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Clinical Skills H > Normal fundus 2 > Flashcards

Normal fundus 2 Flashcards

1
Q

are myelinated nerve fibres (feature of the optic disc) physiological or pathological

A

physiological, but not present on most people

it i non-progressive and benign

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2
Q

when are nerve fibres usually myelinated until

A

not myelinated until the lamina cribrosa

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3
Q

where can nerve fibres sometimes retina their myelin sheaths

A

on the disc or the retina

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4
Q

why are retinal ganglion axons usually unmyelinated as they cross the retina

A

because even though myelin sheaths speed up nerve transmission, if the RGC axons were myelinated across the retina, we won’t be able to see anything as they’re opaque, so it will block the light hitting the retina

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5
Q

what symptoms will a person have if they have myelin sheaths on their retina

A

visual field defect corresponding to there the myelin sheaths are on the retina

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6
Q

what is the appearance of the nerve fibres as a result of myelin sheaths on the retina

A

normally transparent nerve fibres now appear a brilliant white against the fundus background

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7
Q

describe the two layers of capillaries that are over most of the fundus

A
  • a superficial network in the nerve fibre layer close to the vitreous
  • a deep network at the junction on the inner nuclear & outer plexiform layers
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8
Q

where in the retina are no capillaries found

A

central macula

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9
Q

what are the outer layers of the retina e.g. photoreceptors supplied by

A

the underlying choroidal circulation which is not directly visible with the direct ophthalmoscope

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10
Q

what circulation is seen when doing ophthalmoscopy and what does it consist of

A

the inner retinal circulation only, consisting of central retinal arteries & veins which branch out to supply the inner retinal layers & those two capillary networks are found in the retina

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11
Q

what is the appearance of a normal blood vessel wall and what is visible when seen with the direct ophthalmoscope

A

normal walls of bv’s are transparent and only the blood column of the vessels is seen

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12
Q

what is a notable feature of arterioles seen as a reflex in the ophthalmoscope light

A

linear light reflex which is a light following the arterioles

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13
Q

what 2 things is the linear light reflex seen in the arterioles formed by

A
  • reflection from convex, cylindrical blood column
  • reflection from convex vessel wall
  • both surfaces act as convex mirrors
    linear light reflex is more obvious in arteries than veins
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14
Q

what is the purpose of the retinal vessels

A

to supply oxygen and other nutrients from the blood to the 6 inner layers of the retina & take away waste materials

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15
Q

what does the health of the retinal vessels reflect upon

A

the health of the circulation throughout the body

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16
Q

what does examination of the retinal blood vessels assist in

A

detection and monitoring of systemic diseases e.g. hypertension, arteriosclerosis, diabetes

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17
Q

what do arterioles not cross

A

other arterioles

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18
Q

what do venules not cross

A

other venules

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19
Q

what is the normal positions of the arterioles and venules in the retina

A

usually
arterioles remain at normal level in the nerve fibre layer and venule dips to avoid the arteriole, called a/v crossing (artery crossing over vein)

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20
Q

what is the normal appearance of the route of the arterioles and venules at the a/v and v/a crossings in the retina

A

retinal vessels normally curve very gently with no deflections at the a/v and v/a crossings = carry on in their normal directions & don’t look like they’re being squashed

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21
Q

what 2 things does hypersensitive retinopathy cause to the retinal blood vessels

A
  • a/v nipping

- tortuosity (BV’s become wiggly)

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22
Q

how does a/v nipping occur

A

a/v crossing changes are caused, where the underlying venule is compressed by the sclerosed/hardened artery as it crosses over and causes pressure on the vein which gets pinched by the artery

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23
Q

what can a further hardening of the arteriole in the retina cause to the course of the venule

A

may cause deflection of the venule which means it changes directions in right angle

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24
Q

what is a normal cause of tortuous arterioles

A

congenital which should then be uniform across the fundus

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25
Q

what does isolated regions of arteriolar tortuosity suggest

A

sclerosis of arteriole due to high blood pressure

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26
Q

what do pathological changes to the arterioles cause to their appearance

A

causes arteriole narrowing

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27
Q

what do pathological changes to the venules cause to their appearance

A

an increase in width

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28
Q

what does pathological changes in vessel calibre (thickness) cause to the a/v ratio

A

it gets altered to e.g. 1/4 or 1/5

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29
Q

what is a normal a/v ratio considered to be

A

2/3

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30
Q

how are you supposed to check the a/v ratio in order to detect change in vessel calibre

A
  • chose vessels of comparable order of branching i.e. vessels that branch by the same amount
    e. g. if artery we’re looking at has branched twice since the optic disc, then compare that with a vein thats branched twice since the optic disc
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31
Q

what naturally happens to the vessel calibre of all the vessels the further away they get from the disc

A

get narrower the further away from the optic disc

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32
Q

what two things must you look for when detecting abnormal changes e.g. from hypertension in vessel calibre (thickness)

A
  • focal narrowing

- generalised narrowing to arterioles (severe narrowing in the case of hypertension)

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33
Q

when is mild generalised narrowing of the arteriole normal

A

found in a healthy elderly fundus

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34
Q

what does focal narrowing of the vessels look like

A

a patch of narrowing of changes of vessel thickness as you go along

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35
Q

what is leakage of a vessel a sign of

A

pathology

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36
Q

what 3 things are shown in a fundus when a blood vessel leaks

A
  • hard exudates (lipids)
  • haemorrhages (blood)
  • oedema (fluid e.g. plasma or serum)
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37
Q

what is oedema fluid e.g. plasma or serum viewed in a OCT scan as

A

dark patches within the reflective layers

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38
Q

which imaging technique is oedema hard to view

A

in fundus photography, may see a bit of swelling

39
Q

in a healthy eye, what is the only non visible part of the vessel

A

the part of the vessel (e.g. of a venule) that is obscured by an arteriole at an a/v crossing

40
Q

by what 2 things may a vessel be obscured in a non usual way

A
  • myelinated nerve fibres
    or
  • pre retinal haemorrhages obscures the retina
41
Q

how does a inner retinal haemorrhage occur

A

when the inner circulation has bled into the vitreous cavity

42
Q

name 3 causes of hyperplasia of pigment in the retina

A
  • choroidal naevus
  • malignant choroidal melanoma
  • congenital hypertrophy of the RPE - CHRPE
43
Q

what is a choroidal naevus

A

a harmless area of increased pigment of the choroid

44
Q

what colour does a choroidal naevus appear

A

uniform slate grey or brown colour

45
Q

what shape does a choroidal naevus appear

A

round or oval

46
Q

how large are most choroidal naevus

A

less than 3 disc diameters in diameter

47
Q

how deep is a choroidal naevus and how can you tell this

A

flat or minimally elevated, blood vessels passing over will stay in focus & not change course

48
Q

what can also be spotted on top of a choroidal naevus

A

overlying drusen speckled on top of it (white spots)

49
Q

what must you note down when looking at the retina as seen by the ophthalmoscope

A

any pigment deposition seen in retina

50
Q

is a choroidal naevus dangerous

A

no it is benign and won’t cause any problems to the patient at all

51
Q

what causes a choroidal naevus

A

accumulation of melanocytes in the choroid

52
Q

what is the cause of a malignant choroidal melanoma

A

a cancerous tumour which can metastasise = life threatening

53
Q

what colour and appearance is a malignant choroidal melanoma

A

ranges in colour from white to greenish grey and has a mottled appearance

54
Q

how large is a malignant choroidal melanoma

A

often larger than a naevus >3 disc diameters

55
Q

if a malignant choroidal melanoma is larger than 3 disc diameters in size, what 2 things can this cause

A
  • a serous retinal detachment

- disrupts transport between fluid & RPE

56
Q

how deep is a malignant choroidal melanoma and how can you tell this

A

significantly elevated
ophthalmoscope will go out of focus as it passes over it and the blood vessels also goes higher as the melanoma acts as a bridge so it looks like the blood vessels are changing direction

57
Q

what may be found overlying a malignant choroidal melanoma

A

orange pigment = lipofuscin

58
Q

what symptoms are presented with a malignant choroidal melanoma

A 
often asymptomatic, but may present with:
- metamorphopsia 
- photopsia 
- visual field defect
- hypermetropic shift 
all of which disrupt vision
59
Q

what action must be taken when seeing a malignant choroidal melanoma

A

urgent referral

60
Q

what is congenital hypertrophy of the RPE (CHRPE) caused by

A

congenital hyper pigmentation of the RPE

61
Q

what appearance of congenital hypertrophy of the RPE (CHRPE)

A

a flat black lesion with sharply remarked outline, darker than a naevus

62
Q

what is also frequently seen around congenital hypertrophy of the RPE (CHRPE)

A

ring of hypo pigmentation

63
Q

is congenital hypertrophy of the RPE (CHRPE) dangerous

A

no it is benign

64
Q

what must you do to monitor a congenital hypertrophy of the RPE (CHRPE)

A

take a photo to monitor and make sure it doesn’t change size

65
Q

what is the appearance of a coloboma of (retina) choroid

A

large, white oval lesion in fundus, benign, non-progressive appearance of retina

66
Q

what is the appearance of a coloboma of (retina) choroid

A

large, white oval lesion in fundus, benign, non-progressive appearance of retina, can see right through to sclera underneath

67
Q

where abouts is a coloboma of (retina) choroid usually found in the retina

A

usually inferior nasal region

68
Q

what is a coloboma of (retina) choroid a result of

A

failure of the embryonic fissure to close = missing part of retina

69
Q

can a coloboma of (retina) choroid affect one or both eyes

A

can be unilateral or bilateral

70
Q

what symptoms may a px with coloboma of (retina) choroid experience

A

visual field defect corresponding to the missing part of retina e.g. superior temporal VF defect if the coloboma is at the inferior nasal region of fundus

71
Q

what other visual problem may a px with coloboma of (retina) choroid have

A

px is often amblyopic

72
Q

how far away is the centre of the macula from the optic disc

A

1.5 - 2 disc diameters away

73
Q

where is the macula located in the fundus

A

temporal to and slightly lower than the disc

74
Q

what is the shape of the macula

A

oval with the long axis horizontal

75
Q

how large is the macula

A

a bit larger than the optic disc ~20 degrees diameter

76
Q

where is the macula entered on

A

the fovea

77
Q

where does the colour of the macula come from

A

accumulation of macula pigment

78
Q

what component of the fundus does not permeate around the macula

A

blood vessels

79
Q

what is the name of a macular reflex

A

foveal reflex

80
Q

what is the appearance of a normal foveal reflex

A

bright spot of light at centre of fovea

81
Q

what is the only real landmark on a healthy macula

A

bright foveal reflex

82
Q

how is a macular/foveal reflex formed

A

by an image of the ophthalmoscope beam formed by the concave surface of the fovea (foveal pit), acting as a concave mirror

83
Q

what can someone with early ARMD go on to get

A

dry or wet stages

84
Q

what stages can someone with early ARMD go on to get

A

dry or wet stages

85
Q

what dos early stages of ARMD show

A

extensive drusen

86
Q

what is drusen

A

pockets of the RPE layer

87
Q

what characteristic signs on the retina does wet AMD cause

A

exudates and haemorrhages of the blood vessels

88
Q

what does dry AMD cause

A

death/atrophy of the retina & RPE in that area of the macula, causing a complete scotoma corresponding to the atrophy, also called geographic atrophy

89
Q

what characteristic signs of the retina does dry AMD cause

A

can see through to underlying choroid where retina & RPE have died away

90
Q

what is toxoplasmosis caused by

A

a parasite

91
Q

what are the symptoms of toxoplasmosis if its in the periphery

A

none

92
Q

what is the appearance of an inactive toxoplasmosis

A

sharply defined edges & pigmented

93
Q

what are the symptoms of toxoplasmosis if its on the macula

A

complete scotoma

94
Q

what is the appearance of an active toxoplasmosis

A

it means the parasite is still there, and has more of inflammation & pigmentation comes in a later stage

Clinical Skills H (18 decks)

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