Opthalmology

Question 1

acute angle closure glaucoma

• due to?
• predis factors?
• features

Answer 1

Acute angle closure glaucoma = rise in IOP due to impaired aqueous outflow

Predis factors

- Long sightedness (hypermetropia)
- Pupillary dilatation
- Lens growth ass w age 

Features
	- severe pain: ocular or headache
	- decreased visual acuity
	- syms worse with mydriasis (e.g. watching TV in a dark room)
	- hard, red-eye
	- haloes around lights
	- semi-dilated non-reacting pupil
	- corneal oedema >> dull or hazy cornea
Systemic fts: N&V, abdo pain

Question 2

acute angle closure glaucoma tx options

Answer 2

Emergency: urgent opth referral
Emergency medical tx to lower IOP
- combination of eye drops, EG:
○ a direct parasympathomimetic (e.g. pilocarpine: contraction of the ciliary muscle → opening the trabecular meshwork → increased outflow of the aqueous humour)
○ b-blocker (e.g. timolol, decreases aqueous humour production)
○ a-2 agonist (e.g. apraclonidine, dual mechanism, decreasing aqueous humour production and increasing uveoscleral outflow)
- IV acetazolamide: reduces aqueous secretions
Once acute attack settles, definitive mx
Laser peripheral iridotomy (makes hole in peripheral iris > aqueous humour flowing to the angle)

Question 3

pilocarpine

• what is it
• action

Answer 3

a direct parasympathomimetic (e.g. pilocarpine: contraction of the ciliary muscle → opening the trabecular meshwork → increased outflow of the aqueous humour)

Question 4

timolol

• what is it
• action

Answer 4

b-blocker (e.g. timolol, decreases aqueous humour production)

Question 5

apraclonidine

• what is it
• action

Answer 5

a-2 agonist (e.g. apraclonidine, dual mechanism, decreasing aqueous humour

Question 6

action of IV acetazolamide in acute angle closure glaucoma

Answer 6

reduces aqueous secretions

Question 7

triggers for acute angle closure glaucoma

• type of eyedrop
• 2 medications

Answer 7

Trigger = mydriatric drops

Other trigger drugs: anticholinergics, TCAs (eg amitriptyline)

Question 8

primary open angle glaucoma 
- 1st line mx?
- other options
& mechs of action of all of them
- if have asthma avoid what

Answer 8

Mx:
1. Prostaglandin analogue eye drop (EG latanoprost)
2. B-blocker (timolol, betaxolol
a. or carbonic anhydrase inh (dorzolamide)
b. or sympathomimetic eyedrop (EG brimonidine)
c. Miotic: pilocarpine
More adv: surgery or laser

mech of action
• Prostaglandin analogue: increases uveoscleral outflow
• B-blockers: reduce aqueous production
• Carbonic anhydrase inh: reduces aq production
• Sympathomimetic eyedrop: reduces aq production + increases outflow
• Pilocarpine = muscarinic rec agonist = increases uveoscleral outflow

Question 9

RF for primary open angle glaucoma

Answer 9

• Increasing age
	• Genetics (1st degree rels 16% chance)
	• Afro-caribbean
	• Myopia 
	• HTN
	• DM
Steroids

Question 10

primary open angle glaucoma

• latanoprost
• pilocarpine
• brimonidine
• timolol

what are they; how do they work

Answer 10

• B-blockers work by reducing aqueous production (timolol, betaxolol, levobunolol)
  
  • Latanoprost = prostaglandin analogue = increases uveoscleral outflow
  • Pilocarpine = muscarinic agonist (miotic) = pupil constriction > increase uveoscleral outflow.
  • Brimonidine = sympathomimetic (a2 adrenoceptor agonist) = dual action (reduce aqueous production and increase outflow)