3 - Opth - Glaucoma - Primary Open Angle Glaucoma

Question 1

after glaucoma this is?

Answer 1

commonest cause of site loss

Question 2

Initial vision disruption?

Answer 2

peripheral visual field loss

Question 3

when do symptoms occur and why?

Answer 3

asymptomatic until almost blind as macula is unaffected

- can have 90% loss of fibres before Sx

Question 4

Risk factors for POAG - 6

Answer 4

Afro caribbean
myopia
DM
steroids
Raised IOP
FHx

Question 5

Pathogenesis of POAG - 6 steps

Answer 5

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

Question 6

Main features of POAG

Answer 6

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

Question 7

Glaucomatous optic disc changes in POAG

Answer 7

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

Question 8

Visual field defects from POAG

Answer 8

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

Question 9

Medical treatment aim

Answer 9

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

Question 10

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

Answer 10

reduce by 30%

one eye only - compare at 3-6 weeks

Question 11

Five types of drugs used for POAG

Answer 11

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

Question 12

2 surgical treatments of POAG + explanation

Answer 12

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

Question 13

Prostaglandin analogues - route, mechanism, SEs

Answer 13

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

Question 14

Beta blockers - route, mechanism, SEs

Answer 14

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

Question 15

A-agonists - route mech SEs

Answer 15

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

Question 16

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

Answer 16

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

Question 17

Systemic carbonic anhydrase inhibitors - route, caution in, SE

Answer 17

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

Question 18

Miotics - main one, mech, CI’s, SE

Answer 18

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

Question 19

1st line
2nd line
3rd line

Answer 19

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