Anaesthetics

Question 1

Are topical anaesthetics POM?

Answer 1

Yes

Question 2

What are the indications of use of anaesthetics?

Answer 2

• Contact tonometry
• CLs fitting
• FB removal
• Gonioscopy
• Lacrimal procedures

Question 3

What are three advantages of anaesthetics?

Answer 3

1) Allows for certain procedures to be carried out
2) More comfortable px
3) Make procedures easier for practitioner

Question 4

What are some disadvantages of anaesthetics?

Answer 4

1) Sting
2) Delayed healing
3) Eye more susceptible to damage
4) Repeated instillations may be required

Question 5

In terms mode of action, how do anaesthetics work?

Answer 5

Reversibly block sodium channels so an action potential cannot be created as depolarisation cannot occur.

Question 6

What properties of anaesthetics allow it to diffuse rapidly through the lipid membrane?

Answer 6

It is both lipophillic and hyrdophobic, and charged and uncharged

Question 7

Name three ester link anaesthetics and their durations

Answer 7

1) Oxybuprocaine (Benoxinate) - 15 mins
2) Tetracaine (Amethocaine) - 20 mins
3) Proparacaine (Proxymetacaine)- 15 mins
These are HYDROLYSED by choloinesterase

Question 8

What is the issue with ester link anaesthetics?

Answer 8

They break more easily than amide bonds (shorter duration) and are common with allergic reactions

Question 9

What is an example of an amide link anaesthetic?

Answer 9

Lignocaine (Lidocaine) -30 mins
This is RESISTANT to hydrolisation and has a longer duration.

Question 10

What is Amethocaine (Tetracaine HCl) good for?

Answer 10

FB removal due to deep anaesthesia

Question 11

What % does Amethocaine (Tetracaine HCl) come in and how should it be stored?

Answer 11

0.5% ad 1.0% minims, it should be stored below 25 degrees

Question 12

What is the most widely used anaesthetic?

Answer 12

Oxybuprocaine HCl (Benoxinate)

Question 13

What are some contraindications of Oxybuprocaine HCl (Benoxinate)?

Answer 13

• Due to bactericidal properties, careful when administrating it in hospital if you have just taken a culture
• Known allergy
• Premature babies
• Pregnancy/ breast feeding

Question 14

What % does Oxybuprocaine HCl (Benoxinate) come in and how should it be stored?

Answer 14

0.4% minims and stored below 25 degrees

Question 15

Which drops sting the least?

Answer 15

Proxymetacaine Hydrochloride

Question 16

What are some pros of Proxymetacaine Hydrochloride ?

Answer 16

Minimal punctate corneal staining and least antibacterial properties

Question 17

What % does Proxymetacaine Hydrochloridecome in and how should it be stored?

Answer 17

0.5% minims and stored between 2-8 degrees in a refrigerator

Question 18

What % does Lidocaine Hydrochloridecome in and how should it be stored?

Answer 18

4% combined with 0.25% fluorescein minims and store below 25 degrees

Question 19

Name six side effects of anaesthetics.

Answer 19

1) Transient stinging
2) Transient blurring
3) Conjunctival hypermia
4) Mild superficial damage
5) Punctate keratitis
6) Hypersensitivity reactions (mild conjunctival)

Question 20

What are some precautions that should be mentioned when using anaesthetics?

Answer 20

1) Enhances effects of other drugs as permeability of epithelium cells increased
2) Px must be informed to not rub their eye
3) Healing delayed
4) Open to abuse
5) Young children