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Year 4 > Glaucoma > Flashcards

Glaucoma Flashcards

1
Q

what is glaucoma?

A

group of diseases characterised by progressive optic nerve damage and visual field loss
raised IOP

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2
Q

pathogenesis of glaucoma?

A

usually due to blockage of aqueous outflow leading to raised IOP which causes damage and loss of retinal fibres at optic disc resulting in visual field loss

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3
Q

which visual fields are lost first in glaucoma?

A

peripheral
periphery has several photoreceptors connecting to 1 ganglion cell whereas 1 photoreceptor connect to several ganglion cells at macula
therefore damage to 1 ganglion cell at periphery causes lots of photoreceptors to be lost

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4
Q

signs of glaucoma?

A

peripheral field loss
raised IOP
optic disc cupping

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5
Q

how can glaucoma be tested for?

A

tonometry (tests IOP)
visual field testing
clinical examination to look at optic nerve

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6
Q

how is normal IOP defined?

A

normal range = within 2 standard deviations above and below the mean IOP
(16-21mmHg)

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7
Q

how is applanation tonometry done?

A

instrument used to press down on eyeball to measure pressure inside
like pressing on a football to test the air pressure inside

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8
Q

how are visual fields assessed?

A

goldman fields or other modern methods

both show arcuate defect (arc of visual field loss around centre)

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9
Q

why can glaucoma be last to present?

A

gradual loss of visual field so the brain fills in the gaps and you dont really notice it

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10
Q

what is cupping and why does it happen in glaucoma?

A

where the cup in the middle of the optic disc becomes larger in relation to the disc as a whole
due to nerve fibres in the optic nerve dying off so the cup expands to fill the space

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11
Q

what else can be seen at the optic disc in glaucoma?

A

haemorrhages

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12
Q

types of glaucoma

A 
open angle (primary or secondary)
closed angle (primary or secondary)
most are open angle
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13
Q

what can cause secondary closed angle glaucoma?

A

diabetes where new poor quality vessels form and ischaemia occurs, central retinal vein occlusion can also cause

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14
Q

what can cause secondary open angle glaucoma?

A

cells in the eye (WCCs in uveitis or RBCs from trauma or haemorrhage) can increase pressure, occlude vessels and block drainage angle

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15
Q

what causes primary open angle?

A

unknown
raised IOP due mainly to blocked drainage of aqueous somehow
may be vascular
(2nd most common cause of blindness in UK)

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16
Q

risk factors for primary open angle?

A

age
raised IOP
afro-carribean origin
family history

17
Q

aim of treatment in primary open angle?

A

need to lower IOP to point where it wont cause further damage within patient’s lifetime (so lower pressure needed in younger people)

18
Q

what drugs can be used in glaucoma?

A 
beta blockers
CA inhibitors
prostaglandins/prostaglandin analogues 
parasympathomimetics
sympathomimetics
19
Q

what do prostaglandins/analogues do?

A

block outflow through the iris by making iris vessels more leaky
increase uveoscleral outflow

20
Q

side effects of prostaglandins?

A

well tolerated

can make iris darker and increase lash growth but patients usually dont care

21
Q

what do beta blockers do?

A

reduce aqueous secretion (turn off the tap)

22
Q

side effects of beta blockers?

A

cant use in asthma
can cause bradycardia, heart block etc
effects can decrease with time as beta receptors are upregulated

23
Q

what do carbonic anhydrase (CA) inhibitors do?

A

reduce aqueous secretion (turn off tap)

24
Q

side effects of CA inhibitors?

A

no systemic effects

acidic so stings when going in and can cause local irritation

25
Q

what do parasympathomimetics do?

A

increase outflow by opening trabecular meshwork

26
Q

side effects of parasympathomimetics?

A 
few systemic effects
pupil constriction (cant dilate in dark so can struggle to see in dark)
pain
dimming of vision at night
more often used in closed angle
27
Q

what do sympathomimetics do?

A

increase outflow

dilate pupil

28
Q

side effects of sympathomimetics?

A

local irritation
hyperaemia
cardio side effects
long term use reduces success of surgery

29
Q

usual order of treatment in glaucoma?

A

prostaglandin > beta blocker > CA inhibitor > surgery

usually start thinking about surgery once theyre taing 2 meds

30
Q

what surgery can be used for glaucoma?

A

trabeculectomy

makes a guarded fistula into the anterior chamber

31
Q

risks of trabeculectomy?

A

infection risk

increases risk of cataract

32
Q

causes of 2ndary open angle glaucoma?

A

blood
uveitis
protein in lens
pseudo-exfoliation

33
Q

long or short sighted increases risk of acute angle closure glaucoma?

A

long sighted (hypermetropes)

34
Q

management of acute angle closure glaucoma?

A

reduce IOP medically with IV acetazolomide

peripheral iridotomy

Year 4 (83 decks)

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