Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

cs > examining the fundus part 2 > Flashcards

examining the fundus part 2 Flashcards

1
Q

what are the various characteristics we will be looking at when observing the optic disc ?

A
  • observe the disc colour and shape
  • notice that blood vessels appear from the disc and progress to all regions of the fundus
  • observe the region where the blood vessels originate that is the optic cup
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is the optic cup ?

A

the cup is the central region of the optic disc from which the blood vessels emerge , often paler than the rest of the disc

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what is the optic disc ?

A

the disc is the wide , round region , paler than the surrounding fundus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what some structures in the optic disc ?

A
  • neural retinal rim - nerve axons transmitting signals from the retina to the brain
  • lamina cribrosa -
  • at bottom of optic cup
  • nerve axons leave the retina through pores in connective tissue . these are often visible , especially in deep optic cup , but also in the more shallow cup
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

how to assess the neural retinal rim ?

A
  • ## red-free filter ( green ) filter on ophthalmoscope may be helpful with assessing neural retinal rule
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what is the ISN’T rule ?

A

ISN’T rule states that the neural retinal rim should be thickest in the inferior part of the optic disc then in the superior part of optic disc then in the nasal part of optic disc then in the temporal part of optic disc

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what are observations you should be making when assessing neural retinal rim ?

A

. Should be smooth, regular and intact 360 degrees
. Look for notches (bites) and variation in hue( colour)
. Compare both eyes – the rim
appearance should be similar
.ISN’T rule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what else do we assess when examining the optic disc ?

A

the cup:disc ration

C:D ratio

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what id C:D ratio ?

A

ratio of height of optic cup compared to height to height of optic disc

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what are the clues you can use to assess what the CD ratio is and where the cup begins within the disc ?

A
  • The optic cup is
    often pale relative
    to the surrounding disc ( pallor )
  • remember the pale region does not necessarily coincide with the cup
  • more accurate method :look at where the blood vessels start to kink within the optic disc
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what is the significance of a large CD ratio ?

A
  • sign of glaucoma
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what are the variable aperture sizes in direct ophthalmoscope ?

A
  1. large aperture
  2. medium aperture
  3. small aperture ( macular stop)
    - reduces field of view
    - reduces reflections significantly
    - increases Px comfort
  4. slit
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what are the variable filters in direct ophthalmoscope ?

A
  1. fixation
  2. blue light
  3. red free light
    - increases contrast between red regions and background
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

how does red-free filter in direct ophthalmoscope work ?

A
  • same purpose as the green filter on a slit-lamp
  • when we have something red ( i.e. some blood on the fundus )
  • when we shine white light onto that red surface , The surface absorbs all but the long wavelengths, so we see it as red.
  • The green filter absorbs long
    wavelengths and transmits everything else.
    The green filter blocks long wavelength light comes from the red surface, so we
    see this as black.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

how does fixation target work in an ophthalmoscope ?

A

• The patient and the practitioner can both see this target.
• To check whether the patient is using central (foveal) fixation: let
the patient look directly at the centre of the target and observe whether the fovea is in the centre of the target.
• Non-central fixation can explain poor visual acuity in some patients, and may be secondary to other causes of poor acuity in
others.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what is the function of slit aperture in the ophthalmoscope ?

A

• The slit aperture in the ophthalmoscope may be helpful to examine contours and assess the depth of findings in fundus

. A slit of light becomes deviated when it illuminates a surface that is not flat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

why is it hard to assess depth using indirect ophthalmoscope ?

A

• No ‘stereoscopic’ (binocular) viewing of fundus so depth is
not easy to assess

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what is another way of assessing depth on ophthalmoscope ?

A
  • by using focus
  • if an area is completely flat and we shine our ophthalmoscope , if area is flat the whole area should be in focus
  • if there is some depth , the area we’re focused on will not be in focus
  • cup will be further away from us then optic disc as its dipped and will be out of focus
  • we can change focus wheel on ophthalmoscope to see what we need to change focus by to get that part of image into focus

when looking at wheel

  • More +power indicates more anterior or elevated (closer to you)
  • More – power indicates more posterior or depression (further from you)
  • In general 1D ~ 1/3mm i.e. ~3 D/mm
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what is another technique of assessing optic cup depth ?

A
  • by assessing how pale the cup
  • deeper cup = much paler
  • shallow cup = lee pale
20
Q

how to know you have a haemorrhage in front of retina ?

A
  • haemorrhage conceals the retinal blood vessels

- this means that the haemorrhage is in front of the retina

21
Q

how do you know when you have a lesion behind the retina ?

A
  • we can see the retinal blood vessels

- what we’re looking at is behind the retina

22
Q

what is a final way you can assess depth with a direct ophthalmoscope ?

A
  • by using motion parallax
    • Reveals apparent displacement of objects against the background if
    ophthalmoscope is moved laterally
    • Objects in front of (Anterior to) P (your point of focus) will produce Against movement
    • Objects behind P will produce With movement
23
Q

how do we know where an opacity or lesion is with respect to iris ?

A

we know where iris is and we got some opacity or lesion and we want to know where that is in relation to iris we can focus on the iris then move the ophthalmoscope whilst looking through it and see what direction the opacity or lesion moves in relation to the iris

  • objects in front of whatever you’re focused on will produce an against movement
  • objects behind your point of focus = with movement
24
Q

what can you see at the optic disc margin ?

A
  • possible to see different coloration around optic disc margin
  • hyper-pigmentation of disc margins - dark colouration
  • hypo-pigmentation of disc margins - lighter pigment
25
Q

what is choroidal crescent ?

A
  • a common form of hyper-pigmentation - dark colouring all way round or part all the way round the optic disc margins
  • choroidal crescent - choroid extends all the way to the optic nerve head
  • the retinal pigment epithelium which lies between the choroid and retina doesn’t extend all the way to optic nerve head
  • so when looking through an ophthalmoscope you are able to see through the retina all the way to the choroid
26
Q

what is scleral crescent ?

A
  • neither retinal pigment epithelium nor choroid extend to the optic nerve head
  • the sclera is visible as a relatively pale region
27
Q

what are the characteristics of scleral or choroidal crescents ?

A

•Asymptomatic
- No visual loss

•Generally isolated findings

  • Associated with
  • High myopia
  • ‘Tilted disc’
  • ONH margins harder to recognise
  • No treatment
28
Q

explain the appearance of lamina cribrosa ?

A
  • Visibility should be noted
  • The ‘cribiform plate’ is a region of collagenous connective tissue
  • Sieve-like
  • Provides support to nerve axons located here
29
Q

when is lamina cribrosa most visible ?

A
  • Commonly visible
  • More often seen with large C/D ratios
  • More visible with age and nerve fibre loss (e.g. in glaucoma)
30
Q

what is some features you should look for in optic disc ?

A

1 - Cilio-retinal Artery

About 1 in 5 people have this.

It branches from the ciliary
circulation and supplies the
macula and the optic nerve.

31
Q

what happens if there is a blockage in the central retinal artery and you have cilio - retinal artery ?

A
  • the central retina including the macula can become starved of oxygen as the blood supply is cut off
  • the presence of cilio-retinal artery provides an additional blood supply to macula , thus saving your sight
32
Q

what are some other features of the optic disc ?

A

Myelinated nerve fibres:

These are nerve fibres (or
axons) with myelination,
which should be absent
from the retina. The
myelinated region has a
corresponding visual field
defect (vision is lost in
that region).
33
Q

what is myelin ?

A

white , fatty insulating layer around the nerve fibre

34
Q

where does the central retinal artery and central retinal vein branch from ?

A 
• The central retinal artery and the central retinal vein
branch from the ophthalmic
artery and come into the eye
through the optic nerve
head. Each then branches
from the optic nerve head to
serve four main quadrants of
the retina.
35
Q

what is the function of retinal vessels ?

A

provide blood supply for the inner two thirds of the retina

36
Q

what are the 4 main quadrants of the retina ?

A
  • superior nasal retina
  • superior temporal retina
  • inferior nasal retina
  • inferior temporal retina
37
Q

how do central retinal vein and central retinal artery split ?

A
  • central retinal vein and central retinal artery split or bifurcate in the retina into different blood vessels to supply the different quadrants of the retina
38
Q

explain the bifurcation of retinal vessels ?

A

1st bifurcation : CRV ( central retinal vein )emerges at optic disc and splits into SRV ( superior retinal vein ) and IRV ( inferior retinal vein )

2nd bifurcation :
. SRV splits into SNV ( superior nasal vein ) and STV ( superior temporal vein )
. IRV splits into INV ( inferior nasal vein ) and ITV ( inferior temporal vein

3rd bifurcation

.SNV splits again
. STV splits again
. INV splits again
.ITV splits again

same for CRA

39
Q

what are the 6 retinal veins / artery visible when examining the retina ?

A
  • superior retinal vein/artery
  • inferior retinal vein/artery
  • superior nasal vein/artery
  • inferior nasal vein / artery
  • superior temporal vein/ artery
  • inferior temporal vein / artery
40
Q

what are the retinal vessels features ?

A

•Arteries versus veins
• Central retinal artery
usually nasal to vein

• Arteries smaller diameter

• Colour
• Arteries light red = more oxygen
• Veins dark red
. both become narrower as they move further away from optic nerve head

• Cross-over
• Arteries and veins have crossing
points

41
Q

what is A/V ratio ?

A
  • the width of artery compared to the vein
  • vein have wider diameter compared to artery
  • can be expresses as a fraction
    . 3/4
    . 2/3
    . 1/2

. must be measured in the same region for artery and vein

42
Q

why is is important to assess A/V ration of blood vessels ?

A
  • can be an indication of a person’s general health
  • can signify cardiovascular conditions
  • atherosclerosis can affect apparent blood vessel width
43
Q

how should blood vessels width be ?

A
  • uniform calibre ( width ) of vessels

- should be similar before , during and after crossing

44
Q

how does fundus appearance change from patient to patient ?

A

. more skin pigment = darker fundus appearance

45
Q

what is tesselated fundus ?

A

• Elongation of the globe
along along with hypoplasia of the retinal pigment epithelium may expose the underlying choroidal vessels giving rise to a tesselated fundus appearance

cs (18 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions