L5

Question 1

What is local anaesthetics

Answer 1

local anaesthetic ar local agent that produce surface anaesthetic when applied.

it occur without loss of consciousness

Question 2

what is the basic chemical structure of LA

Answer 2

weak bases consisting lipophilic group connected by an intermediate chain (ester/ amide) to an ionizable group

Question 3

What does lipophili section of LA determines

Answer 3

potency, duration of action, potential toxicity

Question 4

what is the basic nerve conduction (+) potential

Answer 4

influx of sodium into interior of nerve followed by efflux of potassium generated the action potential

Question 5

what is the basic nerve conduction @ rest

Answer 5

The nerve returns to it resting stage when Na+ and K+ are returned to their original sides: Na+ on the outside and K+ on the inside

Question 6

what LA do

Answer 6

LAs prevent the generation & conduction of nerve impulses by blocking sodium channels.

Question 7

what are the indication of LA in ocular

Answer 7

• fb removal
• goldman tonometry
• contact lens fitting
• schirmer’s test
• gonioscopy
• nasolacrimal duct probing and irrigation

Question 8

what are the common LA

Answer 8

tetracaine (est 20m)
alcaine (15m)
benoxinate (15m)

Question 9

what are the ocular side effects of LA

Answer 9

• momentary local stinging/ burning
• localised / difused epithelial desquamation. (commonly spk)

Question 10

what are the systemic side effect of LA

Answer 10

Toxicity affects CNS, cardiovascular & respiratory system.

HOWEVER V RARE

Question 11

when will systemic side effect of LA occurs

Answer 11

large dosage,
rapid absorption
liver/kidney disease/ damage

Question 12

what are the precaution for use of LA

Answer 12

• NO HOME USE
• CORNEA abrasions will not heal properly in the presence of LAs. Epithelial regeneration is slowed
• REPEATED DROPS = CORNEAL STAINING (DUE TO loosen epithelial cells )
• use weakest conc possible
• make sure px do not rub eye under LA

Question 13

what are the type of staining agents

Answer 13

NaFl
Rose bengal
alcian blue
Trypan Blue
Lissamine Green

Question 14

How does NaFl works

Answer 14

Exhibits fluorescence when cobalt light is absorbed The dye absorbs light in the blue range of the visible spectrum, with absorption peaking at 490nm (blue) ,then emits light at 530nm (yellow).

Question 15

what is nafl susceptible to

Answer 15

bacterial contamination, esp Pseudomonas aeruginosa.

Question 16

what is the indication for NAFL

Answer 16

1. ASSESSMENT of epithelial integrity - detect abrasion, ulcer, dessication, surface irregularities. it will sink into stroma if there are area of epithelial loss/ intraepithelial junction loss
2. CL fitting
3. Applanation tonometry

Question 17

how to use rose bengal

Answer 17

Pink/magenta in colour when viewed with white light

Stains degenerated or dead cells, mucous strands (vital dye)

Question 18

what are the uses of rose bengal

Answer 18

Diagnosis of dry eye
Abrasions
ulcerations etc.