glaucoma Flashcards

1
Q

what is gonioscopy ?

A

used to evaluate eye’s drainage angle
anterior chambre angle

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2
Q

what is the pathology behind glaucoma ?

A

chronic progressive optic neuropathy resulting in progressive irreversible vision loss
|
increased intraocular pressure
|
loss of retinal ganglion cells causing disc cupping
|
associated visual field loss

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3
Q

what are the main subtypes of glaucoma ?

A

open angle glaucoma
angle closure glaucoma
secondary glaucoma
congenital glaucoma

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4
Q

what is normal tension glaucoma ?

A

a subtype of primary open angle glaucoma

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5
Q

where is the aqueous humor produced ?

A

ciliary bodies, specifically by pars plicata

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6
Q

what is the normal pathway of the aqueous humor ?

A

1.after being secreted by the ciliary bodies
2.passes from the posterior chamber to the anterior chamber
3. in front of the lens , via the pupil
4. drained at the trabecular meshwork at the angle of anterior chamber
5. passes through the canal of schelmn

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7
Q

what is the course of open angle glaucoma ?

A

chronic and slowly progressive

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8
Q

what is the presentation of open angle glaucoma ?

A

silent condition
usually asymptomatic

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9
Q

what are the risk factors associated with open angle glaucoma ?

A

increased intra-ocular pressure
aging
positive family history ( 1st degree relatives)
afro-caribbeans
central corneal thickness less than 555
high myopia, diabetes or hypeeertension
eye injury or surgery

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10
Q

what examinations are to be performed on a glaucoma patient ?

A

fundus examination
tonometry
gonioscopy
humphry visual field

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11
Q

what is the management stratergy for open angle glaucoma ?

A

halt optic nerve damage by reducing IOP

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12
Q

what are the treatment options regarding open angle gluacoma ?

A

medications
laser
filtration surgery

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13
Q

what are the different medications that can be usedd for open angle glaucoma ?

A

prostaglandin analogue
beta blocker
selective a2 receptor agonist
carbonic anhydrase inhibitor

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14
Q

why are prostaglandin analogues used ?

A

first line treatment
to increase uveoscleral outflow

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15
Q

which prostaglandins are used ?

A

latanoprost and bimatoprost

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16
Q

what are the side effects of using prostaglandin analogues ?

A

pigmentation
increase eyelash length
stinging sensation

17
Q

what are the contraindications to using beta blockers ?

A

timolol
in asthmatics, COPD and heart block

18
Q

what is the mechanism of action that occurs when using beta blockers in glaucoma ?

A

reduction on aqueous humor production

19
Q

what selective a2 receptor agonist is used ?

A

brimonidine

20
Q

what are the side effects associated with selective a2 receptor agonists ?

A

lethargy
dry eyes
dry mouth
allergy

21
Q

what is the mechanims of action associated with carbonic anhydrase inhibiitors ?

A

reduced production of aqueous humor
dorzolamide
brinzolamide

22
Q

why is high myopia associated with an increased chance of glaucoma ?

A

due to the increased axial length which lead to tilting of the optic disc and hence the optic nerve putting it at a higher risk of damage

23
Q

what surgeries are performed for open angle glaucoma ?

A
  1. trabeculoplasty to provide an alternative pathway for the passage of the aqueous humor
  2. trabeculectomy to insert a shunt
24
Q

what are the risk factors associated with angle closure gluacoma ?

A

hypermetropia
cataracts
mydriatics
abnormal iris configuration
asian ethnicity
elderly females

25
what are mydriatics ?
eye drops that dilate the pupil
26
how does an abnormal iris configuration cause a closed angle ?
1.plateau iris syndrome , on dilatation the iris folds into the angle and blocks the trabecular meshwork 2.. pupillary block - iris adhered to the lens blocking the flow of the aqueous humor ( posterior synechiae)
27
what are the symptoms of angle closure gluacoma ?
sudden onset of pain blurred vision colored halos around light frontal headache nausea and vomiting
28
what are the signs associated with closed angle glaucoma ?
IOP more than 40 mmgh corneal oedema limbal hyperemia fixed mid-dilated pupil shallow anterior chamber closed angle on gonioscopy
29
what is the normal IOP ?
11-21 mmhg
30
what is the systemic treatment for angle closure glaucoma ?
refer to opthalmologist - medical emergency 1. IV Carbonic anhydrase inhibitor (CAI) Acetazolamide 500mgs. 2. PO Acetazolamide 500mgs 3. Anti-emetics 4. IV mannitol or Oral glycerol
31
what is the definitive treatment for angle closure glaucoma ?
peripheral laser iridotomy lens extraction (to open the angle and deepen the AC) surgical trabeculectomy or iridectomy
32
what are the three methods of drainage of aqueous humor in the eye ?
trabecular outflow ( 90% ) uvoscleral drainage iris
33
what is the key modifiable factor in glaucoma ?
intra-ocular pressure
34
what is the normal cup:disc ratio ?
0.3
35
what is the cup: dic ration in glaucoma ?
more than 0.7 is usually indicative of glaucoma
36
what is the cup and what is the disc ?
cup : head of optic nerve dic : neuro-retinal rim