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methods BLOCK 2 > Entrance test > Flashcards

Entrance test Flashcards

1
Q

Hirschberg test

A
  • rough objective estimate measurement of deviation/strabismus
  • useful in young and cooperative patients
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2
Q

How to do a Hirschberg test

A

A penlight is held straight in front of a patients face at about 50cm. The patient is instructed to fixate on the penlight with both eyes open
-finds if eye is turned out or in

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3
Q

Do you do Hirschberg one eye at a time or two?

A
  • one eye at a time

- observe the position of corneal reflex

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4
Q

3 possible corneal reflexes in Hirschberg

A
  • center of pupil
  • nasal to the pupil
  • temporal to the pupil
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5
Q

Nasal to the pupil

A

positive angle lambda/kappa/ exo posture

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6
Q

temporal to the pupil

A

negative angle lambda/kappa/ eso posture

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7
Q

strabismus

A
  • if the reflexes are not in the same relative position
  • the reflex will not be in the center of the deviated eye and it will be different from the relative angle lambda in that eye
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8
Q

absence of strabismus

A

the corneal reflex should be centered in both eyes

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9
Q

how to determine the amount of deviation

A

for 1mm of estimated deviation, it is approximately a deviation of 22 prism diopters

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10
Q

recording Hirschberg

A
  • indicate that you did Hirschberg
  • if no strabismus, record Ortho or symmetrical
  • strabismus present, record the deviated eye, the size and direction of the deviation

Hirschberg: 44pd LET

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11
Q

Krimsky test

A

-use prisms to determine the angle of deviation seen on Hirschberg test
-not as accurate, only when you can’t perform cover test
-

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12
Q

How to of Krimsky test

A

-prisms are placed in front of the fixating eye until the corneal reflexes are symmetrical

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13
Q

what kind of prism for esotropia?

A

BO

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14
Q

what kind of prism for exotropia?

A

BI

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15
Q

Near Point of Convergence (NPC)

A
  • determines the ability to converge and maintain fusion

- both eyes on one target, ability to read

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16
Q

How to start NPC

A
  • done with correction, good lighting, and start at about 40cm
  • requires transilluminator, red glasses (if they don’t do well), near accomidative target (a 20/30 letter)
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17
Q

How yo do NPC

A
  • tell pt to look at light
  • ask if it is single or double, if double, move target further back
  • move target towards pt while paying attention to eyes
  • move it into the pt until the pt reports double or you see one eye loses fixation
  • move target back again until the pt reports single vision
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18
Q

breakpoint

A

-move the target in until the pt reports double or you see one eye loses fixation, this distance is the break point

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19
Q

recovery

A

Move the target back again until the patient reports single vision or where you notice refutation, measure this distance, this is the recovery

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20
Q

NPC normal findings

A

Break 2.5cm/recovery 5cm, or, TTN (to the nose)

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21
Q

NPC abnormal

A
  • repeat with red glass over right eye (or red green glasses)
  • repeat 3rd time with an accomidative target
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22
Q

What does red/green glasses do for NPC?

A

dissociates what both eyes are doing. Eyes will recede more

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23
Q

convergence insufficiency complaints

A

repeat multiple times, there will be changes in the NPC each time because of fatigue

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24
Q

convergence is closely associated with what?

A

accommodation

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25
Q

What to record for NPC

A
  • sc/cc
  • target used
  • distance (cm) where there was a break or diplopia (from bridge of nose or spec plane)
  • distance of recovery
  • deviated eye and direction
  • diplopia or suppression(break without diplopia)

example
-NPC cc light: TTN
-NPC sc light: 10cm/15cm, OD out, suppression
red/green:15cm/20cm, OD out, suppression
accommodative: 12cm/16cm, OD out, suppression

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26
Q

What can a receded NPC cause?

A
  • binocular vision problems
  • eyestrain/asthenopia
  • reading difficulties
  • difficulties with near point tasks
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27
Q

Amplitude of accommodation

A
  • measures patient ability to accommodate (in diopters)
  • Pt wears correction, near point accommodation target, occluder, illumination
  • MONOCULAR
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28
Q

Push up method

A
  • tell pt to occlude one eye, tell patient to look at a row of letters (one or two lines better than BCVA at N)
  • tell pt to keep the letters clea
  • slowly move the letters closer to the patient, until the patient reports blur
  • measure distance from patient’s spectacle plane in cm and convert to diopters
  • occlude other eye and repeat
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29
Q

near point of accommodation

A

Where it begins blurs when the target is too near to them for them to accommodate

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30
Q

Pull Away method

A
  • Monocular
  • tell pt to keep letters clear
  • hold target very close to pt open eye
  • slowly move letters away from pt, until pt reports clarity
31
Q

How to record Amp of accommodation

A
  • method used (push up or pull away)
  • amplitude of accommodation (D) for each eye

example
Amp of accommodation: 9D OD, 10D OS

32
Q

How close should the readings be for both eyes for Amp

A

within 1 diopter

33
Q

What is expected amp?

A
  • OU within 1 diopter

- accommodation decreases with age, meds, disease

34
Q

Hofsetter’s formula

A

minimum expected amplitude = 15-0.25(age)

You can also use Donder’s table, which basically tells you the same numbers

35
Q

Things that affect accommodation

A
  • age
  • meds (CNS stimulants, tranquilizers, antihistamines, cycloplegics, antidepressants)
  • iridocyclitis
  • trauma
  • alcohol
  • some glaucomas
  • DM, MS
36
Q

Binocular vision

A

-allows us to appreciate many aspects of a target

37
Q

binocular vision and sensory system

A

constructs single perception from 2 retinal images

-achieves single image from both eyes, gives distance of the target

38
Q

binocular system and motor system

A

vergences and eye movements (depth)

  • coordinates the orientation of the eyes in all distances, and on your moving targets
  • coordinates WITH THE ACCOMMODATIVE system to maintain a clear image
39
Q

poor binocular vision leads to

A
  • fatigue
  • eye strain
  • headaches
40
Q

binocular vision is in jeopardy in

A
  • eye disease
  • strabismus
  • trauma (TBI)
41
Q

Little disparity in binocular vision

A

all these systems work well, they give one image from both retinal images and high resolution

42
Q

binocular advantage

A

advantage over monocular vision and monocular clues (depth, more precise, quicker)

43
Q

what is the best indicator of binocularity?

A

stereopsis

44
Q

an indicator of binocularity

A

the sensory and motor fusion of vision; also shows if accommodative and vergences systems are working well

45
Q

Fusion

A

how the eyes unite

46
Q

3 degrees of fusion

A
  1. simultaneous perception and superimposition (1st degree)
  2. flat fusion (2nd degree)
  3. Stereopsis (3rd degree)
47
Q

simultaneous perception and superimposition

A
  • NPC break

- 1st degree

48
Q

flat fusion

A
  • 2nd degree

- NPC recovery, 2 images into 1 (not perceiving depth)

49
Q

stereopsis

A
  • 3rd degree

- to get stereopsis, binocularity has to be excellent to fuse fine disparity

50
Q

purpose of stereopsis

A

to measure fine depth perception by evaluating the ability to fuse stereoscopic targets

51
Q

equipment needed for stereopsis testing

A
  • polaroid glasses (or R/G glasses depending on test)
  • stereo book
  • Pt wears polaroid glasses over near correction
52
Q

what is testing distance for steropsis

A

40cm with overhead light, avoid glare

53
Q

directions for pt for stereopsis

A
  • direct pt to pg 2 with the smallest targets
  • ask which circle is floating
  • ask pt to indentify target in space
  • repeat until pt misses 2 boxes in a row
  • record level of stereopsis
54
Q

If the pt does not appreciate stereo or is unresponsive

A

use medium size targets and repeat

55
Q

if pt identifies all medium size targets on stereopsis..

A

try smaller targets again

56
Q

if pt is not able to correctly identify any of the small or medium targets…

A

show the pt the largest targets

57
Q

How to record stereo

A
  • at near and test used
  • indicate if it was done sc or cc
  • recorded in seconds of arc
  • if none, record no stereo

example
stereo at N cc: 400 seconds of arc, stereo E

58
Q

What is expected stereo at near?

A

20-30 seconds of arc

59
Q

Worth 4 dot

A
  • assess flat fusion
  • detect small central scooter at near (when stereopsis is below normal)
  • cc, R/G over correction, red lens over OD.
  • test can be done at D and at N at 40cm
60
Q

What to tell pt to do for worth 4 dot

A
  • tell pt to look at the W4D target with the red dot on top and the white on the bottom
  • ask how many dots they can see
61
Q

W4D: 4 dots

A

normal fusion

62
Q

W4D: 2 red dots

A

only the red eye is used, OS is suppression

63
Q

W4D: 3 green dots

A

only OS sees, OD suppression

64
Q

W4D: 5 dots

A
  • diplopia

- ask where the red or green dots are located, this determines the location of the visual axis

65
Q

crossed diplopia

A
  • 5 dots
  • 2 red dots are on the left side
  • exo deviation
66
Q

2 red dots on left in W4D with diplopia

A

exo deviation

crossed

67
Q

uncrossed diplopia

A

eso deviation

5 dots, the 2 red dots to the right

68
Q

vertical diplopia

A

it is possible to perceive this. if the red dots are below the green dots, there is a right hyper deviation

69
Q

scotoma

A

dead spot so brain can’t have so much disparity. Brains way of making sure the retina doesn’t see double

  • not physical, brain just shuts it out
  • can still have good stereo and 20/20 VA
70
Q

testing for scotoma

A
  • make sure there is a normal flat fusion with W4D at N.
  • tell pt to look at flashlight and tell you if there is a change to 2 or 3 dots instead of 4
  • slowly move the flashlight away from the pt
  • stop when and if the pt says there is a change in the number of dots. If there is no change in the number of dots at 10ft, stop!
71
Q

When testing for scotoma, if you go all the way to 20ft and there is no change…

A

no suppression

72
Q

if there was a change in testing for scotoma..

A

determine and record which eye is suppressed and at what distance
-ask pt to cover dominate eye, ask if the suppress dots reappear

73
Q

If dots reappear in suppressed eye

A
  • there is a suppression scotoma under binocular conditions

- if they do not reappear, there is a unilateral scotoma

74
Q

how to record W4D

A

W4D: fusion at distance, suppression OD at near
W4D: diplopia, so with right hyper @ N

methods BLOCK 2 (8 decks)

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