Glaucoma Flashcards

1
Q

what is glaucoma?

A

Progressive optic neuropathy
Characterised by optic nerve head (disc) changes and corresponding visual field loss

Raised intraocular pressure

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2
Q

how does glaucoma occur?

A

poor aqueous production + drainage:
 Anterior chamber angle – angle between cornea + iris, contains trabecular meshwork
 Ciliary body – produces aqueous => post chamber (behind iris) => through pupil => anterior chamber

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3
Q

how does aqueous humor outflow?

A
  1. uveoscleral 25%
  2. trabecular 75%
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4
Q

where does trabecular aq. humor outflow?

A

drains into the episcleral circulation

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5
Q

where does uveoscleral aq. humor outflow?

A

drains into the choroidal circulation

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6
Q

describe the intraocular pressure (IOP)

A

balance between inflow and outflow of aqueous humor

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7
Q

what is the ideal IOP?

A

11-21 mmHg

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8
Q

what IOP indicated high risk glaucoma?

A

21 mmHg

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9
Q

what can cause IOP fluctuations

A
  1. time of day
  2. heartbeat
  3. blood pressure
  4. respiration
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10
Q

what are the different types of glaucoma?

A
  1. primary open angle glaucoma
  2. primary angle closure glaucoma
  3. secondary open angle glaucoma
  4. secondary angle closure glaucoma
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11
Q

describe primary open angle glaucoma

A

most common

abnormal resistance of aqueous outflow causing high pressure induced ischemia of optic nerve reducing axoplasmic flow

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12
Q

primary open angle glaucoma risk factors

A

smoking
diabetes
hypertension
high cholesterol
short-sighted

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13
Q

mechanism of action of primary open angle glaucoma

A

acute/chronic
sudden raise in IOP caused by …
1. narrow drainage angle between the cornea and iris
2. fluid cannot exit through trabecular meshwork/ schlemm’s canal

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14
Q

describe secondary open angle glaucoma

A

blockage of trabecular meshwork
e.g. cells/proteins, blood, tumour cells, corticosteroids

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15
Q

describe secondary closed angle glaucoma

A

narrowing /closure of angle
e.g. due to tumour pushing iris/lens forward, new blood vessels, forming fibrous tissue = restricting drainage

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16
Q

clinical features of glaucoma

A

enlarged cup with little neuroretinal ring

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17
Q

what is the treatment of glaucoma

A
  1. eye drops/topical
  2. systemic
  3. laser
  4. surgery
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18
Q

describe glaucoma eye drops/topical treatment

A
  1. prostaglandin analogues
  2. beta-blockers
  3. carbonic anhydrases inhibitors
  4. sympathomimetics
  5. miotics
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19
Q

describe glaucoma systemic treatment

A
  1. carbonic anhydrase inhibitors
  2. osmotics
20
Q

what is the mechanism of action of prostaglandin analogues

A

increase uveoscleral outflow to increase drainage and decrease IOP

21
Q

what are the side effects of prostaglandin analogues

A
  1. red eye
  2. pigmentation - iris/skin/lash thickening/lengthening
22
Q

name examples of prostaglandin analogues

A

latanoprost
bimatoprost
travoprost

23
Q

what is the prostaglandin analogues indication

A

ocular hypertension/glaucoma for the treatment of open angle glaucoma

24
Q

what is the mechanism of action of beta blockers eye drops

A

reduce aqueous production in the ciliary body

25
Q

what are the contraindications of beta blocker eye drops

A

asthma
COPD
heart block
bradycardia
heart failure

26
Q

what are side effects of beta blocker eye drops

A
  1. allergic conjunctivitis
  2. bronchospasm
  3. CV: bradycardia/ heart block/ hypotension
  4. lethargy
  5. glucose intolerance
  6. impotence
27
Q

what are examples of beta blocker eye drops

A

timolol
levobunolol

28
Q

what is the mechanism of action of carbonic anhydrase inhibitor

A

decrease aqueous humour production in ciliary body

29
Q

what are the contraindications of carbonic anhydrase inhibitors

A
  1. sulphonamide sensitivity
  2. liver failure (acetazolamide)
  3. renal failure (acetazolamide)
30
Q

what are the side effects of carbonic anhydrase inhibitors

A
  1. topical burning/ watery eyes
  2. allergic conjunctivitis
  3. systemic:
    - lethargy/depression
    - metallic taste
    - metabolic: hypokalaemia
    - blood dyscrasia
31
Q

what the examples of carbonic anhydrase inhibitors

A

topical:
- dorzolamide
- brinzolamide

systemic:
- acetazolamide (IV/PO)

32
Q

name acetazolamide interactions

A

thiazide diuretics - profound hypokalaemia

33
Q

name the mechanism of action of alpha-2 agonists

A
  1. decrease aqueous production
  2. increase uveoscleral outflow
34
Q

name side effects of alpha-2 agonists

A
  1. allergic conjunctivitis
  2. systemic
    - bradycardia/ hypotension
    - insomnia/irritability
    - GI disturbances
35
Q

name which glaucoma drug at high risk of allergic conjunctivitis

A

alpha-2 agonists

36
Q

name examples of alpha-2 agonists

A

brimonidine
apraclonidine

37
Q

what are the MOA of apraclonidine

A

temporary lowering IOP causing increase side effects

e.g. allergic conjunctivitis and red eye

38
Q

what is the mechanism of action of miotic

A
  1. contraction of ciliary muscle = opens trabecular meshwork = increasing trabecular outflow
  2. iris constriction may pull the iris away from angle
39
Q

what are the side effects of miotics

A
  1. sweating/salivation
  2. nausea
  3. headache
  4. bradycardia
40
Q

name examples of miotics

A

pilocarpine

41
Q

what is the mechanism of action of osmotics

A

water drawn out of vitreous into blood by gradient = decreasing vitreous volume = lowering IOP

42
Q

name side effects of osmotics

A

cardiovascular/ fluid overload
urinary retention

43
Q

name contraindications of osmotics

A

cardiac disease/ heart failure

44
Q

name examples of osmotics

A

IV mannitol
oral glycerol

45
Q
A