Pharmacology And The Eye Flashcards Preview

TAS Opthalmology > Pharmacology And The Eye > Flashcards

Flashcards in Pharmacology And The Eye Deck (37)
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1
Q

What prevents many systemic medications from reaching the intra-ocular tissues?

A

The blood-ocular barrier

2
Q

What is the result of most chemotherapeutic agents not being able to enter the eye?

A

Makes it a sanctuary site for cancer, particularly ALL

3
Q

Is absorption of topical therapy through the cornea good?

A

Yes

4
Q

What is the result of absorption of topical therapy through the cornea being good?

A

Most anterior segment problems can be treated with drops

5
Q

When is systemic therapy required for ocular problems?

A

Posterior segment disease

6
Q

When might drops not be tolerated?

A

When applied intensively, or when contact lenses are worn

7
Q

Why are many drops not tolerated when applied intensively or when contact lenses worn?

A

Due to preservatives in the drops

8
Q

What % of the active drug is absorbed into the eye when a drop is instilled in the eye?

A

10%

9
Q

What happens to the drug that is not absorbed into the eye when using drops?

A
  • Spills
  • Enters the systemic circulation via the conjunctival vessels
  • Enters nasal mucosa via the nasolacrimal ducts
10
Q

After what time is the peak plasma concentration of drugs administered by eye drops?

A

Within 30 mins

11
Q

Can drugs administered through eye drops cause systemic side effects?

A

Yes, particularly in neonates

12
Q

How should systemic side effects caused by eye drops be minimised?

A

The lowest concentration of active ingredient should be used, and the nasolacrimal duct was occluded with a fingertip for a couple of minutes after drop instillation

13
Q

What can prevent adequate examination of the eye?

A

Severe eye pain and blephrospasm

14
Q

What might be helpful when examining the eye when there is severe pain or blepharospasm?

A

Topical anaesthetics

15
Q

Should topical anaesthetics for the eye be used on a routine basis?

A

No

16
Q

Why should topical anaesthetics for the eye not be used on a routine basis?

A

Corneal anaesthesia prevents epithelial healing and risks infection

17
Q

What topical anaesthetics for the eye are in common use?

A
  • Proxymetacaine 0.5%

- Tetracaine 0.5%

18
Q

How long does proxymetacaine 0.5% last for?

A

10 minutes

19
Q

Why is proxymetacaine a good choice for children?

A

Does not sting

20
Q

What is the advantage of tetracaine 0.5%?

A

Longer lasting

21
Q

What is tetracaine useful for?

A

Surgical procedures

22
Q

What is the disadvantage of tetracaine 0.5%?

A

Severe stinging on instillation

23
Q

Why is flourescein useful for diagnosis?

A

It lights up areas of conjunctival and corneal epithelial loss if illuminated with blue lights

24
Q

Why can fluorescein light up areas of corneal and conjunctival epithelial loss?

A

Because it absorbs blue light and re-emits it in the green spectrum

25
Q

In what forms is fluorescein available?

A
  • Fluoret impregnated strip

- Eye drops

26
Q

What do anti-muscarinic eye drops do?

A

Block the parasympathetic innervation of the ciliary muscle and pupil sphincter

27
Q

What are anti-muscarinic eye drops commonly used for?

A

To allow accurate objective refraction in clinic

28
Q

What are the side effects of anti-muscarinic eye drops?

A
  • Stinging
  • Blurred vision
  • Photosensitivity
  • Flushing
  • Dry mouth
29
Q

What anti-muscarinic eye drops are used?

A
  • Tropicamide 1%
  • Cyclopentolate 1% (0.5% for infants)
  • Atropine 1%
30
Q

What is the onset of tropicamide 1%?

A

15 minutes

31
Q

How long does tropicamide active for?

A

3-6 months

32
Q

What is the onset of action of cyclopentolate?

A

20 minutes

33
Q

What is the duration of action of cyclopentolate?

A

24 hours

34
Q

What is the onset of action of atropine?

A

30 minutes

35
Q

What is the duration of action of atropine?

A

7 days

36
Q

What are sympathomimetic eye drops used for?

A

Used synergistically with anti-muscarinic eye drops for intense mydriasis needed for intra-ocular surgery or ROP screening and treatment

37
Q

What are the side effects of sympathomimetic eye drops?

A
  • Stinging
  • Blurred vision
  • Sensitivity to light

Rarely, tachycardia and hypertension can occur