Primary Open Angle Glaucoma Flashcards

1
Q

What is glaucoma?

A

A group of eye conditions that lead to damage of the optic nerve and loss of retinal ganglion cells causing progressive loss of the visual fields usually due to raised intra-ocular pressure (IOP)

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2
Q

What can glaucoma be divided into?

A
  • Primary vs Secondary
  • Ope angle vs Closed angle
  • Acute or Acute-on-chronic or Intermittent or Chronic
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3
Q

What is primary open angle glaucoma characterised by?

A
  • Adult onset
  • IOP at some point > 21mmHg
  • Open iridocorneal angle
  • Glaucomatous optic neuropathy
  • Visual field loss compatible with nerve fibre damage
  • Absence of underlying cause
  • Usually bilateral
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4
Q

What is the primary problem in glaucoma?

A

Disease of the optic nerve

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5
Q

What is raised in most cases of glaucoma?

A

IOP

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6
Q

What causes raised IOP in open-angle glaucoma?

A

Reduced flow through the trabecular meshwork

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7
Q

What is the role of the trabecular meshwork?

A

To absorb the aqueous humour

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8
Q

How does the reduced flow through the trabecular meshwork in open-angle glaucoma progress?

A

As a chronic, painless, degenerative obstruction

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9
Q

What is the cause of primary open angle glaucoma?

A

There is no underlying cause (hence it’s called primary)😊

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10
Q

What are the risk factors for primary open angle glaucoma?

A
  • Age
  • Family history
  • Afro-caribbean
  • Ocular hypertension
  • Myopia
  • Retinal disease
  • Diabetes
  • Systemic hypertension
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11
Q

After what age does primary open angle glaucoma most commonly present?

A

65

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12
Q

What is myopia?

A

Short-sightedness

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13
Q

What retinal disease can increase the risk of primary open angle glaucoma?

A
  • Central retinal vein occlusion
  • Retinal detachment
  • Retinitis pigmentosa
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14
Q

Are the majority of cases of primary open angle glaucoma symptomatic or asymptomatic?

A

Asymptomatic

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15
Q

Why are the majority of cases of primary open angle glaucoma asymptomatic ?

A

Because initial visual loss is in the peripheral vision which is covered by the other eye

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16
Q

When do patient begin to notice visual loss with primary open angle glaucoma?

A

When loss is severe and affects the central vision

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17
Q

How may primary open angle glaucoma be detected?

A

When checking IOP and visual fields of people with affected relatives or during a routine eye check

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18
Q

What abnormalities may raise suspicion of primary open angle glaucoma during a routine eye check?

A
  • Abnormal disc
  • Raised IOP
  • Abnormal visual fields
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19
Q

How is primary open angle glaucoma clinically classified?

A
  • Mild
  • Moderate
  • Severe
  • End-stage
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20
Q

What is classified as mild primary open angle glaucoma?

A

Early visual field defects

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21
Q

What is classified as moderate primary open angle glaucoma?

A

Presence of arcuate scotoma (n-shaped visual field loss over central field) and thinning of the neuroretinal rim (cupping)

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22
Q

What is classified as severe primary open angle glaucoma?

A

Extensive visual field loss and marked thinning of the neuroretinal rim

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23
Q

What is classified as end-stage glaucoma?

A

Only small residual visual fields remaining with very little neuroretinal rim

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24
Q

What should assessment for primary open angle glaucoma involve?

A
  • Goinoscopy
  • Corneal thickness
  • Tonometry
  • Optic disc examination
  • Visual field testing
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25
Q

What is goinoscopy?

A

Used to measure iridocorneal angle to assess whether open or closed angle glaucoma

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26
Q

Why should corneal thickness be assessed when investigating primary open angle glaucoma?

A

It can influence the IOP reading, thickened cornea can cause erroneously high reading

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27
Q

What is tonometry (in glaucoma assessment)?

A

Objective measure of the IOP based on resistance of the cornea to an indent

28
Q

What is the normal range of IOP?

A

10-21mmHg

29
Q

Why is examining the optic disc important in assessing primary open angle glaucoma?

A

It is a direct marker of disease progression

30
Q

How is optic disc damage assess in primary open angle glaucoma?

A

By looking at the cup:disc ratio

31
Q

What is the normal cup:disc ratio?

A

0.3 (can be up to 0.7)

32
Q

What suggests glaucoma when looking at the optic disc?

A

Cupping with time rather than just cupping

33
Q

What are the differentials for primary open angle glaucoma?

A
  • Normal/low-tension glaucoma
  • Closed-angle glaucoma
  • High myopia
  • Ocular hypertension
34
Q

When should treatment for primary open angle glaucoma be started?

A
  • After consistent readings of high IOP

- If the disease is obviously advanced

35
Q

How is treatment for primary open angle glaucoma planned?

A

By setting a target IOP based upon the current degree of damage?

36
Q

How is a target IOP set in treatment for primary open angle glaucoma?

A

At the pressure at which further damage is unlikely to occur (usually a 30% drop from current IOP)

37
Q

What monitoring is regularly required in primary open angle glaucoma management?

A
  • IOP measuring
  • Visual field testing
  • Optic dis examination
38
Q

What is first line therapy type in primary open angle glaucoma?

A

Medical treatment

39
Q

What is usually the first choice drug therapy for treating primary open angle glaucoma?

A

Topical beta blocker and prostaglandin analogue

40
Q

What additional medications can be given in primary open angle glaucoma?

A
  • Sympathomimetics
  • Carbonic anhydrase inhibitors
  • Miotics
41
Q

How do prostaglandin analogues work to treat primary open angle glaucoma?

A

Increase aqueous outflow via the uveoscleral route

42
Q

What are the contraindications for use of prostaglandin analogues ?

A
  • Active uveitis

- Pregnancy and breast feeding

43
Q

When should caution be take for prescribing prostaglandin analogues?

A
  • Brittle or severe asthma

- Aphakia or pseudophakia

44
Q

What is aphakia?

A

No lens

45
Q

What are the potential side-effects of prostaglandin analogues ?

A
  • Change in eye colour
  • Brown pigmentation
  • Thickening and lengthening of eye lashes
  • Rarely; uveitis, ocular pruritus, photophobia and keratitis
46
Q

How do beta-blockers work to treat primary open angle glaucoma?

A

Aqueous secretions are reduced by inhibition of the beta-receptors on the ciliary body

47
Q

What are the contra-indications for the use of beta-blockers to treat primary open angle glaucoma?

A
  • Bradycardia
  • Heart block
  • Uncontrolled heart failure
  • Asthma
  • COPD
48
Q

When should caution be taken when prescribing beta-blockers for primary open angle glaucoma?

A
  • Depression
  • Myasthenia gravis
  • Some other medication used e.g. verapamil
49
Q

What are the potential side-effects of using beta-blockers to treat primary open angle glaucoma?

A
  • Irritation
  • Dry eyes
  • Blepharo-conjunctivitis
  • Bronchospasm
  • Bradycardia
50
Q

What is the action of carbonic anhydrase inhibitors to treat primary open angle glaucoma?

A

Reduce aqueous secretions by the ciliary body

51
Q

What are the contraindications for the use of carbonic anhydrase inhibitors in primary open angle glaucoma?

A
  • Renal impairment
  • Metabolite imbalance
  • Severe hepatic impairment
  • Breast-feeding
52
Q

When should caution be taken when using carbonic anhydrase inhibitors to treat primary open angle glaucoma?

A
  • Elderly
  • Hepatic impairment
  • History of renal calculi
  • History of intraocular surgery
  • Pregnancy and breastfeeding
53
Q

What are the potential side-effects of carbonic anhydrase inhibitors ?

A
  • Localised discomfort
  • Lacrimation
  • Topical allergy
  • Taste disturbance
  • Nausea/vomiting
  • Headache
  • Dizziness
  • Fatigue
54
Q

What is the action of sympathomimetics in treating primary open angle glaucoma?

A

Reduces aqueous secretion and increase outflow through the trabecular meshwork

55
Q

What are the contraindications for the use of sympathomimetics in primary open angle glaucoma?

A
  • Angle-closure glaucoma

- Monoamine-oxidase

56
Q

When should caution be taken when treating primary open angle glaucoma with sympathomimetics?

A
  • Hypertension

- Heart disease

57
Q

What are the potential side-effects of sympathomimetics?

A
  • Mydriasis
  • Dry eye
  • Severe smarting and redness of the eye
  • Lethargy
  • Hypotension
58
Q

What is the action of miotics in treating primary open angle glaucoma?

A

Open the drainage channels in the trabecular meshwork by ciliary muscle contraction

59
Q

What are the contraindications for using miotics to treat primary open angle glaucoma?

A
  • Uveitis

- Retinal holes

60
Q

When should caution be taken when using miotics to treat primary open angle glaucoma?

A
  • Retinal disease
  • Cardiac disease
  • Hypertension
  • Asthma
  • Peptic ulceration
  • Urinary tract obstruction
  • Parkinson’s disease
61
Q

What are the potential side-effects of miotics in treating primary open angle glaucoma?

A
  • Miosis
  • Localised discomfort
  • Sweating
  • Bradycardia
  • GI disturbance
62
Q

What treatment options may be considered if medical management of primary open angle glaucoma is unsuccessful?

A

Laser or surgical treatment

63
Q

What laser treatment options for primary open angle glaucoma are available?

A
  • Argon laser trabeculoplasty
  • Selective laser trabeculoplasty
  • Cyclodide laser trabeculoplasty
64
Q

What surgical treatment options are available for primary open angle glaucoma?

A
  • Trabeculectomy

- Artificial shunts

65
Q

When may primary open angle glaucoma affect ability to drive?

A

If it impacts visual fields

66
Q

What are the potential complications fo primary open angle glaucoma?

A
  • Visual loss