3 - Opth - Glaucoma - Primary Open Angle Glaucoma Flashcards Preview

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Flashcards in 3 - Opth - Glaucoma - Primary Open Angle Glaucoma Deck (19):
1

after glaucoma this is?

commonest cause of site loss

2

Initial vision disruption?

peripheral visual field loss

3

when do symptoms occur and why?

asymptomatic until almost blind as macula is unaffected
- can have 90% loss of fibres before Sx

4

Risk factors for POAG - 6

Afro caribbean
myopia
DM
steroids
Raised IOP
FHx

5

Pathogenesis of POAG - 6 steps

- raised IOP +/or vascular factors (DM)
- ischaemic loss of retinal nerve fibres
- optic disc excavation (cupping)
- visual field defects
- tunnel vision
- blindness

6

Main features of POAG

Glaucomatous optic disc changes
visual field defects
open angle
IOP >21 (although not part of definition)
generally bilateral but not always symmetry

7

Glaucomatous optic disc changes in POAG

CtoD ratio >0.5 --> suspect glaucoma
ratio >0.7 almost certainly pathology
disc pales as disease progresses - optic atrophy

8

Visual field defects from POAG

arcuate Scotoma - areas of lost vision - n-shaped - may spread and coalesce - nasal and temp fields lost first - eventual tunnel vision and blindness
Common presentation: arcuate scotoma and nasal step

9

Medical treatment aim

to decrease IOP - prevents further field loss but doesnt reverse damage

10

Drug treatment of POAG - reduce IOP how much? process?

reduce by 30%
one eye only - compare at 3-6 weeks

11

Five types of drugs used for POAG

Prostaglandin (analogues)
BBs
A-adrenergic agonists
Carbonic anhydrase inhibitors
Miotics

12

2 surgical treatments of POAG + explanation

Argon laser Trabeculoplasty - improves drainage (uncommon in UK)
Surgical Trabeculectomy - valve at limbus allows aq drainage to conjunctival bleb - prevent bleb healing with 5FU drops

13

Prostaglandin analogues - route, mechanism, SEs

drops - latanoprost
increase uveoscleral aq outflow
SE - red eyes, iris colour change, eyelash growth,

14

Beta blockers - route, mechanism, SEs

drops - timolol
decrease aq prod
SE- dry eyes, corneal anaesthesia, bradycardia (can be fatal in heart block), bronchospasm (CI asthma), depression

15

A-agonists - route mech SEs

drops - apraclonidine
decrease aq prod + increase aq outflow
SE - mydriasis (dilation) lethargy, dry mouth, hypotension, w/ MAOIs theres risk of HTN crisis

16

Carbonic anhydrase inhibitors (non-systemic) route mech and SEs

drops - dorzolamide
dec aq prod
SE pain on application, local allergic reaction

17

Systemic carbonic anhydrase inhibitors - route, caution in, SE

PO/IV
acetazolamide
caution in pregnancy and renal stone history
Se met acidosis, hypokalaemia, paraesthesia, GI upset

18

Miotics - main one, mech, CI's, SE

pilocarpine
contrcits pupil, unblocking trab meshwork, improved drainage
CI - anterior uveitis, high myopia, retinal detachment, aphakia
SE - dec acuity, brow ache

19

1st line
2nd line
3rd line

1 - BB/prostaglandin
2 - switch above, combine above, add/switch to - miotic/CA-/adrenergic agonist
3 - laser/surgery

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