Practical 1: Drugs on the eye

Question 1

which type of nervous system plays a role in the control of processes in the eye

Answer 1

the autonomic nervous system

Question 2

describe what happens to the eye under bright conditions

Answer 2

parasympathetic nerve impulse
circular muscles (of iris) contract
radial muscles relax
pupil constricts
less light enters eye

Question 3

pupil constriction involves which neurotransmitter and receptor

Answer 3

acetylcholine released from parasympathetic nerve endings will bind to muscarinic M3 receptors causing the circular muscles of the iris to contract

Question 4

describe what happens to the eye under dim light

Answer 4

sympathetic nerve impulse 
circular muscles relax 
radial muscles contract
pupil dilates 
more light enters the eye

Question 5

which neurotransmitter and receptor are involved in pupil dilation

Answer 5

adrenaline is released from sympathetic nerve endings and binds to alpha-adrenoreceptors causing the radial muscles of the iris to contract

Question 6

when clinicians want to examine the retina in detail what eye drops do they use

Answer 6

eye drops that are antagonists at muscarinic receptors to dilate the pupil

Question 7

the autonomic nervous system also allows the eye to accommodate for near vision. How

Answer 7

by adjusting the curvature of the lens via the ciliary muscle and the suspensory ligaments

Question 8

describe accommodation when focusing on distant objects

Answer 8

the ciliary muscles relax to allow the suspensory ligaments to pull on the lens, making it thinner

Question 9

describe accommodation when focusing on near objects

Answer 9

the ciliary muscles contract releasing tension on the suspensory ligaments allowing the lens to bulge more

Question 10

contraction of the ciliary muscle is controlled by which type of nervous system and neurotransmitter

Answer 10

parasympathetic nervous system anf acetylcholine

Question 11

what type of drugs will affect the ability of the eye to accommodate

Answer 11

drugs which are agonists or antagonists at the muscarinic M3 receptors

Question 12

this is a band 2 practical, which means

Answer 12

medical supervision is required

Question 13

can contact lens users take the eye drops

Answer 13

soft lenses: no unless they take them off and keep them out until the class is over. could be gas permeable and concentrate the drug out of solution and then act as a reservoir 
hard lenses: can use

Question 14

students driving or cycling after can take

Answer 14

phenylephrine but not tropicamide or pilocarpine

Question 15

what are contraindications

Answer 15

we must ensure drugs do not effect any pre-existing medical conditions students possibly have

Question 16

what are cautions

Answer 16

must ensure drugs don’t increase the risk of unwanted effects in certain students eg pregnant or diabetics

Question 17

what are interactions

Answer 17

must ensure drugs don’t interact with any medicines students may be taking

Question 18

when giving the eyedrops why should the patient avoid blinking

Answer 18

blinking cuases the medication to flow into the nasolacrimal duct

Question 19

how else can we aso minimise drainage of the drug into the nasolacrimal duct

Answer 19

occluding ( blocking) the punctum after instillation of the drug

Question 20

what is the pupil gauge used for

Answer 20

to measure pupil size

Question 21

what is the pen torch used for

Answer 21

to measure pupillary response to light, speed of response

Question 22

what is the near point rule used for

Answer 22

to measure near vision

Question 23

what are reading books used for

Answer 23

to see which passage is read the most comfortably

Question 24

what is the Snellen test used for

Answer 24

successfully read off the chart. 6/

Question 25

phenylephrine is basically adrenaline so the drug is a parasympathetic/sympathetic antagonist or agonist

Answer 25

dilation- sympathetic agonist

Question 26

for pilocarpine what were the results and therefore what kind of drug is it

Answer 26

pupil constriction and vision change, parasympathetic agonist

Question 27

for tropicamide the results were a dilated pupil, from this we can deduce two types of drugs that tropicamide could be which are

Answer 27

sympathetic agonist or parasympathetic antagonist

Question 28

tropicamide involves a paralysed ciliary body so it is a

Answer 28

parasympathetic antagonist

Question 29

when tropicamide and pilocarpine were added there was extreme dilation of the pupil, how can we tell which drug has a higher affinity

Answer 29

tropicamide ( the parasympathetic antagonist) is more effective than pilocarpine ( parasympathetic agonist) which has a lower efficacy and lower affinity

Question 30

how would you distinguish between a sympathetic agonist and parasympathetic antagonist

Answer 30

if the ciliary body is affected, if the ciliary body is paralysed, parasympathetic antagonist but f the ciliary body is involved and works then it is a sympathetic agonist