Glaucoma

Question 1

What is aqueous humour?

Answer 1

fluid produced by the ciliary body
- provides nutrition and maintains pressure in the eye

contained in the anterior chamber
typically exits via the trabecular meshwork and schlemm canal
- blockage of this network raises the intraocular pressure

Question 2

What is normal intraocular pressure? What is raised intraocular pressure? What does it depend on?

Answer 2

normal intraocular pressure
10-21 mmHg

raised intraocular pressure
> 21 mmHg
- depends on aqueous humour production and outflow

Question 3

What are the types of glaucoma?

Answer 3

congenital and developmental glaucoma
- primary congenital glaucoma
- developmental glaucoma

primary adult glaucoma
- primary open angle glaucoma
= develops over time, no signs or symptoms
= most common
- primary angle closure glaucoma
= develops suddenly
= medical emergency, more likely to cause blindness
- primary mixed mechanism glaucoma

secondary glaucoma

Question 4

What are the risk factors for POAG?
primary open angle glaucoma

Answer 4

age - >40 years old
family history
diabetes
myopia (short sightedness)

Question 5

What are the symptoms of POAG?
primary open angle glaucoma
How is it identified?

Answer 5

asymptomatic until late stages
- field loss already occurred

acute POAG
- halos while looking in light
- redness in the eye
- cloudiness in the eye
- blurred vision
- pain
- nausea and vomiting

diagnosed via screening

Question 6

What are the signs of POAG?

Answer 6

raised intraocular pressure
optic nerve head damage
loss of visual field

Question 7

What are the forms of drug administration for glaucoma? What are the advantages and disadvantages?

Answer 7

eye drops
- can be difficult to administer for elderly, visually impaired and arthritic
- short contact period so less effective
- systemic side effects

eye ointments
- longer contact period as they are more viscous so more effective
- no systemic side effects

eye injections

implants/inserts
hyperosmotic agents
punctal plugs

Question 8

What are the different treatments for glaucoma? How do they work?

Answer 8

INCREASE aqueous humour outflow
- prostaglandins, prostamides and miotics

DECREASE aqueous humour formation
- beta blockers, carbonic anhydrase inhibitors (oral and topical)

BOTH
- alpha adrenergic agonists

Question 9

How do beta blockers work? What are the types?
What are the disadvantages?
When are they contraindicated?
When should they not be used?

Answer 9

decrease aqueous humour formation
- betaxolol, carteolol, levobunolol, timolol

disadvantages
- systemic absorption may occur

contraindicated in
- bradycardia, heart block, uncontrolled heart failure, uncontrolled asthma

cannot be used in
- diabetes, asthma and COPD

Question 10

What are the local side effects associated with beta blockers?

Answer 10

ocular stinging
burning
pain
itching
erythema

Question 11

How do prostaglandins work? What are the types? When is it contraindicated? When should use be cautioned?

Answer 11

increase aqueous humour outflow
- latanoprost, tafluprost, travoprost, bimatoprost

contraindicated
- patients with history or herpes eye infections
- aphakia, pseudophakia
- torn lens capsule
- anterior chamber lenses

caution
- macular oedema
- iritis
- uveitis

Question 12

What are the local side effects associated with prostaglandins? What are the systemic side effects associated with prostaglandins?

Answer 12

local
- brown pigmentation, blepharitis, ocular irritation and pain
- conjunctival hyperaemia, rash, dry eyes, headaches
- photophobia, darkening/thickening/lengthening of eye lashes

systemic
- dyspnoea, exacerbation of asthma, dizziness, arthralgia
- chest pain, palpitations, exacerbation of angina

Question 13

How do carbonic anhydrase inhibitors work? What are the types? What are the side effects associated?

Answer 13

decreases aqueous humour formation
- acetazolamide, brinzolomide, dorzolamide

side effects
- blood disorders, rashes
- electrolyte disturbances, metabolic acidosis

Question 14

How do sympathomimetics work? What are types? What are the cautions for it?

Answer 14

decreasing aqueous humour production and increasing aqueous humour outflow
- brimonidine, apraclonidine
= selective alpha adrenoceptor agonist

caution
- severe CV disease, cerebral or coronary insufficiency, Raynaud’s disease

Question 15

How do miotics work? What are the types?

Answer 15

act by opening inefficient drainage channels in the trabecular network
- pilocarpine

are used for angle closure glaucoma

Question 16

What is the issue with wearing contact lenses while using eye treatments?

Answer 16

some drugs and preservatives can accumulate in hydrogel lenses (soft)

lenses should be removed before instillation and not worn during period of treatment

hard (rigid) lenses can be worn