit to 20/40

-light perception is always maintained

-75%

->/= 2 lines

What is the prevalence of amblyopia?

What percentage of the general and optometric population will have amblyopia?

Amblyopia is the leading cause of ____?

How many children per year are diagnosed with amblyopia?

Can amblyopia occur in adults?

-2-2.5%, 3-5%

-1.6% to 3.6%

-monocular vision loss

-60,000

-yes, but because it was never found in childhood

-poor binocular vision

-poor school performance

-poor self-perception of social acceptance

-increased risk of bilateral blindness caused by trauma in younger pts and AMD in older patients

What patients are at risk for developing amblyopia? (5)

Which strabismus is the most common cause of amblyopia?

-children less than 6 manifesting either strabismus, large bilateral ametropia, anisometropia, ptosis, or cataract (unilateral or bilateral)

-ET, constant, unilateral

What are the three classificaitons of amblyopia?

Which is the most common?

-organic

-psychogenic

-funcitonal

-functional***

What causes organic amblyopia?

When is the onset of organic amblyopia?

-components of the visual pathway fail to develop due to inherited structural defects or the functioning of the normal visual pathway may be impaired due to metabolic or toxic disturbances

-onset can be at any age

-typically bilateral reduced corrected VA

-non-observable histopathology

-visual field defect- central or cecocentral scotoma

-color vision shows dyschromatopsia

-case history is significant

What are the three types of Orangic amblyopia?

What is the cause of nutritional organic amblyopia?

What are some of the causes of these vitamin deficiencies?

Is visual loss gradual or immediate?

What would the VF show?

What about peripheral vision?

What about the fundus?

-loss of central vision due to dietary insufficiencies more specifically lack of B vitamins (B1, B2, B6, B12)

-alcoholism and excessive tobacco use

-gradual and develops over days, weeks, months

-bilateral and roughly symmetrical central, paracentral, and centrocentral scotoma, and larger on red than white

-perihperal vision is intact

-normal; may be possible temporal pallor ON in cases that are chronic

How is nutritional amblyopia treated?

What are the histological changes?

-vitamin B therapy will usually reverse vision loss

-loss of medulated nerve fibers in the ON, chiasm, and optic tracts corresponding to the papillomacular bundle

-thickening of the connective tissue in the same areas where medulated nerve fibers were destroyed

-degeneration of the ganglion cells of the retina in the area of the macula

What is the cause of toxic organic amblyopia?

What do you expect for the vision?

What is the treatment?

-visual loss cause by exogenous poisions such as methly alcholol, quinine, cocaine, or lead and endogenous poisions such as foca infections and dental infections

-marked loss of central vision with large, dense central scotoma

-remove the cause of toxic amblyopia

What is the cause of organic congenital amblyopia?

What would you expect of the vision?

What would be the maximum VA?

-visual loss attributed to congenital or hereditary abnormalities in the visual pathways and the visual system may fail to form completely

-bilateral, usually associated with other VF defects; color vision deficiencies, ocular albinism, nystagmus

-20/40- 20/60

What are some of the possible causes of congenital amblyopia?

What is the txt of congenital amblyopia?

-malorientation or tilt of the retinal receptors

-some suggest relatively small optic discs-optimal refractive correction

What is psychogenic amblyopia?

What might this also be called?

This is a diagnosis of _______. 

What is the prevalence?

-psychogenic loss of vision due to neurosis of psychosis

-hysterical amblyopia, psychic amblyopia, and functional visual loss

-exclusion

-1% of general population and 5% of optometric population

In what patient is psychogenic amblyopia more common?

What do they complain of?

What is their typical history?

Is is bilateral or unilateral?

What is the typical RE?

-females ages 8-14 yo

- blurry distance vision

-no hx of wearing glasses or vision problems

-almost always bilateral

-small and symmetrical RE (usually hyperopia that is inconsistent with reduced VA)

What do you expect of the binocular findings?

The patient cooperation? Are they malingering?

What might they have in their social history?

How is the ocular health?

How is this usually diagnosed?

What is the txt?

-normal

-good; not malingering

-emotional distress at home/school

-normal

-with tangent screen tubular/spiral fields

-time, counseling, placebo

What is functinal amblyopia?

What patients does this develop in?

-visual loss in which the visual pathway is intact and normal at birth but fails to develop or operate normally due to an abnormality in its stimulus or use

-young patients during the period of visual immaturity

-strabismic amblyopia

-anisometropic amblyopia

-isoametropic amblyopia

-deprivation amblyopia

-idiopathic amblyopia

What causes strabismic amblyopia?

What is the peak age of sensitivity?

What is the mean VA?

What is the median age of presentation?

Is the magnitude of strabismus correlated with the depth of amblyopia?

-VA loss is a consequence of strabismus that is acquired during the period of visual immaturity 

-9 mo to 2 yoa

-20/75; 20/94 with anisometropia

-before 4 yoa

-no

What is the theory behind amblyopia of arrest?

What is the theory behind amblyopia of extinction?

What is the clinical significance?

Is this concept accurate?

-VA will never be better than what it has developed to at the time the strab develops

-deterioration/loss of VA relative to that previously attained, and the loss is recoverable

-only that VA lost due to extinction is recoverable

-clinical evidence suggests this is not the case

Anisometropic Amblyopia is?

How does this reduce VA?

What happens between the better and worse eye?

-loss of VA due to significant refractive error between the two eyes

-blurred image in the higher RE eye and disrupts the normal development of the visual pathway and cortex

-the better eye inhibits the worse eye due to superimposition of the focused and defocused image

What is the mean VA of AA amblyopia?

What is the median age of presentation?

How frequent is SA?

This is associated with what in ___ of cases?

Which eye is this more likely to occur in?

-20/60

-6 yoa

-50%

-strabismus, 50%

-left

In which AA is this more common?

Why is this more common than anisomyopia?

What are the guidelines of amblyopic RE?

Are there exceptions to this?

-hyperopia- >1D

-myopia- > 3D

-astigmatism- > 1.5D

-yes, but they are rare

What amblyopgenic mechanisms are involved in AA?

What percentage of the time is the more ametropic eye amblyopic?

-form deprivation and abnormal binocular interaction

-99%

what is isoametropic amblyopia?

What type of RE is more common?

Why does VA not develop?

What is the BCVA expected to be?

How frequent is this type?

What is the mean age of presentation?

-vision loss due to moderate to high bilateral RE

-hyperopia

-continuously blurry images

-20/30 to 20/70

- ~0.03%

-by about 5 years

What REs are potentially amblyogenic?

Which amblyogenic mechanism is involved?

How is this treated?

-Hyperopia- > 5.00

- Myopia - > 8.00

- astigmatism - > 2.50 

-form deprivation

-give the optimal refractive correction

What is meridional amblyopia?

When does this exist?

Is this unilateral or bilateral?

- selective visual deprivation of visual stimuli of certain spatial orientation caused by uncorrected astigmatism

- when there is a difference in the grating VA between the 2 tested meridians

-could be either

What is deprivational amblyopia?

How debilitating is this condition?

What percentage of amblyopes have this?

Is this unilateral or bilateral?

- visual loss secondary to occurence of a constant phyiscal obstruction along the line of sight that prevents formation of a well focused and high contrast image on the retina

-the most devastating amblyopia

-3%

-can be either

Congenital ptosis will cause deprivational amblyopia in what % of cases?

What is another condition that can cause deprivational amblyopia? This causes what 2 types of amblyopia?

What is a condition that is not usually amblyogenic? Why?

- 18%- 48%

-CN III palsy; strabismic and deprivational

-Marcus-Gunn Jaw Winking (20/40); because the ptosis resolves when the mouth is open

Congenital cataracts

Degree of visual impairment depends on what?

Which cataracts are the most amblyogenic?

The more __ and __ the more visually devastating the cataract.

What tests can show that a cataract is amblyogenic?

-density and location of the cataract

-posterior polar cataract and nuclear cataracts worse than anterior polar cataracts

-posterior and central

when you cannot see a red reflex and when you can not see the fundus due to cataract

What is the critical period to reverse visual loss due to a congenital cataract?

How can doctors cause deprivational amblyopia?

- within 17 weeks, some say at 6 weeks, and others say at 1.8 months

-patching may cause iatrogenic amblyopia

- unilateral= form deprivation adn abonraml binocular interaction

-bilateral= form deprivation only

What may cause idiopathic amblyopia?

Is stereopsis normal? Is txt helpful?

What may transient anisometropia lead to?

-transient congential anisometropia in infancy

- yes; yes

-inhibition of the fovea

Amblyopia summery

Which types of amblyopia are associated with what types of amblyopgenic mechanisms?

-strabismic amblyopia - FD, ABI

-anisometropic amblyopia- FD, ABI

-isoametropic amblyopia- FD

-unilateral cataract- FD, ABI

-bilateral cataract- FD