Normal Fundus Flashcards
What is the definition of the fundus?
The interior of the globe as sen with the ophthalmoscope
Where does the fundus extend?
All the way out to the ora serrata
What is the ora serrata?
Where the retina joins the ciliary body to the equator of the eye
With which technique can you see the ora serrata?
Direct ophthalmoscope
How does the fundus background appear?
Orange/red background
Why does the fundus look orange/ red?
Light directly reflected from choroidal blood vessels
light reflected from sclera and transmitted through choroidal blood vessels
What layers does the light pass through in the retina?
RPE/Bruchs membrane/Bruchs membrane then back from sclera to choroid 2nd time
What depends on amount of light directly reflecting from choroidal blood vessels and transmitting through choroidal blood vessels?
Degree of pigmentation on retina
Degree of pigmentation of choroid
What layers contribute to Fundus appearance ?
All retina layers?
What are the full retina appearances?
RPE/Photoreceptors/ External limiting membrane/ONL/OPL/INL/IPL/Ganglion cells/nerve fibre layer/internal limiting membrane
What types of fundus do you get ?
Uniform stippled
Tesselated (Tigroid)
Albinotic
What appearances do you get with uniform stippled fundus?
- Stipple= paint with individual dots
- Dark or negroid
- Medium or caucasian
- light or blond
What are dark negroid fundus?
Heavily pigmented RPE
heavily pigmented Choroid
What are light or blond fundus?
Lightly pigmented RPE
Lightly pigmented choroid
What is a tigroid fundus?
Lightly pigmented RPE and normal to heavy pigmented choroid
What is an Albinotic fundus?
Virtually no pigment in RPE or choroid
Why are some fundi more pigmented than others?
Depends on :
- Age
- Race
- Hereditary
- Metabolic
Do the retina and choroid pigmentation always run parallel?
No
Define the OPTIC DISC?
The ophthalmoscopic view of the optic nerve head
What are the features of OPtic disc?
Size Shape Colour margins level vessels surroundings
What does the colour of optic disc depend on?
The white lamina cribrosa and myelinated nerve fibre behind the lamina
The red blood in capillaries supplying the disc
What are the margins in optic disc?
- -Sharp clear image of margins, especially on nasal side which can indicate optic atrophy
- –Very blurred margins on temporal side can indicate oedema
- –Distributions of nerve fible layer on healthy disc leads to relative blurring of margins on nasal 2/3rds of disc
What does blurring of nasal side of optic disc indicate?
Optic atrophy
What does blurring of temporal side of optic disc show?
Oedema of disc
What levels of optic disc do you get?
Cupping and cup depth
What is cupping in optic disc normal?
15% cant detect cup
- Can be measured using Vertical CD ratio
- > 0.6 suspicious to glaucoma
- > 0.1 difference between eyes suspicious
?What size of cup suggests glaucoma ?
> 0.6
What is parallax?
When moving ophthalmoscope beam, areas at different levels move at different speeds
What vessels are there in optic disc?
CRA- coronary retinal artery
CRA- coronary retinal vein
Cilio retinal arteries
What is features of CRA?
Has all the characteristics of a true artery but after branching soon becomes a arteriole
What is features of CRV?
Has all the characteristics of true vein but after branching soon becomes a venule
What is the pressure of CRV?
Constant about 2mmHg than mean IOP
What happens when IOP greater than CRV pressure?
Partial collapse of the vein, not recover until IOP falls back below of that of CRV
What is the features of Cilio retina arteries?
Not branches of CRA but derived from blood vessels supplying the choroid
What are the surroundings of optic disc?
Some layers stop short of the disc and cause
- Scleral ring where RPE and choroid stop short of disc
- Choroidal crescent where RPE stops short of disc
- Pigment stops- build up of lot of pigment at edge of disc
