3 - Opth - Glaucoma - Physiology + Assessment/screening Flashcards
1
Q
3 ways aqueous is “produced” by ciliary body..
A
active secretion 70%
ultrafiltration 20%
osmosis 10%
2
Q
Where does aqueous flow
A
enters posterior chamber and flows into anterior chamber
3
Q
Route of aqueous drainage
A
drains at angle via trabecular meshwork > chlemms canal > collecting channels > venous system
4
Q
Intra-ocular pressure
- general range?
- daily variation?
- determined by?
A
- 10-21mmHG
- can vary by around 5 mmhg daily - higher at night (dilatation) and in morning
- determined by - rate of aq prod + resistance to aq drainage
5
Q
Three screening/assessments of glaucoma
A
visual field test
optic disc visualisation
IOP testing
6
Q
What is the ISNT rule
A
in a normal disc, size of ..
inferior > superior > nasal > temporal
7
Q
What is optic disc visualisation is suggestive of glaucoma?
A
- increase of cup size (atrophy of nerve fibres on disc rim)
- asymmetrical cupping
- notching of the rim
- haemorrhage
- vertical cup elongation
- vessels may be nasally displaced, bayonetted (appear from nowhere/disappear into disc)
8
Q
IOP testing - what used? how does it work?
A
Goldmann tonometer
exerts pressure on cornea and gives IOP estimation
