Flashcards in Glaucoma Deck (19):
What is glaucoma?
-what is a risk factor?
A group of diseases characterised by progressive optic nerve damage and visual field loss.
Raised intra-ocular pressure is a prominent risk factor
What is the pathogenesis of glaucoma?
-Usually blockage to aqueous outflow
-Raised intra-ocular pressure
-Damage and loss of retinal nerve fibres at optic disc
-Visual field loss
What are the signs of glaucoma?
Raised intra-ocular pressure
characteristic field defects
Optic disc cupping
What is included in the diagnosis and management of glaucoma?
Fields - perimetry
optic nerve/disc - clinical examination
What changes to the optic disc is seen in glaucoma?
-fewer nerves course through optic disc
-Cup: disk ratio > 0.4-0.7
-vertical thinning and notching of neural rim
(Neural rim= space between inner cup and surrounding disc, and normal rims follow ISNT rule)
Haemorrhage at disc
Disc vessels displaced nasally
Optic atrophy – optic disc becomes pale as damage progresses
What is the ISNT rule for optic discs
Inferior rim Thickest
Temporal rim Thinnest
In glaucoma this is lost
What is the classic visual field loss in glaucoma?
-Central vision typically SPARED e.g. late stage patients may have 20/20 central vision but peripheral blindness
For primary open angle glaucoma:
-how does this present?
No symptoms till late
a disease of signs
needs to be screened for
Most detected by optometrist at routine examination
What are the risk factors for primary open angle glaucoma?
raised intraocular pressure
What is the aim of treatment for primary open angle glaucoma?
Lower IOP to a level that prevents further nerve damage
Target IOP varies between patients
What is the first line medical treatment for primary open angle glaucoma?
Prostaglandin analogues (Bimatoprost 300micrograms/mL, every evening)
-increase uveoscleral outflow
-make iris vessels more leaky
Beta blockers (Timoptol, laevobutanol)
-Reduce aqueous secretion
Systemic side effects -reduced by shutting eyes for a few minutes
-Few topical side effects
Carbonic anhydrase inhibitors and systemic drugs (Acetazolamide PO or IV, 0.25-1g daily)
-Very effective at lowering IOP
-BUT systemic side effects – Parasthesia, peri-oral tingling, renal calculi
-Short term use only
-can use topical but local irritation and much less effective (no systemic side effects)
Sympathomimetics (adrenaline, propine, alphagan)
local irritation, hyperaemia
cardiovascular side effects
long term use reduces the success of surgery
Parasympathomimetics/ Miotics (Pilocarpine Hydrochloride 0.5%, topical eye drops, up to four applications daily, adrenaline, propine, alphagan)
few systemic side effects
Many local side effects
pupil constriction - pain, dimming of vision, problems at night
What is the usual order of treatment for primary open angle glaucoma
What surgery is used for primary open angle glaucoma?
What are the pros and cons of surgery?
Surgery more effective
But intra-ocular surgery
Increases progression of cataract
What can cause secondary open angle glaucoma?
Acute closed angle glaucoma:
-what is this?
-who usually suffers this?
Closure of the angle by iris causes sudden rise in IOP
Disease of symptoms
What are the symptoms of acute angle closure glaucoma?
Nausea + vomiting
Fixed mid-dilated pupil
What is the treatment for acute angle closure glaucoma?
Reduce IOP medically
Peripheral iridotomy – surgical or laser
Beta blockers (Timolol 0.5% single dose)
Steroids (Prednisolone 1% one dose every 15 minutes for an hour, followed by hourly doses)
Apraclonidine 0.5-1% single dose
Natural lens: Pilocarpine 1-2% single drop an hour after treatment commenced
No natural lens: Phenylephrine 2.5% single drop
Acetazolamide given IV (500mg over 10 minutes), with further 250mg slow-release tablet after an hour
If no response, systemic hyperosmotics used (glycerol PO 1 gm/kg of 50% solution in lemon juice or mannitol 20% solution IV 1-1.5 gm/kg)