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Clinical Skills H > Normal fundus 1 > Flashcards

Normal fundus 1 Flashcards

1
Q

define the fundus

A

the interior of the globe as seen with the ophthalmoscope e.g. the retina, optic nerve head, macula

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2
Q

what is the limit of the fundus i.e. where the retina joins the ciliary body

A

ora serrata

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3
Q

which components of the eye join at the ora serrata

A

retina joins the ciliary body at the equator of the eye

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4
Q

how much of visualisation of the fundus does direct ophthalmoscopy allow

A

65-70%

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5
Q

what technique allows a full 100% view of the fundus

A

scleral indentation (can see all the way around into the periphery) is an instrument to press onto the side of the eyeball = pushing the fundus into view of the direct ophthalmoscope

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6
Q

which two things does the orange/red background of the fundus as seen from the pupil come from

A

light directly reflected from choroidal blood vessels/blood in the choroidal circulation

light that is reflected back from the sclera and transmitted through choroidal blood vessels

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7
Q

what is the chorio capillaris

A

dense network of choroidal capillaries & is a dense blood supply

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8
Q

what layers does light shone into the eye go through

A

the transparent retina, through the RPE & to the choroid,
light reflected back from the blood in the choroid that gives the retina its orangy glow & some light goes through the choroid and bounces back off the sclera

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9
Q

what two things does the amount of light directly reflected from the choroidal blood vessels and transmitted through the choroidal blood vessels depend on

A
  • degree of pigmentation of the retina

- degree of pigmentation of the choroid & RPE

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10
Q

what type of appearance does a fundus where there is a lot of pigment between the ophthalmoscope and choroidal blood supply have

A

brown & dim

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11
Q

what is the condition of most of the fundus/retinal layers in a healthy eye

A

transparent and do not contribute to the fundus appearance all we see is the blood vessels in the retina

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12
Q

what retinal layer does contribute to a typical fundus appearance

A

internal limiting membrane = between the retina & vitreous

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13
Q

what appearance does the internal limiting membrane layer of the retina have

A

appearance of watered silk/shiny especially in younger people and it reflects the ophthalmoscope beam

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14
Q

what are the three different types of normal fundus which are just physiological differences between people

A
  • uniform stippled
  • tesselated (tigroid)
  • albinotic
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15
Q

what are the three types of uniform stippled types of fundus appearance

A
  • dark or negroid
  • medium or caucasian
  • light or blonde
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16
Q

what does a uniform stippled fundus look like

A

like its made up of lots of little dots or coloured, looking speckled

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17
Q

what is the two reasons of a dark or negroid appearance of a fundus

A
  • heavily pigmented RPE

- heavily pigmented choroid

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18
Q

what is the two reasons of a medium or caucasian fundus appearance

A
  • normally pigmented RPE

- normally pigmented choroid

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19
Q

what is the two reasons of a light or blonde fundus appearance

A
  • lightly pigmented RPE

- lightly pigmented choroid

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20
Q

what does the light pigmentation of the RPE and choroid in a light or blonde fundus result in, in its appearance

A
  • bright glow from choroid & able to see individual choroidal blood vessels which appear bit fatter and blurrier
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21
Q

what is the two reasons of a tessellated or tigroid fundus appearance

A
  • lightly pigmented RPE
  • normal to heavily pigmented choroid
    so can see through the RPE as it hasn’t got much pigment, but the choroid underneath has lots of pigment
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22
Q

what is the reason for a albinotic fundus appearance

A

virtually no pigment in RPE or choroid, can see through layers of the choroid and RPE and can see blood vessels of underlying choroidal circulation

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23
Q

what 4 things does the degree of pigmentation in the retina depend on and explain whether the degree of pigmentation is uniform across the whole retina

A
  • age
  • race
  • hereditary
  • metabolic
    you can have more than one type of fundus background in the same eye, degree of pigmentation of retina & choroid don’t always run parallel
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24
Q

define the optic disc

A

the ophthalmoscopic view of the optic nerve head

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25
Q

what are the 7 main features of the optic disc

A
  • size
  • shape
  • colour
  • margins
  • level
  • vessels
  • surroundings
26
Q

what 2 things does the colour of the optic disc depend on

A
  • the white lamina cribrosa and myelinated nerve fibres behind the lamina
  • the red blood (around the optic disc rim) in capillaries supplying the disc
27
Q

why is it harder to detect glaucoma in a small optic disc

A

as a small disc has a small cup to disc ratio therefore the RGC axons are more bunched up (usually a big cup to disc ratio is expected to be seen in a glaucomatous patient)

28
Q

what does a pink rim around the disc indicate

A

a healthy optic disc as there are lots of tiny capillaries giving a good blood supply

29
Q

what is the appearance of a deeper cup

A

the more paler it looks as you are looking more into the lamina cribrosa

30
Q

why is the cup in the centre of the disc more pale

A

as you are looking at a more deeper level in the optic nerve head, seeing through to the lamina cribrosa & myelinated nerve fibres underneath,
so the deeper the cup, the paler it looks in the ONH

31
Q

what is the appearance of the margins on a healthy disc

A

relative blurring of margins on nasal 2/3rds of the disc

32
Q

what can sharp clear margins on the nasal side of the disc indicate

A

optic atrophy

33
Q

what can very blurred margins on the temporal side of the optic disc indicate

A

oedema (swelling of the disc)

34
Q

what can be the causes of a swollen disc/papilloedoema and how does it appear in volk and direct ophthalmoscopy

A 
raised intracranial pressure from:
- aneurysm 
- haemorrhage 
- space occupying tumour 
volk - disc looks raised & swollen
direct ophthalmoscopy - bf's look clear but disc looks blurry
35
Q

what can be the causes of a swollen disc/papilloedema

A

raised intracranial pressure from:

  • aneurysm
  • haemorrhage
  • space occupying tumour
36
Q

how many % of eyes have a flat disc

A

15%

37
Q

how can the level of cupping be measured

A

by recording the vertical C/D ratio

38
Q

what does a cup depth which goes more deep overtime indicate

A

glaucoma as they are losing RGC’s overtime

e.g. if 0.2 CD ratio in 20’s then 0.5 CD ratio in 50’s = pathological

39
Q

what cup to disc ratio is susceptible to glaucoma

A

0.6

40
Q

what does a cup depth which goes more deep overtime indicate

A

glaucoma as they are losing RGC’s overtime

41
Q

what is visible in deeper cups

A

lamina cribrosa

42
Q

how does the lamina cribrosa appear as in very deep cups

A

a granular structure

43
Q

what can be observed at the boundaries of the cup when assessing the cup depth

A
  • look at colour change

- the small bv’s skirt around the edge of the cup

44
Q

explain which 2 ways you will detect changes in level of cup depth with a handheld direct ophthalmoscope

A
  1. quantitative:
    - the difference in the lens required for focusing
    e.g. edge of disc is clear with plano, but the bottom of the cup is first clear with a -3D lens
    = depth of cup is 3D
    - a shallow cup will be at the same level as the rim, so don’t need to change lens power as much
  2. parallax (qualitative)
    - when moving the ophthalmoscope beam
    - areas at different levels move at different speeds
    - deep cup = more movement
45
Q

which 2 blood vessels enter through the optic disc cup

A
  • central retinal vein

- central retinal artery

46
Q

describe the central retinal artery

A

CRA has all characteristics of a true artery, but after branching soon becomes an arteriole

47
Q

describe the central retinal vein

A

CRV has all characteristics of a true vein but after branching soon becomes a venue

48
Q

what is the usual pressure of the central retinal vein

A

2mmHg higher than mean IOP

49
Q

explain why and how spontaneous pulsation of the central retinal vein occurs

A
  • CRV pressure is usually constant - 2mmHG higher than mean IOP
  • during cycle of variation of IOP = the IOP will become greater than the CRV pressure
  • this leads to partial collapse of the vein, which will not recover until IOP falls back below that in the CRV
50
Q

what is the reason for characteristic surrounding of the optic disc

A

certain layers of the fundus stopping short of the disc

51
Q

list 3 characteristic surroundings of the optic disc

A
  • scleral ring
  • choroidal crescent
  • pigment spots
52
Q

how does a scleral ring occur

A

RPE & choroid stop short of the disc and only the sclera reaches the ONH = pale ring around disc

53
Q

what can a scleral ring cause visually and why

A

larger blind spot as px has no rods or cones here

54
Q

how does a choroidal crescent occur

A

RPE stops short of the disc causing a pigmented ring around the disc and the sclera and choroid reach/go to the disc

55
Q

which group of people can a scleral ring occur in

A

myopic patients who have large axial lengths

56
Q

how/why do pigment spots occur around the optic disc

A

build up of more than the usual amount of pigment at the edge of the disc

57
Q

where does the cilio retinal artery come from

A

it is not a branch of the CRA, but is derived from blood vessels supplying the choroid, i.e. from underlying choroidal circulation

58
Q

how large is the cilio retinal artery

A

varies in size, but can be as large as a principle arteriole

59
Q

what does the cilio retinal artery supply

A

significant area of the retina

60
Q

how is having a cilio retinal artery beneficial

A

if get a central retinal artery occlusion, you won’t go blind as the cilio retinal artery will supply the retina and you will still have an island of vision left

Clinical Skills H (18 decks)

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