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2nd Sem > P2 - Orthoptics > Flashcards

P2 - Orthoptics Flashcards

1
Q

are fast, ballistic eye movements that abruptly change the point of fixation

A

Saccadic system

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2
Q

what are the eye movement systems

A

Saccadic system
Smooth pursuit system
Vergence system
Vestibulo-ocular movements

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3
Q

Saccadic System

include willed refixations, those in response to command and memory-guided saccades

A

Voluntary movements

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4
Q

Saccadic system

include saccades in the direction of a new stimulus that may be visually guided (prosaccade) or in response to an auditory stimulus, accompanied by head movement in the same direction

A

Reflex movement

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5
Q

Saccadic system

After onset of a target saccade it takes (latency) about how many millisecond for eye movement to begin

A

200ms

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6
Q

Saccadic system

Maximum velocity is up to

A

500°/s

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7
Q

are much slower tracking movements of the eyes designed to keep moving stimulus on the fovea

A

Smooth Pursuit System

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8
Q

under voluntary control in the sense that the observer can choose whether or not to track a moving stimulus

A

Smooth pursuit system

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9
Q

It is one of the two ways that visual animals can voluntarily shift ggaze, the other being Saccadic eye movements

A

Smooth pursuit system

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10
Q

What is the stimuli in smooth pursuit system

A

fixated targets that moves across the foveal and perifooveal retina

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11
Q

tested by placing a subject inside a rotating cyl with vertical stripes (subject is seated in front of a screen on whoch a series of horizontally moving vertical bars is presented to conduct this optokinetic test)

A

Smooth pursuit system

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12
Q

is a normal reflexive response of the eyes in response to large-scale movements of the visual scene & should not be confused w pathological nystagmus that can result from kinds of brain injury

A

Optokinetic Nystagmus

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13
Q

Maximum speed of OKN

A

90°/sec

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14
Q

Latency of OKN

A

125 ms

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15
Q

can be elicited voluntarily, but occur reflexively whether the eyes are open, even when fixated on a target

A

Saccadic system

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16
Q

small movements made while reading

A

Saccadic system

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17
Q

rapid eye movements that occur during an important phase of sleep

A

Saccadic sytem

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18
Q

much larger movements made while gazing around a room

A

Saccadic system

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19
Q

under both volitional and reflex control

A

Saccadic system

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20
Q

are disjugate and smooth where one eye can move independently of the other

A

Vergence system

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21
Q

occur as synkinesis with accommodation of the lens & pupillary constriction

A

Vergence system

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22
Q

What rectus muscles are innervated during vergence movements

A

Medial & Lateral Recti motorneurons

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23
Q

may occur as Saccadic or Smooth pursuit movements, and therefore cortical areas relating to generation of these eye movements will be involved in the cortical proceesing of visual information

A

Vergence eye movements

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24
Q

Vergence system maximum velocity

A

20°/sec

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25
Vergence system latency
160ms
26
what is the stimuli of vergence system
disparity between location of images on the retina of each eye, resulting in fusional vergence & retinal blur caused by loss of focus of images, which results in accommodative vergence
27
stabilize the eyes relative to the external world, thus compensating for head movements
Vestibulo-ocular movements
28
reflex response prevent visual images from "slipping" on the surface of the retina as head position varies
Vestibulo-ocular movements
29
can be appreciated by fixatiing an object and moving the head from side to side
Vestibulo-ocular movements
30
intergrates eye and body movements and is not dependent on ocular stimulation but is concerned with head position & balance
Vestibulo-ocular movements
31
Vestibulo-ocular movements maximum speed
90°/sec
32
Vestibulo-ocular movements latency
15ms
33
the false localisation of objects in space in px with recent paresis due to sensory changes resultimg from alterned alignment of the eye
Past-pointing
34
Left LR paralyzed and OS attempts (OD is occluded) to look at an object to the left, that object will be thought to be located further to the side than it actually is)
Past-Pointing
35
VA: Visual perception of an object is resolved according to:
1. light sense 2. form sense 3. form sense
36
is the absolute threshold of light
Light sense
37
what are the two Form Sense
Central vision Peripheral vision
38
is inclusive of VA and Contrast sensitivity
Form sense
39
the ability to discriminate fine high contrast detail
Central vision
40
the field of vision
Peripheral vision
41
Variables that affect VA | (RECCO)
1. Retinal stimulation 2. Contrast 3. Eye movements 4. Contour interaction 5. Occlusion
42
central stimulation involves the fovea with higher acuity function, luminance (brightness of target)
Retinal stimulation
43
sensitivity to background lighting
Contrast
44
even when looking steadily at tragets there are constant refixation movements to maintain central fixation
Eye movements
45
it is easier to identify a target presented singly than one with other surrounding stimuli
Contour interaction
46
this may be by hand, atropine, high plus lens, blenderm, opaque (glasses, opaque patch, opaque occluder or Spielmann occluder)
Occlusion
47
what are the Qualitative Clinical Vision Tests
- Fixation - Cover test - Visually directed-reaching - 100s & 1000s - Catford drum - Stycar Rolling/Mounted balls - Ten Dioptre Prism - Mirror test
48
# Qualitative test observe pursuit movement and fixation preference
Fixation
49
# Fixation Fixation preference detects what if the deviation exceeds 10 prism dioptres
Amblyopia
50
What is the fixation preference in the presence of strabismus
it may show equal alteration, fixation held through a blink, fixation held briefly, fixation held with difficulty or no fixation held with stabismic eye
51
uniocular fixation & objection to occlusion
Cover test
52
reaction to visual stimulus by reaching towards the object of interest
Visually-directed reaching
53
response to small sweets & indicates acuity of approximately 6/24
100s & 1000s
54
- moving dots or gratings - fast saccades - for infants and preschool
Catford drum
55
- graded balls in various sizes mounted/rolled along floor - pursuit eye movements
Stycar rolling/Mounted ballss
56
assess fixation preference in preverbal children who are not strabismic or who have small deviations
Ten Dioptre Prism
57
In 10D prism, it is recommended that the prism be held ____ in cases of ptosis to aid accuracy in detecting eye movement response
Base up
58
- performed base down or base up - a 25-dioptre base-in prism may also be used
Ten Dioptre Prism
59
the infant is held close to a mirror so that they can look at their own reflection
Mirror test
60
- the distance of the infant from the mirror is increased until they no longer look at themselves - this test is useful as it is portable and easy to administer
Mirror test
61
what are the Quanttitative clinical vision tests (FTNPCC)
- Forced Choice Preferential Looking Cards (FCPL) - Teller Acuity Cards - Near test - Pinhole - Crowding phenomenon - Contrast sensitivity
62
the test cards consists of a black & white grating placed on the left or riight of the card
FCPL
63
the observer records the direction of head movements in response to the appearance of striped stimulus
FCPL
64
VA determined with FCPL range
Newborns: 6/240 3 months: 6/60 36 months: 6/6
65
introduce a set of 16 cards that consisted of a grey background with a square wave grating on on side
Teller Acuity Cards
66
process is undertaken at a testing distance of 38 or 55cm. Eye movements are observed towards the position of the stripes
Teller Acuity Cards
67
What are the Near Tests
- Reduced Snellen test - Reduced Sheridan Gardiner - Reduced E test - Maclure book - Moorfields bar reading book - N series test
68
used to assess whether or not reduced vision is caused by uncorrected refractive error
Pinhole
69
when vision improves this is indicative of refractive error, if no improvement occurs, there is amblyopia, or some organic cause for reduced vision
Pinhole
70
easier to see a single optotype than a letter on a linear chart
Crowding phenomenon
71
the reduced VA is due to the additional stimuli from surrounding letters & results in confusion
Crowding phenomenon
72
specifically caused by contour interaction and attentional factors, this is noted in particular with reduced VA in amblyopes
Crowding
73
the ability to distinguish between different levels of contrast
Contrast sensitivity
74
uses sine waves, continuous waveforms that oscillate in smooth & regular manner and can be of diff freqiencies and amplitudes
Contrast sensitivity
75
# Contrast sensitivity it is the number of cycles per degree: one cycle includes one dark and one light area
Spatial frequency
76
condition when tthe eye deviates from parallelism when fusion has been broken
Heterophoria

2nd Sem (3 decks)

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