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X. Strabismus > Introduction/Evaluation > Flashcards

Introduction/Evaluation Flashcards

1
Q

___% of strabismus patients develop amblyopia

A

50%

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2
Q

What percentage of patients whose chief complaint is an eye turn actually have strabismus?

A

50%

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3
Q

Incidence of strab in children

A

3-4%

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4
Q

What magnitude of deviation is found in infantile ET?

A

35-40 ∆

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5
Q

Age of onset for Infantile ET

A

Birth to 6 months

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6
Q

Age of onset for Accommodative ET?

A

2-3 yrs

when toddler begins exploring near world

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7
Q

In the first few months of life, infants come exhibit variables amount of strab.

What magnitude and at what age is this finding normal and thought to resolve over time 25% of the time?

A

< 30 ET between 3-6 months will resolve 25% of the time

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8
Q

Characteristics of an eye turn

A

FLORIDA

Frequency
Location
Onset
Relieving Factors
Intensity
Direction
Associations

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9
Q

A premature baby is born before ____

A

37 weeks

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10
Q

What is a low birth weight?

A

< 1500 g or 3.3 lb

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11
Q

What is an abnormal APGAR score?

A

≤ 6

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12
Q

APGAR score is based on

A
  1. Skin color
  2. Pulse rate
  3. Reflex response
  4. Muscle tone
  5. Breathing
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13
Q

Birth History pertinent to Strab/Amblyopia (6)

A
  1. Premature birth
  2. Low birth weight
  3. Low APGAR score
  4. Prenatal morbidity
  5. Substance abuse/smoking
  6. Older maternal age
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14
Q

What is considered an older maternal age?

A

> 30 years old

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15
Q

Developmental Hx pertinent to Strab/Amblyopia

A
  1. Craniofacial anomalies
  2. Neurodevelopmental impairment
  3. Down Syndrome
  4. ROP
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16
Q

2 Ways to Assess Amblyopia Treatment Prognosis

A
  1. 2.0x Telescope
  2. Neutral Density Filter
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17
Q

Amblyogenic Factor: Isometropia Astigmatism

A

> 2.5 D

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18
Q

Amblyogenic Factor: Isometropia Hyperopia

A

> 5 D

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19
Q

Amblyogenic Factor: Isometropia Myopia

A

> 8 D

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20
Q

Amblyogenic Factor: Anisometropic Astigmatism

A

> 1.5 D

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21
Q

Amblyogenic Factor: Anisometropic Hyperopia

A

> 1 D

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22
Q

Amblyogenic Factor: Anisometropic Myopia

A

3 D

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23
Q

UCT determines

A

Presence/absence of strabismus

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24
Q

ACT determines

A

Direction and magnitude

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25
Q

Testing distance for Hirschberg/Krimsky

A

50-100 cm

26
Q

Testing Distance for Bruckner

A

75-100 cm

27
Q

3 reasons for false positives in Bruckner

A
  1. Anisocoria
  2. Significant Anisometropia
  3. Unilateral media opacity
28
Q

4 Tests to assess Ocular Alignment

A
  1. CT
  2. Hirschberg/Krimsy
  3. Bruckner
  4. 4 BO Test
29
Q

Why are objective tests more appropriate to test ocular alignment than subjective tests?

A

Pt may have developed anomalous correspondence

30
Q

4 BO Test:
Prism placed in front of the left eye and there is no movement. What is the result? Does this confirm a microET?

A

(+) 4 BO Test OS

No, 4 BO Test does not confirm the presence of a strab; it only confirms presence of suppression.

31
Q

4 BO Test:
Prism placed in front of right eye
Both eyes move the the left
Left eye then moves to the right
What is the result?
What happens if you switch the prism to the other eye?

A

(-) 4 BO Test OD, OS

Same results; a version followed by a duction confirms suppression in neither eye

32
Q

RECTUS muscles insert at a ___º angle and ____ the equator

A

20º
In front of

33
Q

OBLIQUE muscles insert at a ___º angle and ____ the equator

A

50º
Behind

34
Q

Hering’s Law are in reference to ____ (synergists/antagonists)

A

Synergists

35
Q

Sherrington’s Law are in reference to ____ (synergists/antagonists)

A

Antagonists

36
Q

In a palsy of ____ onset, secondary deviation is larger than primary. Why?

A

RECENT; Hering’s

37
Q

Primary deviation is measured when which eye is fixating? (Affected/Unaffected)

A

Unaffected

38
Q

Secondary deviation is measured when which eye is fixating? (Affected/Unaffected)

A

Affected

39
Q

3 Reasons for EOM underaction/overaction

A
  1. Innervation deficiency (CN 3, 4, or 6)
  2. Mechanical reasons (faulty muscle insertion restricting movement)
  3. Paretic EOM (e.g. trauma)
40
Q

What is the difference between an ocular torticollis and congenital torticollis?

A

Ocular torticollis — head tilt due to visual issue (resolves w/ correction)

Congenital torticollis — abnormal head/shoulder mm.

41
Q

(+) Forced Duction Test means…

A

The eye did NOT move —> mechanical (e.g. muscle entrapment)

42
Q

(-) Forced Duction Test means…

A

Muscle was able to move —> innervational issue

43
Q

3 Tests to test Comitancy

A
  1. Hess Lancaster
  2. CT in 9 Gazes
  3. Red Lens Test in 9 Gazes
44
Q

Parks 3 Step must always be conducted when ___

A

Presence of vertical deviation

45
Q

What are the 3 steps in Parks Three Step?

A
  1. Which is hyper in primary gaze
  2. Which gaze makes the deviation worse?
  3. Which head tilt makes the deviation worse?
46
Q

Why must you perform retinoscopy monocularly?

A

An eye turn will cause a pt to appear more myopic

47
Q

TRUE/FALSE: unsteady fixation is seen in both CF and EF

A

TRUE

48
Q

Rank these in order from Best VA to Worst VA:
1. Steady CF
2. Unsteady CF
3. Steady EF
4. Unsteady EF

A

Best VA
|
1. Steady CF
2. Unsteady CF
3. Unsteady EF
4. Steady EF
|
Worst VA

49
Q

3 tests to assess Fixation

A
  1. Brock After Image
  2. MIT
  3. Visuoscopy
50
Q

Formula for determine approximate VA for EF

A

VA = 20 / [20(1+PD)]

Example: 3 PD EF
20 ( 1+3 ) = 80
Estimated VA: 20/80

51
Q

What (in the retina) causes Haidinger’s Brush?

A

Xanthophyl in Henle’s Layer (around the fovea)

52
Q

MIT:
OD is occluded
OS is open
OS views brush 2 cm left of fixation
What is the EF?

A

2 PD temporal EF

53
Q

Which eye is flashed during Brock After Image?

A

NON-amblyopic eye

54
Q

TRUE/FALSE: Patients will mild amblyopia may still have stereopsis

A

TRUE

55
Q

First Degree Fusion

A

Superimposition — can perceive two dissimilar targets as occupying same visual direction

56
Q

Second Degree Fusion

A

Flat Fusion — fusion w/o stereopsis

57
Q

Third Degree Fusion

A

Stereopsis

58
Q

Horror Fusionis

A

Inability to fuse two images —
Approaching targets seem to slide of jump without apparent fusion or suppression

59
Q

W4D:
Why might a patient that suppresses OS (sees 2 red dots only) at a distance of 6 m, perceive fusion when retested at 33 cm?

A

At 6m, suppression zone is larger than target angle

At 33 cm, the target angle is larger than the suppression zone

60
Q

TRUE/FALSE: size of suppression zone is independent of room lighting

A

FALSE

61
Q

TRUE/FALSE: pts often develop both suppression and AC

A

TRUE

62
Q

Name 2 tests of motor fusion

A
  1. BI/BO range
  2. NPC

X. Strabismus (6 decks)

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