Normal fundus 2 Flashcards
When do nerve fibres get myelinated?
Level of lamina cribrosa
Where do nerve fibres sometimes retain their myelin?
On the disc or the retina
What are myelinated nerve fibres?
Non progressive
non pathogenic condition
What are the two layers of capillaries of the fundus?
A superficial network in nerve fibre layer
A deep network at junction of INL and the OPL
What do you find in the central macula?
No capillaries
What is the outer layer of the retina supplied with?
By underlying choroidal circulation
What do the Blood vessels walls look like
Transparent
How is the light reflex formed by>?
Reflection at convex cylinder blood column
Reflection from the convex vessel walls
Both surfaces act as convex mirrors
What is the purpose of retinal vessels?
Supply oxygen and other nutrients from the blood to first six layers of the retina
What can you detect by assessing the blood vessels of retina?
Systemic diseases such as hypertension, diabetes, arteriosclerosis
What is the general rule for A/V and V/A crossing?
Arterioles dont cross arterioles
Venules dont cross venules
Where does the artery remain?
Arteriole remains at normal level of the nerve fibre layer and the venule dips to avoid the arteriole
What happens to A/V crossing in hypertension?
A/V crossing changes as venule is compresses by sclerosed arteriole may cause deflection of venule
What is the name for changes in course of the vessels?
Tortuosity
What are tortuosity of arterioles?
May be congenital - should be uniform across the fundus
isolated regions of arteriole tortuosity suggests sclerosis
What can pathology show?
Narrowing of arteries
increase in width of vein
What do arteries do ?
Arteries get narrower
What do veins do?
Veins get wider
What is the normal A/V ratio?
2/3
When do you find generalised narrowing of the arteries?
Healthy elderly px
How is severe narrowing of arteries caused?
Systemic hypertension
What does focal narrowing indicate?
Hypertension
what other signs can you see ?
Leakage of blood vessels
What does leakage of blood vessels show?
Haemorrhages (blood)
hard Exudates (lipids)
oedema (fluid)
