Wk 16: Glaucoma Flashcards
What is glaucoma?
Progressive damage to nerve leads to impaired vision + blindness
What are the characteristics of glaucoma?
- Visual field defects
- Changes to the optic nerve head
- Nerve fibre layer defects
What is ocular hypertension?
Consistently/recurrently elevated intraocular pressure + no sign of glaucoma
What is intraocular pressure?
- Keeys eye in shape of globe
- Maintained by balance btw prod + outflow of aqueous humour
- Normally: 10-21 mmHg
What is the intraocular pressure in acute angle closure glaucoma?
70 mmHg
What is angle closure glaucoma?
Angle btw iris + cornea partially closed:
- Blocks trabecular meshwork + prevents drainage of intraocular fluid
- As fluid prod, pressure inc + optic nerve damaged
- Chronic/acute
What is open angle glaucoma?
Angle btw iris + cornea open:
- Chronic
- IOP can be inc or w/in range
- Both eyes affected
- W/o treatment: asymptomatic, visual field defect when loss of optic nerve fibre
- Treatment: visual field defects
When would you suspect acute ACG?
- Acute painful red eye
- Female
- Asian
- Long sighted
- Older
What are the symptoms of acute ACG?
- Blurred vision
- Headache
- Adrenergic drugs or antimuscarinic
- Semi-dilated + fixed pupil
- Tender hard eye
What is the management of acute ACG in emergency situations?
- 1 drop pilocarpine 2% blue eyes OR
- 1 drop pilocarpine 4% brown eyes
- AND single dose oral acetazolamide 500mg
What is the management of acute ACG in secondary care?
- Topical + IV drugs red intraocular pressure + analgesia
- Surgery: aqueous humour flow from posterior chamber into anterior
What are the risk factors of chronic OAG?
- Raised intraocular pressure
- Age
- Fx: first degree
- Black african
- Corticosteroid: inc outflow of aqueous humour
- Short sighted
- Diabetes
What are the typical features of chronic OAG?
- Inc IOP
- Visual field defects
- Cupped optic disc
What is the treatment for ocular hypertension in chronic OAG?
- Topical prostaglandin w/ 24 mmHg or risk of visual impairment
- Not tolerated: another topical prostaglandin or bblocker
What is the treatment for advanced COAG?
- Surgery w/ augmentation (chemo)
- Topical prostaglandins + other topical IOP lowering agents
- Laser (trabeculectomy)
What is the MOA of topical prostaglandins?
Lower IOP by inc uveoscleral outflow, inc outflow of aqueous humour
What are examples of topical prostaglandins?
OD:
- Latanoprost
- Travoprost
- Bimatoprost
What are the adverse effects of topical prostaglandins?
Local:
- Inc brown pigmentation
- Darkening, thickening + lengthening of lashes
- Blepharitis
- Ocular pain + irritation
Systemic:
- Dyspnoea, asthma
- Dizzy, headache
What is the MOA of topical beta blockers + examples
Lower IOP by red aqueous prod:
- Betaxolol
- Carteolol
- Timolol
- OD/BD
What are the adverse effects of topical b-blockers?
- Local: stinging, burning, itching
- Systemic: bradycardia, sleep disturbance, hallucination
What is the MOA of topical sympathomimetics and give an example?
Red IOP by dec aqueous prod + inc aqueous drainage
- Brimonidine tartrate 0/2%
- One drop BD, 12 hrs apart
What are the adverse effects of topical sympathomimetics?
- Local: stinging, dry mouth + abnormal taste in mouth
- Interaction: alcohol, barbiturates, opiates, sedatives + anaesthetics
What is the MOA of carbonic anhydrase inhibitors and give an example?
Red IOP by red secretion of aqueous humour:
- Topical: Brinzolamide/Dorzolamide BD/TDS
- Oral: Acetazolamide 0.25g-1g daily
What are the adverse effects of carbonic anhydrase inhibitors?
- Local: blepharitis/eye irritation, pain, dryness
- Systemic: non in topical
What are the interactions of carbonic anhydrase inhibitors?
- Aspirin: acetazolamide = metabolic acidosis
- Anticonvulsant: acetazolamide modifies metabolism
- Ciclosporin: rapid inc in serum cyclosporine levels + renal toxicity
What is the MOA of topical miotics + give an example?
- Inc flow of aqueous humour from eye
- Pilocarpine: 1 drop QDS
- Pilogel: 1 drop nocte
What are the local adverse effects of topical miotics?
- Burning, itching
- Brow ache
- Conjunctival vascular congestion
- Vitreous haemorrhage
- Retinal detachment
What are the patient counselling points for COAG?
- Wash hands
- Remove contact lense before applying
- Shake before each use
- 5 mins btw each prep: drops, gels then ointment
- Minimise systemic abs: close eyes after administering, press tear duct against nose for 1 min
- Replace after 4 wks
- If visual field affects both eyes inform DVLA
- If itchy eyes, inform doctor
Which eye drop requires refrigerator storage before opening?
Latanoprost, once opened keep in cool place for 4 wks
