Ophthalmic Drugs

Question 1

Describe the sphincter pupillae muscles

Answer 1

Ring of smooth muscle fibres around the pupil that, when contracted constricts the pupil. Part of the parasympathetic system.

Question 2

The sphincter pupillae muscles are part of which system?

Answer 2

Parasympathetic system with ACh as the neurotransmitter

Question 3

Describe the dilater pupillae muscles

Answer 3

Thin layer of myoepithelium that extends from iris root to sphincter pupillae and when contracting allows for the pupil to dilate. Part of the sympathetic system.

Question 4

The dilater pupillae muscles are part of which system?

Answer 4

Part of the sympathetic system. Noradrenaline as the neurotransmitter

Question 5

What does the PNS do in relation to the eye?

Answer 5

Supplies the sphincter pupillae and ciliary muscle and constricts the pupil. It allows for accommodation.

Question 6

What does the Sympathetic nervous system do in relation to the eye?

Answer 6

Supplies the dilator pupillae within the iris and dilates the pupil

Question 7

What is the neurotransmitter in the PNS?

Answer 7

ACH is released from the nerve and binds to ACh receptors on the post-synaptic membrane.
Acetyl cholinesterase (enzyme) terminates the signal.
This is for nerve to nerve or nerve to muscle

Question 8

What is the neurotransmitter involved in the sympathetic nervous system?

Answer 8

Noradrenaline

Question 9

What is a parasympathomimetic drug?

Answer 9

It mimics ACh meaning it causes the action potential to be higher.
As it also is an agonist to the PNS it further increases the action potential

Question 10

What is a parasympatholytic drug?

Answer 10

It’s an anti-muscarinic meaning that it blocks ACh and thus stops the action potential of the parasympathetic innervation (ACh) and thus is an antagonistic

Question 11

What is a sympathomimetic drug?

Answer 11

Mimics noradrenaline in the sympathetic nervous system and so is an agronomic

Question 12

What is a sympatholytic drug?

Answer 12

Blocks noradrenaline

Question 13

What are the 4 names of ophthalmic drugs called?

Answer 13

Cycloplegic drugs, Mydriatic drugs, Miotic drugs and Local Anaesthetics

Question 14

What are cycloplegic drugs?

Answer 14

They’re parasympatholytic meaning that they inhibit ACh and thus cause temporary paralysis of the ciliary muscle, no accommodation occurs (cycloplegia) and causes pupil dilation (mydriasis) because the sphincter muscle is inhibited.

Question 15

When are cycloplegic drugs used?

Answer 15

For refraction in children and in myopia studies and are used to check the fundus

Question 16

What are the 3 cycloplegic drugs?

Answer 16

Cyclopentolate, Atropine and Tropicamide

Question 17

What is cyclopentolate?

Answer 17

It’s a cycloplegic drug that is the gold-standard for cycloplegia. It is faster-acting, non-toxic and doesn’t last long. It cannot be used for children <3mo but for between 3mo-12yo use 1% and then in >12yo use 0.5% quantities

Question 18

What is atropine?

Answer 18

It’s a cycloplegic drug that comes from deadly nightshade. It is used in 1% quantities.

Question 19

What is tropicamide?

Answer 19

It’s a cycloplegic drug that is most often used when wanting to dilate the pupil to check the fundus. it can also be used in refraction where there are allergies to cyclopentolate or atropine. Used in 0.5% or 1% quantities.

Question 20

What are mydriatic drugs?

Answer 20

Causes mydriasis which is dilation of the pupil as it is a sympathomimetic which means it enhances the action of Noradrenaline in the sympathetic system and so causes the enhancement of the dilator pupillae.

Question 21

When are mydriatic drugs used?

Answer 21

In adults for fundus exams.

Question 22

Why would we use mydriatic drugs instead of cycloplegics?

Answer 22

Cycloplegic drugs all are mydriatic drugs (cause dilation of the pupil) but sometimes we want mydriasis without significant cycloplegia

Question 23

What are the mydriatic drug?

Answer 23

Phenylephrine. It’s a sympathomimetic and agonist and not to be used in anyone with high blood pressure. it almost always uses 2.5% as the 10% version can impact the cardiovascular system.

Question 24

What would we do if we wanted maximum mydriasis?

Answer 24

Use a sympathomimetic and an anti-muscarinic/parasympatholytic

Question 25

What are miotic drugs?

Answer 25

They’re parasympathomimetic drugs meaning that they block the parasympathetic system ACh and so leads to miosis.
It can cause accommodative spasm and it opens the trabecular meshwork and improves aqueous drainage.

Question 26

What are miotic drugs used in?

Answer 26

Previously used in glaucoma but this is rare now. Some now use as presbyopia correction by utilising the pinhole effect of the constricted pupil

Question 27

What is an example of a miotic drug?

Answer 27

Pilocarpine Hydrochloride

Question 28

What are local anaesthetics used in?

Answer 28

Applanation Tonometry which is the measurement of intraocular pressure, involves a prove onto the cornea
OR
used in Gonioscopy to view the anterior chamber
OR
used in the forced duction test

Question 29

How are local anaesthetics used?

Answer 29

May be instilled prior to other drops as they reduce the stinging of cycloplegic drops, increase the effectivity of anti-muscarinic and patients must not rub eyes after as they scratch the corneal as unable to feel corneal sensations

Question 30

How does iris pigmentation affect certain drugs?

Answer 30

It can take longer to dilate the eyes/achieve cycloplegia in individuals with brown irises as the iris can absorb some of the drug molecules opposed to going to the muscle site (Lovasik, 1986).
Either the dark pigment cells bind to the drug which reduces drug uptake OR the anterior limiting layer of the iris is formed of chromatophores in darker eyes this is thicker and more compact so may block drug uptake.

Question 31

In a case history what do you need to take before administering an ophthalmic drug?

Answer 31

1) Current and previous general health issues
2) Current medications
3) Allergies
4) Whether they’ve had drops before and any adverse reactions to this

Question 32

What information do you need to provide a patient if administering them ophthalmic drugs?

Answer 32

1) Effect of drops/ointment
2) Side effects (minor)
3) Adverse reactions & where to go if they occur
4) Provide leaflets if available
5) That if using drops/ointment at home then to stop taking them if side effects occur

E.g. mydriatic drugs may be troublesome for a child due to the amount of light.

Question 33

How do we administer drops? Step-by-step

Answer 33

1) Wash hands
2) Gently pull down lower lid
3) If an adult, encourage them to look up
4) Drops into lower central fornix
5) Gently press on the tear duct area (punctual occlusion) as wanting to stop systemic absorption into the tear duct
6) Wipe away excess drops to prevent child getting drops on hands and putting fingers in mouth
7) Wash hands

Question 34

How do we administer ointment (oculentum)? Step-by-step.

Answer 34

1) Wash hands
2) Gently pull down lower lid
3) Squeeze approx. 0.5cm of ointment into lower central fornix
4) Massage lids gently
5) Wipe away excess ointment
6) Don’t allow child to rub eye and put fingers in mouth
7) Wash hands

Question 35

Why is ointment good in the night by less so during the day?

Answer 35

Good for long-lasting effects at night but it reduces VA

Question 36

What do we need to write in our notes?

Answer 36

1) Drugs used
2) Dosage
3) If instilled in the clinic we need to ask which eye and what time
4) If instilled at home we need to give clear instructions, let them know which eye(s), when, how frequent and when to stop
5) Report any errors or near misses

Question 37

Parasympathomimetic do what to the dilator, ciliary muscle and sphincter muscle?

Answer 37

Dilator - no effect

Ciliary Muscles - Enhances. Ciliary spasm, painful and blurred vision

Sphincter - Enhances (miosis)

Question 38

LOOK AT SLIDES

Question 39

Parasympatholytics/Anti-mucolytics do what to the dilator, ciliary muscle and sphincter muscle?

Answer 39

Dilator - no effect

Ciliary muscle - Blocks = lens wont change shape as ciliary muscle wont contract and thus results in cycloplegia (removal of accommodation)

Sphincter - Blocks = mydriasis (as the dilator isn’t affected and so has unopposed actions) and cycloplegia

Question 40

Sympathomimetic’s do what to the dilator, ciliary muscle and sphincter muscle?

Answer 40

Dilator - Enhances (mydriasis as the dilator is the strongest over the ciliary and sphincter as it’s enhanced) Accommodation isn’t affected as it doesn’t affect the PNS.

Ciliary Muscle & Sphincter - No effect

Question 41

Sympatholytic’s do what to do the dilator, ciliary muscle and sphincter muscle?

Answer 41

Dilator - Blocks = miosis as the sphincter muscle is unopposed

Ciliary Muscle & Sphincter - No effect

Question 42

Which drug would you use in a 13yo for refraction and fundus media check?

Answer 42

0.5% Cyclopentolate

Question 43

Which drug would you use in a 6mo for refraction and fundus and media check?

Answer 43

1% Cyclopentolate

Question 44

Which drug would you use for a 3yo with very dark eyes for refraction?

Answer 44

Local anaesthetics first and then 20 mins later 1 drop of cyclopentolate, then 20 minutes after do examination
OR maybe start 1 drop cyclopentolate, wait 20 minutes and do another drop if it didn’t work
OR straight to atropine and wait a few hours

Question 45

Which drug would you use for a 43yo for a fundus and media check?

Answer 45

Sympathomimetic - Phenylephrine (be aware of blood pressure history and general health with Pheny)