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Clinical Skills Year 2 > visual fields lec 1: kinetic perimetry > Flashcards

visual fields lec 1: kinetic perimetry Flashcards

1
Q

what is the definition of a visual field

A

all the space that an eye can see at any given time

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2
Q

how far does the visual field extend superiorly

A

60 degrees

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3
Q

how far does the visual field extend inferiorly

A

75 degrees

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4
Q

how far does the visual field extend nasally

A

60 degrees

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5
Q

how far does the visual field extent temporally

A

100 degrees

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6
Q

what is the visual field limited by

A

facial features/anatomy e.g. forehead, eyebrows, nose, cheek bones

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7
Q

what is considered the central visual field

A

30 degrees inside

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8
Q

what is considered the peripheral visual field

A

30 degrees outside of the central visual field

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9
Q

what does every point on the retina correspond to in the visual field

A

a certain direction in the visual field

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10
Q

where does the nasal retina project

A

temporally

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11
Q

where does the temporal retina project

A

nasally

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12
Q

which orientation will the visual field be in relation to the retinal image on the eye

A

upside down and front to back

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13
Q

if theres a problem with the inferior nasal retina, where will the visual field defect be

A

the superior temporal visual field

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14
Q

which part of the fundus has the highest threshold sensitivity and why

A

the fovea, because it contains the highest density of cones

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15
Q

which part of the fundus has no threshold sensitivity

A

the optic disc = blind spot

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16
Q

what happens to threshold sensitivity as you go away from the fovea and why

A

threshold sensitivity reduces, as cone density reduces

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17
Q

at which side of the visual field is the physiological blind spot and why

A

temporal visual field, as the optic disc is always at the nasal retina

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18
Q

how wide is the physiological blind spot

A

5.5 degrees wide

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19
Q

how far from fixation is the physiological blind spot

A

15 degrees

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20
Q

how high in the visual field is the physiological blind spot

A

7.5 degrees

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21
Q

how much below the midline is the physiological blind spot

A

1.5 degrees below

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22
Q

which side will the physiological blind spot be on the right eye

A

right hand side

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23
Q

which side will the physiological blind spot be on the left eye

A

left hand side

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24
Q

which side will a patient’s right fundus be to the clinician

A

always on the clinicians left side

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25
Q

which side will a patient’s left fundus be to the clinician

A

always on the clinicians right side

26
Q

what is the measurement of visual field called

A

perimetry

27
Q

what are the two types of perimetry

A
  • kinetic
    and
  • static
28
Q

what does the inside of the hill of vision represent

A

what you can see

29
Q

what does the outside of the hill of vision represent

A

what you can’t see

30
Q

what does the height of the hill of vision represent

A

the threshold

31
Q

what are the two types of manual kinetic perimetry

A
  • gross perimetry

- golmann perimeter

32
Q

list the steps of how you will carry out manual kinetic perimetry

A
  • stimulus moves from where the px can’t see it, to where they can see it
  • plot this onto a map
  • stimulus is a fixed size and luminance
  • eccentricity that the stimulus is seen as is then recorded at every 15 degrees, totalling 360 degrees
  • points of equal sensitivity form together to make an isopter
  • one isopter is not enough, so different isopters are measured using different stimulus sizes or light intensities
  • to measure more closer to the centre fov, the procedure is repeated with smaller/lower luminance stimulus
  • a minimum of 3 isopters is required for a good contour map of the visual field
33
Q

what type of manual kinetic perimetry is gross perimetry

A

a gross screening test

34
Q

list the steps of how to carry out gross perimetry

A
  • px faces practitioner
  • occlude one eye
  • px told to constantly fixate on examiner’s nose
  • target held at 35cm from the patient’s eye, outside the fov
  • px report when they are first aware of the target
  • carried out in uniform surroundings if possible
  • target is moved at a constant velocity and in a imaginary arc
  • once the px notices the target, make a mental note of it and continue moving the target to the centre, to see if they have a scotoma
  • repeat in the 8 directions of gaze
  • repeat with the other eye
35
Q

list the 8 directions of gaze which gross perimetry must be carried out in

A
  • superior
  • superior temporal
  • temporal
  • inferior temporal
  • inferior
  • inferior nasal
  • nasal
  • superior nasal
36
Q

where must the patient constantly fixate when carrying out gross perimetry

A

examiner’s nose

37
Q

at which distance is the target held from the patient with gross perimetry

A

35cm

38
Q

list 4 advantages of gross perimetry

A
  • quick
  • cheap
  • only method possible with young children or elderly with stroke
  • detects gross field defects
39
Q

list 4 disadvantages of gross perimetry

A
  • useless for small areas of vision loss
  • no control of stimulus luminance or contrast
  • no control over background
  • recognition of defect is dependent on judgement of practitioner
40
Q

where is the goldmann perimeter mainly used

A

in hospitals for kinetic perimetry

41
Q

list the components of a goldmann perimeter and state how to use it

A
  • projector
  • head and chin rest
  • response button (px presses when they see target)
  • target - luminance and size controls can be specified (better than gross perimetry)
  • chart to draw isopter plots on
  • pantoscopic arm (moves stimulus around)
  • chin rest positioning (can move around to get the red light on the fovea)
  • occlude one eye
  • adjust the chin/head rest so the patients eye is in the centre of the telesope’s field
  • instruct the patient (to push the button when they just see the target)
  • put up correct refractive correction
42
Q

when will you always give a reading correction when carrying out perimetry

A

when measuring the inside 30 degrees of visual field

43
Q

what makes up the reading correction

A

distance correction + reading addition

44
Q

when will you not need to use a correction when carrying out perimetry and what is the exception to this

A

when measuring the outside 30 degrees of visual field

unless the px has a +/- 8.00 DS refractive error

45
Q

for a full goldmann perimetry when and when not can spectacles be used and why

A
  • specs can be used inside 30 degrees
  • specs not used outside 30 degrees
    because the rim gets in the way
46
Q

what lens will you give when carrying out perimetry on a 60 year old px whose normal near add is +3.00D and distance rx is plano

A

+3.00D lens

47
Q

what lens will you give when carrying out perimetry on a 60 year old px whose normal near add is +3.00D and distance rx is -3.00D

A

give nothing

48
Q

what lens will you give when carrying out perimetry on a 60 year old px whose normal near add is +3.00D and distance rx is +3.00D

A

+6.00D lens

49
Q

what is the near addition on the goldmanns table of near addition for a 40-44 year old

A

+1.50DS

50
Q

what is the near addition on the goldmanns table of near addition for a 45-49 year old

A

+2.00DS

51
Q

what is the near addition on the goldmanns table of near addition for a 50-54 year old

A

+2.50DS

52
Q

what is the near addition on the goldmanns table of near addition for a 55 or year old or a cyclopeged px

A

+3.00DS

53
Q

list the 7 steps of how to use the goldmann bowl perimeter

A
  • select a stimulus e.g. v3
  • move the stimulus in from the periphery, non-seeing to seeing
  • record what they can see
  • continue to move the stimulus to the centre, asking the patient to report if it disappears (to see any scotomas further in)
  • repeat at 15/30 degrees intervals (30 degrees is adequate)
  • repeat for atleast two other stimulus size/luminance combinations
  • repeat these steps for the other eye
54
Q

how does goldmann perimetry with octopus help with which settings should be used for which aged patients

A

it has aged matched normal values, for immediate judgement of normality i.e. landings tells you what should be used for what age

55
Q

how is goldmann perimetry with octopus good at being a repeatable test

A

it has automatic repetition and follow up of kinetic examinations i.e. stimulus moves at the same speed. with a follow up button

56
Q

how is the quantification of goldmann perimetry with octopus

A

measurement of isopters for the quantification of progression

57
Q

which two types of kinetic testing does goldmann perimetry with octopus have

A

manual or automatic

58
Q

list 3 advantages of kinetic perimetry

A
  • useful for detecting contraction of visual fields e.g. in retinitis pigmentosa
  • useful for detecting neurological problems e.g. large visual field defects are detected such as a hemianopia
  • useful in young children when automated versions are not possible
59
Q

list 6 disadvantages of kinetic perimetry

A
  • requires a skilled operator with manual perimetry
  • results are operator dependent with manual perimetry
  • difficult to quantify results with manual perimetry
  • children/adults with a stroke will find manual perimetry easier (gross perimetry) as they move you can pause
  • poor sensitivity for detecting scotomas with both manual and automated
60
Q

what refractive correction will you use on a patient who has less than 1D of cyl

A

mean sphere/BVS (sph + 1/2 cyl)

61
Q

when will you insert a cyl when carrying out perimetry

A

if the patient’s cyl is above 1DC

Clinical Skills Year 2 (20 decks)

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