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MPharm 2 - PH2113 > Unit 5 - Diabetes 5 > Flashcards

Unit 5 - Diabetes 5 Flashcards

1
Q

What is glaucoma?

A

Damage to the optic nerve resulting in deterioration of visual field caused by intra-ocular pressure being too high for normal functioning of optic nerve head

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2
Q

What is the cause of glaucoma?

A

Disease often associated with a disturbance in circulation of aqueous humour in the eye

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3
Q

What are the symptoms of glaucoma?

A

Raised intraocular pressure (IOP)

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4
Q

How is aqueous humour formed?

A

Clear fluid formed from blood
Filtered in ciliary process arterioles
Rate of formation = 2-3 uL/min
Total volume of aqueous humour = 125 uL

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5
Q

Which two enzymes are involved in the formation of aqueous humour?

A
  • ATPase

- carbonic anhydrase

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6
Q

How is aqueous humour made?

A
  1. Filtered in ciliary body
    - 75% active secretin
    - 25% ultrafiltration
  2. Flows into posterior chamber
  3. then into anterior chamber between lens and iris
  4. passes through trabecular meshwork
  5. drains via canal of schlemm
    - 60 - 90%
  6. into ocular veins
  7. also uveoscleral outflow
    - 10 - 40%
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7
Q

What is the normal intraocular pressure in the aqueous humour?

A

16 mmHg

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8
Q

What causes raised intraocular pressure?

A

Drainage and secretion not being balanced

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9
Q

What is the effect of raised intraocular pressure?

A

Restriction of blood supply to optic nerve
- back pressure
Optic nerve atrophy
Reduces field of vision

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10
Q

What is the field of vision in glaucoma?

A

Normal
Reduced field
Tunnel vision
Blindness

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11
Q

What does the type of glaucoma depend on?

A

Poor aqueous humour drainage
- degeneration and subsequent collapse of trabecular meshwork
- mechanical blockage of trabecular meshwork by peripheral role of iris
- flapping back
Increase in filtration pressure
- rare

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12
Q

What are the two types of primary glaucomas?

A

Open angle

Closed angle

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13
Q

What is secondary glaucoma?

A

Rise in intraocular pressure as a result of a known cause

  • inflammation
  • trauma
  • mechanical flapping back of iris
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14
Q

Describe primary open angle glaucoma (POAG)

A 
Most common
- 0.5% of population
Slow onset
- commonly high intraocular pressure
- pathological changes in trabecular meshwork may occur
> 40 years
Short sighted
> -6.00 dioptres
More common in Afro-caribbeans
- x 8 incidence
- 10-15 years earlier
- genetic predisposition
Possible association with diabetes mellitus
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15
Q

Describe primary closed angle glaucoma (PCAG)

A 
Blockage of trabecular meshwork
Can be ocular emergency
Symptoms
- dilated pupils
- pain and inflamed eyes
- blurred vision
- reflex nausea and vomiting
- loss of vision (24 hours)
- blindness (2 - 3 days)
Can be drug induced
- atropine
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16
Q

Describe secondary open angle glaucoma

A 
Occurs secondary to other conditions
Inflammation
- uveitis
- increased secretion of proteins and inflammatory mediators
Pigment dispersion syndrome
- pigment granules shed from iris and ciliary epithelium
- block and damage TM
Pseudoexfoliative syndrome
- flakes peel off iris
- block trabecular meshwork
Steroid-responsive glaucoma
- blockage of trabecular meshwork by glycosaminoglycans
- released in response to steroids
Trauma
- blunt
- penetrating trauma
- causes bleed from vessels in iris/ciliary body
- bleeding blocks trabecular meshwork
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17
Q

Describe secondary closed angle glaucoma

A 
Inflammation
- uveitis
- iris can be pushed forward and adhere to TM
Iris bombe
- increased posterior pressure
- iris bulges forward
Lens related
- cataract lens may swell and form synechiae
- adhesion between lens and iris
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18
Q

How is glaucoma diagnosed?

A

Examination of optic disc
Measurement of intraocular pressure
Gonioscopy

19
Q

How does the optic disc appear in glaucoma?

A 
Cupped
- depressed
White due to nerve fibre degeneration
- increased pressure may restrict blood supply
- anoxia causes degeneration
20
Q

Give two ways that the intraocular pressure can be measured

A

Contact tonometry

Air jet tonometry

21
Q

What is gonioscopy?

A

Viewing the irideocorneal angle via a mirror or prism

22
Q

What is the major aim of glaucoma treatment?

A

To prevent sight loss

23
Q

What drug groups can be used to treat glaucoma?

A 
Prostaglandin analogues
Sympathetic modifiers
Carbonic anhydrase inhibitors
Miotics
Osmotic agents
24
Q

What is the first line treatment of glaucoma?

A

Prostaglandin analogues

25
Q

How does Latanoprost work?

A

Increase uveoscleral outflow

26
Q

When should Latanoprost be administered?

A

In the evening

27
Q

What are the side effects of Latanoprost?

A

Possible change in eye pigmentation
Eye lash
- thickening
- lengthening

28
Q

When is Latanoprost contraindicated?

A

In pregnancy

  • contains prostaglandins
  • used in abortions
29
Q

What other prostaglandin analogues are used to treat glaucoma?

A

Latanoprost
Travoprost
Tafluprost

30
Q

Give an example of a prostamide used to treat glaucoma

A

Bimatoprost

31
Q

Which drugs are used to treat chronic open angle glaucoma?

A

Beta-adrenoceptor blockers

- timolol

32
Q

How do beta-adrenoceptor blockers treat glaucoma?

A

Block beta-2 receptors in afferent ciliary BVs
Vasoconstriction and decreased aqueous humour formation
- decreasing intra-ocular pressure

Block beta-2 receptors in ciliary process
Decreased ultrafiltration
Reduced intra-ocular pressure

33
Q

What are the side effects of Timolol?

A 
Bradycardia
Palpitation
Hypotension
Bronchospasm
- contraindicated in asthma
Fatigue
Impotence
34
Q

What are the ocular effects of Timolol?

A

Corneal anaesthesia

Blurred vision

35
Q

Give examples of beta-adrenoceptor blockers used to treat glaucoma

A 
Timolol
Betaxolol
Carteolol
Levobunolol
Metipranolol
36
Q

Give an example of alpha-2 adrenoceptor agonist used to treat open angle glaucoma and ocular hypertension (OHT)

A

Brimonidine

  • decrease aqueous secretion
  • increase uveoscleral outflow
37
Q

Give examples of carbonic anhydrase inhibitors used to treat open angle glaucoma and secondary glaucoma

A 
Acetazolamide
- non-specific CA inhibitor
Dorzolamide
- CA-II inhibitor
Brinzolamide
- CA-II inhibitor
38
Q

What is a miotic used to treat?

A

Closed angle glaucoma

39
Q

How does a miotic work to treat closed angle glaucoma?

A

Open up drainage channels in trabecular meshwork
Contract constrictor pupillae (circular)
- pulls iris away from trabecular meshwork

40
Q

Give an example of a miotic

A

Pilocarpine

41
Q

What are the side effects of pilocarpine?

A

Miosis
- poor night vision
Transient headache
- browache

Avoid use in inflammatory conditions

  • acute iritis
  • uveitis
  • secondary glaucoma
42
Q

How do osmotic agents treat glaucoma?

A

Increase extracellular osmolality

  • water leaves vitreous humour by osmosis into intravascular space
  • intraocular volume is decreased
  • decreases IOP
43
Q

Give an example of an osmotic agent used to treat glaucoma

A

Mannitol

- given in an emergency or before surgery

44
Q

What are the important points for opthalmic preparations?

A 
Sterility
Tonicity
- eye will tolerate NaCl (0.7 - 2%)
pH
- range 3.5 - 10.5 well tolerated in eye
Stability
- depends on pH and temperature

MPharm 2 - PH2113 (50 decks)

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