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PPO 1a > Lecture Four > Flashcards

Lecture Four Flashcards

1
Q

define functional vision

A

ability to focus and coordinate the two eyes comfortably for visual tasks especially at near.

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2
Q

failure to treat binocular abnormalties could result in?

A

amblyopia

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3
Q

is amblyopia preventable? what percent of children have it in US?

A

yes

1-4%

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4
Q

Define binocular

A

the use of both eyes simultaneously such that each retinal image contributes to the final perception

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5
Q

what are the two categories of binocular problems?

A
  1. binocular vision is maintained but is stressful and uncomfortable ( called phoria)
  2. Binocular vision is absent (strabismus)
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6
Q

What are two types of fusion?

A
  1. sensory: ability to combine sensory information for each eye into a single image
  2. Motor fusion: ability to align both eyes and maintain alignment.
    one cant happen without the other.
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7
Q

what are some tests that can test for sensory fusion?

A

worth 4 dot and stereopsis

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8
Q

what are some tests that can test for motor fusion?

A

hirschberg, bruckners, cover test and krimsky

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9
Q

Does motor and sensory fusion occur separately or simultaneously?

A

simultaneously but tested separately.

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10
Q

Reasons why we are binocular?

A
  1. spare eye
  2. larger field of view
  3. defects in on eye often masked by the normal eye
  4. some perceptions are better with two eyes i.e. VA
  5. MAJOR REASON= stereopsis
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11
Q

what is stereopsis?

A

perception of depth

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12
Q

What two types of stereopsis do we use?

A

monocular and binocular cues. monocular used for far away things, binocular used more for up close.

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13
Q

What are the three prerequistes needed for binocularity?

A
  1. two eyes that function normally and equally
  2. retinal image to OD and OS must be the same size, illuminance, location in space and color (sensory fusion)
  3. the eyes must be capable of aligning so that retinal images of a fixated object can be placed and maintained on the fovea of each eye (motor fusion)
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14
Q

what does a functional entrance binocularity test tell us?

A

if the patient has normal sensory and motor fusion. if not which prereq is missing

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15
Q

What is a local sign?

A

tells us where things are located in space relative to one another and ourselves. It is innate and is a cortical process.

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16
Q

Objects located in nasal space will be reflected on which retina (for right eye)? temporal space? when eye is looking straight ahead what part of retina is this focused on?

A

temporal retina.
nasal retina
fovea (in normal eyes).

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17
Q

What are corresponding points?

A

pairs of points (one being in each eye) that have the same visual direction and sned their nerve impulses to the same point in the same visual cortex and give rise to sensory fusion.

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18
Q

Objects imaged on corresponding points are seen what if patient has normal sensory fusion?

A

binocularly.

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19
Q

What cortex does the fovea go to in each eye?

A

both cortexes at the same time

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20
Q

Example of a corresponding point?

A

nasal point in right eye, temporal point in left eye, both going to the same cortex.

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21
Q

what is a non corresponding point?

A

a point in one eye with another point in the other eye that are not going to the same cortex.

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22
Q

What happens when we get stimulation of non corresponding points? what do small amounts lead to?

A

large amounts of retinal disparity which can lead to diplopia.
small amounts of retinal disparity lead to stereopsis

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23
Q

What is physiological diplopia? how does it happen?

A

normal diplopia, occurs in patients with binocular vision.

happens by looking at two non fixated objects who images are stimulated on non corresponding points.

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24
Q

What are the four types of sensory fusion?

A
  1. Simultaneous perception (seeing an image with each eye at the same time i.e. dog and pig)
  2. Superimposition (1st degree fusion): seeing two images and localizing them in the same place i.e. face in window
  3. Flat fusion (2nd degree): combining two images with some similar detail and some non similar detail i.e. worth 4 dot
  4. Stereopsis (3rd degre fusion): perception of depth, patient combines two images into a single one that has depth.
25
Q

Worth four dot:
Red lens goes on which eye? green lens? testing distance? white dot orientated where? ask patient what? what is the normal response?

A

Right eye, left eye, 40cm, white dot on bottom. how many dots do you see? normal response is 4.

26
Q

if patient says they see 5 dots in worth 4 dot, what do you ask?

A

where are the two red dots? where are the 3 green dots? ( eyes are not aligned)

27
Q

if patient sees just two red dots what is happening?

A

suppression of OS

28
Q

if patient sees just 3 green dots what is happening?

A

suppression of OD

29
Q

If red dots are to the right and green are to the left what do we have? if red dots are to the left and green dots are to the right?

A 
uncrossed diplopia (eso, one eye turned in)
crossed diplopia (exo, eye turned out)
30
Q

if red dots are up and green dots are down? if red dots are down and green dots are up?

A 
left hyper (OS higher than OD)
right hyper (OD higher than OS).
31
Q

Normal recording for worth 4 dot?

A

worth 4 dot @40cm fusion

32
Q

What is always associated with vertical deviation?

A

a direction, right or left.

33
Q

Some people will see 4 dots but there eyes are clearly not aligned (determined in externals) why?

A

sensory adaptation, NOT sensory fusion. called anomalous retinal correspondence.

34
Q

Uncrossed diplopia gives what kind of eye turn?

A

esotropia

35
Q

Crossed diplopia gives what kind of eye turn?

A

Exotropia

36
Q

If red are up and green are down?

A

Left hyper (OS higher than OD)

37
Q

If green are up and red are down?

A

Right hyper (OD higher than OS)

38
Q

Left hyper is the same as?

A

right hypo.

39
Q

how many responses are possible on worth 4 dot?

A

7

40
Q

Who sees 5 dots in the worth 4 dot test?

A
  1. strabismus: misalinged eyes (most people with strabismus will not see 5 dots they will suppress one eye i.e. 2 red dots or 3 green dots)
  2. phoria: patients who have normal fusion under normal circumstances but cant maintain fusion when wearing glasses.
41
Q

When we detect an anisocoria, what has to be determined?

A

whether it is physiological or acquired (pathological)

42
Q

What are some crucial things to check to see if anisocoria is physiological?

A
  1. has been there for a while, previous photos
  2. no ptosis
  3. no EOM abnormalties
  4. Normal responses to light (D&C)
  5. Asymmetry the difference between the pupil sizes should be the same in dim and bright light.
43
Q

what percent of people have an anisocoria? what is the normal difference in size?

A

20%

greater than or equal to 0.4mm

44
Q

If anioscoria is pathological what must be determined?

A

which pupil is abnormal

45
Q

If the difference between pupil sizes is bigger in bright light than that in dim light which eye is the bad one?This is due to what type of an effect? if there were ptosis or EOm abnormalties in this condition what could this mean?

A

one with large pupil.
parasympathetic efferent pathway defect.
damage probably closer to ciliary ganglion.

46
Q

If the difference between pupil sizes is bigger in dim light than that in bright light which eye is the bad one? this is due to what type of defect?

A

one with the smaller pupil.

sympathetic pathway defect: dilation lag.

47
Q

two examples of diseases that can occur when we have the difference in pupil sizes bigger in bright light than in dim light?

A
  1. Adies Tonic Pupil: most common, in younger aged women usualy 20-40, no ptosis, no EOM abnormalties.
  2. CN3 palsy: abnormal EOMS, ptosis occurs in the eye with the larger pupil, pupil end up facing down and out. if pupil doesnt function normally this is another type of CN3 palsy where it could be an angorism (usually patient has a headache, GO TO EMERGE).
48
Q

Example of a disease of anisocoria when the difference in pupil size is greater in dim light than bright light?

A

Horner’s syndrome: miosis, mild ptosis in the eye that has the smaller pupil.

49
Q

Does a +RAPD cause anioscoria?

A

NO

50
Q

What two muscles does CN3 innervate in the inferior division?

A

ciliary body (accommodation) and iris sphincter muscle.

51
Q

What nerve affects pupils, EOMs and accommodation?

A

CN3

52
Q

Superior division of CN3 affects what muscles?

A

SO and levator palpebral superioris.

53
Q

In CN3 palsy which muscles work?

A

only SO and LM (because they are not innervated by this nerve) therefore only up and down works.

54
Q

What is duction?

A

movement of one eye along one axis. horizontal: supraduction (up), infraduction (down). Vertical axis: abduction (out) or adduction (in).

55
Q

What are vergences? 2 types are?

A

movement of both eyes in opposite directions.

convergence: both eyes moving in
divergence: both eyes move out

56
Q

What is version movement? examples?

A

movement of both eyes by same distance and in same direction.

dextroversion: both eyes looking to the right
levoversion: both eyes looking to left
supraversion: both eyes looking up
infraversion: both eyes looking down

57
Q

If strabismus is found in a patient what must be determined?

A

whether it is comitant or non comitant.

comitant: the eye turn is the same in all positions of gaze, can be determined by hirschberg during EOM movements (5PD)

58
Q

what is hypertropia?

A

one eye deviated upwards.

PPO 1a (11 decks)

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