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VS III > Abnormal Visual Development: Amblyopia > Flashcards

Abnormal Visual Development: Amblyopia Flashcards

1
Q

Amblyopia is a disease of ______. It is a unilateral/bilateral condition in which the best corrected VA is poorer than 20/20 in the absence of any obvious structural anomalies or ocular disease

A

exclusion

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2
Q

Amblyogenic factors is a disease of ______. Amblyopia is always associated with strabismus, anisometropia, an episode of image deprivation or a combination of the 3 early in life usually before age 6/8

A

inclusion

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3
Q

The prevalence of amblyopia ranges from ____% to _____ % depending on the population studied and the definition used.

A

1.6; 3.6

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4
Q

Amblyopia effects all aspects of vision including:

A
  1. Reduced CS and visual resolution.
  2. Inc sensitivity to contour interaction (crowding)
  3. abnormal spatial distortions and uncertainty
  4. unsteady/inaccurate monocular fixation
  5. inaccurate accommodative response.
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5
Q

Amblyopia is categorized by ____ amblyopia, ____ amblyopia, ____ deprivation amblyopia, or it could be idiopathic.

A
  1. refractive: anisometropic/isometropic
  2. strabismic
  3. form (congenital cataract)
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6
Q

Isometropia refers to both eyes having similar ______ error and both eyes having very high rx.

A

refractive

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7
Q

Amblyogenic refractive error due to anisometropia is due to having astigmatism of greater than _____ D, hyperopia of greater than _____ D, and myopia greater than ____ D.

A

1.50; 1.00; 3.00

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8
Q

Amblyogenic refractive error is due to having isometropia when astigmatism is greater than ____ D, hyperopia of greater than _____ D and myopia is greater than _____D.

A

2.50; 5.00; 8.00

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9
Q

Amblyogenic strabismus could be constant vs intermittent, unilateral vs alternating, distance, near/both, or onset before ____years old

A

8

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10
Q

In order for amblyopia to be in full effect, it has be ____, it can’t be alternating at distance/near, it can’t be just at _____

A

constant, not intermittent; near

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11
Q

In order for us rule out form deprivation we need to ask about:

A
  1. congenital/traumatic cataract
  2. early complete blepharoptosis (one eye’s visual axis blocked)
  3. corneal opacity
  4. hyphema
  5. vitreous hemorrhage
  6. iatrogenic (if patch good eye too much)
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12
Q

_____ form deprivation is the worst form.

A

monocular

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13
Q

Binocular form deprivation includes:

A
  1. Dark rearing
  2. Binocular lid suture
    - VS remains normal and ready to recover with visual experience.
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14
Q

Binocular congenital cataracts cause very mild amblyopia, if removed at 4-6 months of age, VA will be around ____ OU, relatively longer critical period

A

20/50

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15
Q

In monocular deprivation we see structural changes in LGN, there is a smaller size of neurons in layer ____. You also see neuronal shrinkage in deprived parvocellular layers secondary to the striate cortex.

A

A1

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16
Q

Monocular congenital cataracts causes severe amblyopia. If removed at 4-6 months of age, VA will be ____. You have to remove it before ____ months. Deprived can recover up to ____

A
17
Q

The 2 most common forms of amblyopia are:

A
  1. Strabismic

2. Anisometropic

18
Q

In Strabismic and anisometropic amblyopia there are no structural changes in visual cortex and LGN. They have less profound loss in _____, and usually have better VA.

A

CSF

19
Q

Why is monocular form deprivation the most severe form of amblyopia?

A
  1. See structural changes in LGN.
  2. Worse VA
  3. shorter critical dev period
  4. reduced CSF
  5. Happens in all spatial frequency
20
Q

____ amblyopes often have no CSF loss, but if they do its at high spatial frequencies. _____ amblyopes always have a CSF loss at _____ spatial frequencies, and almost always at have a very small loss at lower frequencies.

A

Strabismic; Anisometropic; high

21
Q

Isometropic amblyopes have BCVA of greater than or equal to _____ but show wide range from slightly worse than 20/20 to 20/200

A

20/50

22
Q

Bilateral high hyperopia can cause 3 scenarios:

A
  1. Accommodative esotropia: infant accommodates well and has normal AC/A ratio
  2. Bilateral refractive amblyopia: child maintains binocularity by underaccomodating
  3. Normal vision: infant accommodates well and has low AC/A ratio
23
Q

In myopic isometropic amblyopia, the CSF has equal sensitivity loss at all _____ ____

A

spatial frequencies

24
Q

Meridional amblyopia is induced by high astigmatism and has ____ VA loss

A

mild; develops later due to the presence of astigmatism over a period of years.

25
Q

In anisometropic amblyopia and in normal vision, you see the biggest loss in ____ region. ____ amblyopia shows nasal/temporal asymmetry.

A

foveal; strabismic

26
Q

What are factors that affect the degree of crowding?

A
  1. Sep between the characters
  2. character size
  3. location in the visual field
27
Q

Crowding phenomenon is normal for everyone if it is happening in the ____ retina. Amblyopia is happening in central foveal region.

A

peripheral

28
Q

Amblyopic reading deficit is affected mainly by increased ____ effect, rather than reduced VA. VA with ____ letter yields the best VA

A

crowding; isolated

29
Q

Possible neural mechanism as to why amblyopes suffer from spatial misperception could be due to neural ____ in the orientation and spatial frequency domains native to the primary visual cortex. Confused _____ detectors may also explain how these different patterns occur.

A

undersampling; line

30
Q

Fixation for _____ amblyopes is usually central and _____. Fixation for _____ amblyopes is usually eccentric and _____

A

anisometropic; unsteady

strabismic; eccentric (instead of using fovea they use peripheral point to fixate)

31
Q

Strabismic amblyope eyes usually have from ____ to ____ degrees of eccentric fixation and is measured by maxwell spot or visuoscopy.

A

0.5; 4

32
Q

Describe how the Maxwell spot measurement is done

A

Utilizes specific pigmentation around central foveal region causing an entopic phenomenon. It’s seen using a cobalt blue filter and is accentuated by first bleaching retina with a green light. The central few degrees will appear darker than periphery. After staring at blue screen and open dot for 15 sec and switching to yellow screen you should see a white spot which means you have central fixation. For strabismic puts they see white spot off to the side.

33
Q

How does visuoscopy work?

A

You use an opthalmascope with the bulls eye target to look at patients foveal light reflex in patients bad eye, while they are covering their good eye. Normal pt’s will have foveal light reflex at center of bulls eye. Strabismic patient’s will have light reflex moving around. They will have nasal eccentric fixation.

34
Q

Accommodation appears to be reduced secondary to amblyopia. Pt will experience unsteady and inaccurate accommodation. They will experience high ____ and a lot of ____ motion

A

lag; with

VS III (7 decks)

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