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opthamology > acute glaucoma > Flashcards

acute glaucoma Flashcards

1
Q

drainage of aqueous humor

A
  • Aqueous humor is produced by the ciliary
    body in the posterior chamber of the eye

►It diffuses from the posterior chamber,
through the pupil, and into the anterior
chamber

►From the anterior chamber, the fluid is
drained into the vascular system via the
trabecular meshwork and Schlemm canal
contained within the angle

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2
Q

what is glaucoma

A

Glaucoma is a group of conditions with characteristic optic nerve head changes associated with corresponding visual field defects, with or without raised intra ocular pressure

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3
Q

How does glaucoma affect vision?

A
  • Glaucoma is the main cause of irreversible blindness in the world.
  • Damage to the optic nerve affects the peripheral vision initially and then gradually causes total sight loss if left untreated.
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4
Q

what is normal IOP

A

Normal range is quoted as 10 to 21 mmHg with a mean of 16mmHg

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5
Q

gold standard test to measure IOP

A

Goldmann Applanation Tonometry (GAT)

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6
Q

medical ways to reduce IOP

A 
Beta blockers e.g. Timolol
 Miotics: e.g. Pilocarpine
 Prostaglandin Analogues e.g. Xalatan or Lumigan
 Alpha Adrenergics: e.g. Alphagan
 CAI e.g. Azopt
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7
Q

aetiology of acute angle closure

A
  • peripheral iris blocking the outflow of aqueous humour
    narrow irido-corneal angle
  1. Relatively anterior location of iris-lens diaphragm (plateau iris)
  2. Shallow anterior chamber
  3. Floppy iris
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8
Q

predisposing factors of acute angle closure

A

Predisposing factors

  1. Age average 60 years - lens growth ass with age
  2. F:M 4:1 (as shallower anterior chamber)
  3. 1/1000 Caucasians, 1/100 Asians
  4. Hypermetropia - long sightedness
  5. FHx
  6. pupillary dilatation
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9
Q

symptoms of acute angle closure

A
  • sudden onset of a painful red eye
  • headache
  • nausea and vomiting
  • decreased vision
  • coloured haloes around lights (corneal oedema)
  • Photophobia
  • fixed or sluggish, semi dilated, irregular, oval shaped pupil
  • hard and tender to palpate
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10
Q

signs of acute angle closure

A
  • semi-dilated non reactive pupil
  • loss or red reflex
  • ciliary injection
  • corneal oedema
  • shallow Anterior chamber
    Flare in AC
    raised IOP
    tense on palpation
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11
Q

Post trabeculectomy complications

A

Iritis
Blebitis
Sudden increase or sudden decrease in IOPs

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12
Q

treatment for acute angle closure

A 
Medical: to lower the
pressure IOP
beta blockers 
 Topical steroid
 Iopidine
 pilocarpine
 Iv acetazolamide
 Surgical: Laser iridotomy
(curative in most cases)
 Prophylactic to other eye
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13
Q

symptoms of open angle glaucoma

A

develops painlessly and insidiously over time

characterised by a slow rise in intraocular pressure: symptomless for a long period
typically present following an ocular pressure measurement during a routine examination by an optometrist

  • peripheral visual field loss - nasal scotomas progressing to ‘tunnel vision’
  • decreased visual acuity
  • optic disc cupping
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14
Q

screening in open angle glaucoma

A

cupping of the optic disc

visual field loss particularly peripheral field

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15
Q

if there is a hereditary risk for glaucoma what should one do

A

screening from 40 years and onward

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16
Q

pathophysiology of open angle glaucoma

A

trabecular meshwork is not working

creased resistance to aqueous outflow, causing increased IOP

17
Q

risk factors for open angle galucoma

A
  • genetics: first degree relatives of an open-angle glaucoma patient have a 16% chance of developing the disease
  • black patients
  • myopia
  • hypertension
  • diabetes mellitus
  • corticosteroids
18
Q

fundoscopy of signs of primary open angle glaucoma

A
  1. Optic disc cupping - cup-to-disc ratio >0.7 (normal = 0.4-0.7), occurs as loss of disc substance makes optic cup widen and deepen
  2. Optic disc pallor - indicating optic atrophy
  3. Bayonetting of vessels - vessels have breaks as they disappear into the deep cup and re-appear at the base
  4. Additional features - Cup notching (usually inferior where vessels enter disc), Disc haemorrhages
19
Q

Ix for open angle galucoma

A
  • automated perimetry to assess visual field
  • slit lamp examination with pupil dilatation to assess optic neve and fundus for a baseline
  • applanation tonometry to measure IOP
  • central corneal thickness measurement
  • gonioscopy to assess peripheral anterior chamber configuration and depth
  • Assess risk of future visual impairment, using risk factors such as IOP, central corneal thickness (CCT), family history, life expectancy
20
Q

treatment for primary open angle glaucoma

A

first line: prostaglandin analogue (PGA) eyedrop

second line: beta-blocker, carbonic anhydrase inhibitor, or sympathomimetic eyedrop

if more advanced: surgery or laser treatment can be tried

21
Q

example of prostaglandin analogues

A

lantantoprost

22
Q

MOA of prostaglandin analogues

adverse effects

A

Increases uveoscleral outflow

once daily

brown pigmentation of the iris
increased eyelash length
periocular pigmentation

23
Q

example of beta blockers used for glaucoma

MOA

CI

A

timolol
betaxolol

reduces aqueous production

Should be avoided in asthmatics and patients with heart block

24
Q

examples of sympathomimetics

MOA

A

brimonidine
alpha 2 adrenoreceptor agonist

Reduces aqueous production and increases outflow

Avoid if taking MAOI or tricyclic antidepressants

Adverse effects include hyperaemia

25
Q

example of carbonic anhydrase inhibitors

A

dorzolamide

Reduces aqueous production

26
Q

examples of mitoics

MOA

SEs

A

pilocarpine
a muscarinic receptor agonist

Increases uveoscleral outflow

Adverse effects included a constricted pupil, headache and blurred vision

27
Q

what is goniotomy

A

surgery for congenital glaucoma

28
Q

signs of open angle glaucoma

A

increased intraocular pressure
visual field defect
pathological cupping of the optic disc1

29
Q

case findings of open glaucoma

A
  • optic nerve head damage visible under the slit lamp
  • visual field defect
  • IOP > 24 mmHg as measured by Goldmann-type applanation tonometry
  • if suspected full investigations are performed

opthamology (16 decks)

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