Glaucoma Flashcards
What is glaucoma?
Progressive optic neuropathy
elevated intraocular pressure elevated IOP damages the normal visual process
What are the main factors that influence the level of IOP in the eye?
the rate of aqueous humour production
the resistance of the drainage of the aqueous humour
Which investigations are performed in glaucoma?
cup disc ratio
IOP measurement
visual field analysis
visual acuity
What disability is associated with glaucoma?
significant peripheral field loss may result in patient unable to legally drive
advanced glaucoma results in permanent blindness
How is glaucoma classified?
1 - open angle glaucoma
2 - angle closure glaucoma
How is primary open angle glaucoma classified?
POAG
1 - elevated IOP of >21mmHg
2 - open angle
3 - glaucomatous cupping and visual field loss
Describe primary open angle glaucoma
chronic, slowly progressive and usually bilateral disease
What causes the rise in IOP in POAG?
increased resistance of the drainage channels in the angles of eye such as the trabecular meshwork
How does POAG present?
usually asymptomatic due to its incidious onset, until is causes significant visual field loss
How is POAG managed/treated?
involves reducing IOP, monitoring visual fields and visual acuity
Treatment options
1 - medical therapy
2 - argon laser trabeculoplasty
3 - surgical - trabeculectomy
What is the medical therapy used for POAG?
List the topical drugs used
aim is to achieve reduction of IOP to prevent further optic nerve damage
topical drug treatment is initiated:
- beta blockers
- prostaglandin agonist
- alpha adrenergic agonist
- topical carbonic anhydrase inhibitors
- miotics
- systemic carbonic anhydrase inhibitors
What is primary angle-closure glaucoma?Unilateral/bilateral?
a condition whereby the obstruction to the aqueous outflow (drainage) is due to the closure of the angle by the peripheral iris frequently BILATERAL predominant in females
How does PAOG progress?
raised IOP +/- vascular factors –> loss of retinal nerve fibres –> optic disc excavation (cupping) –> visual field defects –> tunnel vision –> blindness
How is POAG detected?
asymptomatic until almost blind screening early to detect cases optic disc examination intraocular pressure readings visual field analysis
Which method is used to assess visual fields?
Humphrey - gold standard
What are the complications of beta blockers?
cardiac & respiratory effects
What are the complications of alpha agonists?
dizziness
syncopy
allergy
What are the complications of prostaglandin analogues?
lash growth
pigmentation
What are the complications of cholinergic?
eye ache
dim vision
What are the complications of carbonic anhydrase inhibitors?
taste problems
acidosis
What are the new advances in topical medications?
longer acting agents
combination agents
preservative free drops
What are the symptoms of acute angle closure glaucoma?
pain
blurred vision
vomiting
What are the signs of acute angle closure glaucoma?
corneal oedema
red eye
fixed mid-dilated pupil
What are the risk factors for angle closure glaucoma?
shallow anterior chamber
hypermetropia
FH
How is acute closure glaucoma treated?
EMERGENCY SITUATION
- aim to reduce IOP
- intensive miotic therapy e.g. pilocarpine eye drops every 5 mins
- drugs that reduce the aqueous secretion e.g. IV or oral acetazolamide
- analgesics and antiemetics good for pain and N&V
What permanent treatment is used after the acute phase in closed angle glaucoma?
peripheral laser iridotomy is performed in both eyes
trabeculectomy surgery may be required in resistant cases
What are the secondary causes known to interfere with aqueous humour dynamics?
- Inflammation e.g. uveitis
- Neovascular e.g. secondary to diabetic retinopathy, CRVO
- Pigment dispersion syndrome
- Pseudoexfoliation syndrome
- Traumatic hyphaema
What is rubeotic glaucoma?
new vessels occlude angle causes - CRVO or diabetic retinopathy
