Mydratics

Question 1

What are mydriatics used for?

Answer 1

Dilation

Question 2

Why would you want to dilate a px?

Answer 2

Thorough examination, treatment to prevent the iris sticking to the lens

Question 3

When would a mydriatic be used?

Answer 3

-Highly myopic, FH of RD, trauma —> risk of RD
- Flashes, floaters, veils, shadows, unexplained vision loss/ disturbance —-> symptoms
- Diabetic px, prior to ocular surgery to ensure retina health —> screening
- Lens opacities, miotic pupils (pupils which are less than 2mm) —-> unable to get a proper fundus view

Question 4

Prior to dilation, what must you do?

Answer 4

1) Have a good reason for why you will be installing the drug
2) Explain to px the drug is going to sting and how you will be installing it
3) Get px consent
4) Advise the px side effects such as loss of stereo vision, cannot drive
5) Minimise risk of adverse reactions
6) Four Ds test
7) Check for contraindications

Question 5

What is the procedure of installing the drug?

Answer 5

1) Ask px to look up
2) Pull lower lid down
3) Instil one drop in
4) Occlude puncta—> increases effectiveness
5) Record four Ds

Question 6

What are the four DS

Answer 6

Expiry dates, drug, dosage, disposal

Question 7

What are contraindications to using mydriatic drug?

Answer 7

• Hypersensitive to the drug
• Narrow VH angle
• Sub-acute CAG
• CAG pxs
• Px using pilocarpine glaucoma treatment (this constricts pupil to open drainage angle

Question 8

What are some signs of a closed angle attack?

Answer 8

• Cloudy cornea,
• fixed mid-dilated pupil,
• closed angle,
• photophobia,
• conjunctival hyperamia,
• sudden IOP increase,
• haloes,
• headache,
• pain,
• nausea,
• blurred vision

Question 9

How do you minimise the risk of CAG attack?

Answer 9

• Measure IOPs before (if it significantly increases and does not decrease then refer to eye casualty)
• Check VH
• Any existing symptoms?
• Use of a miotic drug

Question 10

What are the two types of mydriatic drugs?

Answer 10

Muscarinic antagonists (antimuscarinic) and Sympathomimetic (alpha agonist)

Question 11

What are three examples of muscarinic antagonist?

Answer 11

1) Tropicamide (most common)
2) Cyclopentolate (not really used as a mydriatic)
3) Atropine (only IP optoms can give this)

Question 12

What is an example of a sympathomimetic mydriatic?

Answer 12

Phenylepherine

Question 13

What is the main objective of antimuscarinics?

Answer 13

Block acetylcholine on muscarinic receptors

Question 14

What is the objective of a sympathomimetic mydriatic?

Answer 14

Enhance the noradrenalin effects on alpha 1 adrenoceptors

Question 15

What is another way of describing the sympathetic nervous system and what muscle does it effect?

Answer 15

Fight or flight, dilator muscle

Question 16

What is another way of describing the parasympathetic nervous system and what muscle does it effect?

Answer 16

Inhibits body from overworking ‘rest and digest’, ciliary and sphincter muscle

Question 17

What does parasympathetic muscle contraction cause?

Answer 17

Constriction of the iris sphincter muscle and constriction of the pupil

Question 18

What does sympathetic muscle contraction cause?

Answer 18

Contraction of the iris dilator muscle

Question 19

What system is the iris sphincter muscle controlled by?

Answer 19

Parasympathetic nervous system

Question 20

What is the transmitter of the sympathetic nervous system?

Answer 20

Noradrenaline

Question 21

What is the time it takes for Tropicamide to work?

Answer 21

15 mins

Question 22

What is the recovery time of Tropicamide?

Answer 22

8-9 hours

Question 23

Does Tropicamide have a cycloplegic effect?

Answer 23

Yes, only mild though

Question 24

Are they many or few contraindications of Tropicamide?

Answer 24

Few

Question 25

What is the time it take for phenylephrine to work?

Answer 25

30 minutes

Question 26

How long does phenylephrine last for?

Answer 26

12-24 hours

Question 27

Is accommodation retained or not with phenylepherine?

Answer 27

Yes

Question 28

Are there many or few contraindications of phenylepherine?

Answer 28

Numerous contraindications

Question 29

What % is Tropicamide given?

Answer 29

0.5% or 1.0%

Question 30

Should Tropicamide be used for pregnant people?

Answer 30

Avoid if possible BUT not to people who breast feed

Question 31

What are side effects of Tropicamide?

Answer 31

• Stinging
• blurring
• photophobia
• raised IOP
• dry mouth

Question 32

What % is Phenylephrine available in?

Answer 32

2.5% and 10% (contraindication in children)

Question 33

What is a side effect which Phenylephrine causes in terms of the conjunctiva?

Answer 33

Cause blanching of the conjunctiva because of the vasoconstriction of the conjunctival blood vessels

Question 34

What test is Phenylephrine sometimes used to distinguish between two eye conditions?

Answer 34

Episclreitis and scleritis. If eyes whiten with it indicates episcleritis and if it doesn’t then it indicates scleritis.

Question 35

What are some contraindications to administrating phenylephrine?

Answer 35

• Cardio vascular problems
• Medication for depression
• Thyrotoxicosis (hyperthyroidism)
• Insulin dependent diabetes (type 1)
• Asthma
• Pregnancy/lactation; cause a transient feral hypoxia
• Use of pilocarpine (to avoid pupil block/accommodative spasm)

Question 36

What are ocular side effects of Phenylephrine ?

Answer 36

• Stinging,
• blurring,
• photophobia,
• lid retraction,
• conjunctival allergic reaction,
• punctuate keratitis

Question 37

What are general body side effects of Phenylephrine ?

Answer 37

• Palpitations,
• tachycardia,
• cardiac arrhythmias,
• hypertension,
• HAs

Question 38

What is an mydriasert and when would it be used?

Answer 38

Insoluble ophthalmic insert which contains phenylephrine and Tropicamide and is used pre-operatively