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clinical skills > visual field defects? where is the pathology? > Flashcards

visual field defects? where is the pathology? Flashcards

1
Q

how do you instruct your patient ?

A

> This test will test all the area you can see with each eye
I want you to always look straight ahead at the fixation light in the centre ( show them)
other lights will now flash in different places. Every time you see a light press your button
You will not see all the lights
the most important thing to remember is to always keep watching the fixating light in the centre

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2
Q

How to improve accuracy with your patient?

A

: ensure they are comfortable

  • neck/ head position
  • coat on or off

: explain how long it will take
-xx no of minutes

: patient can cause pause the test on a humphrey

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3
Q

define visual field defect?

A

A visual field defect is defined as a departure from the topography of the hill of vision from normal limits

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4
Q

why is it important to accurately describe type of visual field defect?

A

helps to determine the type of pathology

Helps to monitor the condition

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5
Q

what is contraction of visual field?

A

defect starts from peripheral to inside

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6
Q

what is depression or diffuse visual field loss?

A

a generalised reduction in the height of the hill of vision

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7
Q

what is localised defect?

A

small area of defect

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8
Q

what are defects called in visual fields?

A

Scotoma

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9
Q

How can Scotoma be classified?

A 
Area of vision loss 
margins 
shape of defect 
central  visual field 
baring of the blind spot
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10
Q

what type of scotomas with area vision loss do you get?

A

A. Absolute

B. Relative

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11
Q

what does absolute defect mean?

A

can see
can see
cannot see anything

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12
Q

What does relative defect mean ?

A

Can see , can see little,
cant see much
cannot see at all

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13
Q

what type of scotoma margins do you get?

A

A. Steep

B. Sloping

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14
Q

what does steep margins of scotoma look like?

A

from normal to not seeing nothing

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15
Q

What does sloping margins of scotoma look like?

A

from normal to little bit less to nothing at all seen

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16
Q

what type of shape defect to you get?

A 
Hemianopia 
Altitudinal Hemianopia
Macula sparing 
Macula splitting 
quadrantanopia
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17
Q

what does hemianopia look like?

A

Half of visual field not seen

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18
Q

What does altitudinal hemianopia look like?

A

superior or inferior loss of visual field

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19
Q

What does macula sparing defect look like?

A

visual field defect but macula is spared

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20
Q

What does macula splitting defect look like?

A

Half of the macula has defect ( macula split in half)

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21
Q

what does quadrantanopia defect look like?

A

a quadrant of the visual field cannot be seen

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22
Q

what type of central visual field are there?

A 
Central scotoma 
Pericentral Scotoma 
Paracentral Scotoma 
Centrocecal Scotoma 
Nasal step
Arcuate scotoma 
Ring scotoma
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23
Q

What is central scotoma?

A

scotoma in the centre of visual field effecting the fixation point on the fovea

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24
Q

What is pericentral Scotoma?

A

ring of defect surrounds the fixation point fovea but does not effect the fovea

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25
Q

What is paracentral scotoma?

A

Adjacent to fixation point fovea not surrounding it

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26
Q

What is centrocecal scotoma?

A

Extends from fixation point to blind spot

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27
Q

what is baring of the blind spot?

A

defect leaves the blind spot out

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28
Q

what is nasal step scotoma?

A

classic glaucoma defect that 1st effects nasal side and will not cross the horizontal midline

29
Q

what is arcuate scotoma?

A

defect that arcs around from the blind spot

30
Q

What is ring scotoma?

A

Defect ring around the visual field

31
Q

what does homonymous hemianopia mean?

A

Half of the same side of visual field loss

32
Q

What does Bi temporal hemianopia mean?

A

Half of temporal side of each eye visual field loss

33
Q

What types does Homonymous hemianopia are there?

A

> Partial
Complete
Macula sparing

34
Q

What is partial hemianopia?

A

defect does not come to midline

35
Q

what does complete hemianopia mean?

A

defect comes all the way up to midline

36
Q

What does the macula sparing hemianopia mean?

A

half of visual field lost but macula is spared

37
Q

What is bi nasal hemianopia?

A

Both nasal half of visual field has been lost

38
Q

what is congruous defect?

A

same shape and size defect with symmetry in both eyes

39
Q

what is incongruous defect?

A

Defect that is not same size, shape or symmetry in both eyes

40
Q

Define localisation?

A

Knowledge of the arrangement of the nerve fibres in the visual pathway will enable you to localise the visual field defect

41
Q

What are the superior Temporal Fibres projected by in visual field?

A

superior temporal fibres project in inferior nasal visual field

42
Q

What are the superior Nasal Fibres projected by in visual field?

A

superior nasal fibres projected in the inferior temporal visual field

43
Q

What are the inferior Temporal Fibres projected by in visual field?

A

inferior temporal fibres projected in the superior nasal visual field

44
Q

What are the Inferior Nasal Fibres projected by in visual field?

A

Inferior nasal fibres projected in the superior temporal fibres

45
Q

What is nasal step?

A

the Fibres at the rim are the most crowded at the disc providing less structural and vascular support and are the most likely to become damaged in glaucoma

fibres from inferior rim supply the inferior temporal retina damage to this area corresponds to superior nasal visual field defect.

The areas supplied by the fibres corresponds to the nasal step and do not cross the horizontal raphe

46
Q

What are the rules for visual field assessment?

A

Retinal lesions can be :
unilateral or bilatera
often asymmetrical between eyes
do not respect the verticle midline

47
Q

what do macular fibres do?

A

Macular fibres cross

48
Q

What do nasal fibres do?

A

Nasal fibres cross

49
Q

What do temporal fibres do?

A

Temporal fibres uncrossed

50
Q

what does unilateral field defect involve?

A

involves damage to anterior to the chiasm

51
Q

what does a field which respects the vertical meridian suggest?

A

chiasmal or posterior to chaism damage

52
Q

what do you get if damage is at the chiasm?

A

you get heteronymous defect

53
Q

what do you get if the damage is before chiasm?

A

You get anterior unilateral defect

54
Q

What do you get if the damage is after the chaism?

A

You get field defect that starts to respect vertical midline

55
Q

What type of defect do you get with post chiasm?

A

Homonymous defect

56
Q

what do you get with chiasmal defect?

A

Heteronymous

57
Q

If damage is above the inion?

A

You get scotoma in inferior Visual Field

58
Q

If the damage is below the inion?

A

You get scotoma in the superior Visual Field

59
Q

How much doe the V1 relate to the macula?

A

60%

60
Q

If pathology is in the left cerebral hemisphere?

A

The scotoma was on the right

61
Q

If the pathology is in the right cerebral hemisphere?

A

The scotoma was on the left

62
Q

Where do you get incongruent ?

A

incongruent optic tract

63
Q

Where do you get congruent?

A

Congruent towards occipital lobe

64
Q

what happens to anterior lesion?

A

spares the macula

65
Q

what does unilateral field loss suggest?

A

Unilateral field loss not likely to be neurological ( anterior to the chiasm )

66
Q

What does bilateral defect suggest?

A

post chiasm and respects the midline

67
Q

Does the field loss respect the vertical meridian?

A

Suggests chiasmal or retrochiasmal

68
Q

what factors do you look at in glaucoma defects?

A

Paracentral scotomas
Enlargement of the blind spot
Nasal step
Arcuate scotomas

clinical skills (13 decks)

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