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OP2205 > 8. Mydriatics, Cycloplegics & Mitosis 1 > Flashcards

8. Mydriatics, Cycloplegics & Mitosis 1 Flashcards

1
Q

What is meant by entry level drugs?

A

Groups of drugs that can be used and provided by ALL optometrists.

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2
Q

2 cases where mydriatics are used?

A
  1. Pupil dilation- used to examine retina, lens periphery or vitreous.
  2. Ophthalmologist: in inflamed eyes to treat anterior uveitis treatment.
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3
Q

What factors affect mydriatics drugs effectiveness?

A
  1. Drug type, dose and contact time.
  2. Patient age - old pxs have smaller pupils.
  3. Iris colour- darker pigmented colours have a slower response due to pigment.
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4
Q

2 mechanisms of mydriatics?

A
  1. Sympathomimetics (Adrenergic agonist)
  2. Antimuscarinics (muscarinic antagonists)
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5
Q

Which muscle is stronger iris sphincter or iris dilator?

A

Iris sphincter muscle

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6
Q

Antimuscarinic mydriatics act on which nervous system?

A

Parasympathetic nervous system

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7
Q

Mechanism of Antimuscarinic mydriatics

A

Iris sphincter muscle relaxes and pupil opens. This drug is an antagonists to Ach it competes with it and blocks it. Causing iris sphincter to relax and open the pupil.

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8
Q

Mechanism of sympathomimetic mydriatics

A

Causes iris dilator to contract and open the pupil.

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9
Q

Dilated pupils still retain some light sensitivity, why?

A

Because iris sphincter muscle is stronger the iris dilator muscle and there is still some constriction in bright light.

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10
Q

2 examples of mydriatic drugs?

A
  1. Phenylephrine
  2. Tropicamide
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11
Q

Phenylephrine and Tropicamide, state the mechanism they work on?

A
  1. Phenylephrine- sympathomimetic - iris dilator constricts
  2. Tropicamide - anti muscarinic- iris sphincter relaxes
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12
Q

Phenylephrine vs Tropicamide which drug is also a vasoconstrictor?

A

Phenylephrine hence it also acts on smooth muscles.

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13
Q

Phenylephrine vs Tropicamide magnitude of dilation

A

Tropicamide is better

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14
Q

Dose of tropicamide used?

A

1-2 drops of 0.5% with 5 min intervals and darker coloured iris 1%

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15
Q

Dose of phenylephrine used?

A

1-2 drops of 2.5% with 5 min intervals

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16
Q

Phenylephrine vs Tropicamide onset and duration

A

Tropicamide quick onset, lasts for a shorter duration

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17
Q

Phenylephrine vs Tropicamide which one is preferred in practice to dilate a px?

A

Tropicamide

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18
Q

Mydriasis meaning

A

Dilation of the pupil

19
Q

Phenylephrine vs Tropicamide, which drug has a better magnitude to dilation?

A

Phenylephrine

20
Q

What are MIMIMS?

A

Preservative- free single dose eye drops

21
Q

What is mydriasert?

A

Combination of Phenylephrine and Tropicamide.
This drug comes in small sterile twisters that is placed in the lower conjunctival sac to give a slow release of drug to diffuse to the tear film and start the work.

22
Q

Combination of Phenylephrine and Tropicamide benefit?

A

Gain greater depth of mydriasis

23
Q

4 contraindications of using mydriatics?

A
  1. Cases of known hypersensitivity.
  2. Cases of known angle- closure.
    3.
23
Q

4 contraindications of using mydriatics?

A
  1. Cases of known hypersensitivity.
  2. Cases of known angle- closure.
  3. Exceptionally narrow angles.
  4. Patients with iris-mounted IOLs.
24
Q

Why does the risk of angle-closure glaucoma exists in use of mydriatics?

A

Due to blockage of the drainage of aqueous in some patients. Dilation can push the iris into the angle that can cause mechanical blockage.

25
Q

2 cautions when using mydriatics?

A
  1. Pregnancy
  2. Soft contact lens wearers
26
Q

Use of Phenylephrine and Tropicamide incase urgently required in pregnant women?

A

Phenylephrine: Should never be used in pregnant women because it causes vasoconstriction.
Tropicamide: Can be used if benefits outweigh risk e.g when a investigation must be carried out.

27
Q

Contact lens wear in relation to concentration of mydriatics?

A

Due to CL wear Px can have a minor punctate epithelium staining- this can enhance permission of the drug. In such cases 0.5% is used instead of 1%. Or 1 drop used instead of 2.

28
Q

5 contraindications of using phenylephrine?

A
  1. Known cardiac disorders
  2. History of stroke or very high BP
  3. Type 1 diabetes
  4. Taking adrenergic antagonists or monoamine oxidase inhibitors
  5. Pregnancy

BECAUSE: IT CAN CAUSE INCREASE IN BP IN PXs.

29
Q

What do you need to warn PXs about when using tropicamide?

A

Stings on installation, can cause blurred vision & glare. Effects can take several hours to wear off, can’t drive after drops and bring sunglasses on a sunny day.

30
Q

Mydriatics are Synergistics, what does this mean?

A

Can be used in combination with Phenylephrine

31
Q

Mydriatics can cause CNS effects, why?

A

Drug can be absorbed systemically from the tropical eye drops and lead to adverse effects.

32
Q

Why is cycloplegic drugs used in cycloplegic refraction?

A

Because it causes relaxation of ciliary body and reduces ability to accommodate.

33
Q

2 indication of using cycloplegic drugs?

A
  1. Cycloplegic refraction
  2. Suspected accommodative esotropia
34
Q

Overlap between cycloplegic and mydriatic drugs?

A

Some mydriatic drugs cause cycloplegia. Whereas, all cycloplegic drugs cause mydriasis.

35
Q

Mechanism for cycloplegic drugs?

A

They all have the same mechanism.
They work on the parasympathetic system. They block Ach effects and end plates on the ciliary muscle as well as iris sphincter muscle.

36
Q

Is tropicamide a mydriatic or cycloplegic action?

A

It is a mydriatic drug with some weak cycloplegic actions.

37
Q

4 drugs with cycloplegic actions in terms of decreasing strength?

A

Atropine -> Homatropine-> Cyclopentolate -> Tropicamide

38
Q

Is cycloplegic drug an entry level drug?

A

No- only used by IP OPTOMS

39
Q

Conc of cycloplegic used in minims and bottles?

A

1%
One drop used in the morning and 2 in the evening prior to examination plus a drop prior to the examination in the morning.

40
Q

Onset of cycloplegic drug?

A

30 mins to 1 hour.
Gradual recovery over 24 hours to 1 week

41
Q

3 other uses of atropine?

A
  1. Treatment of uveitis
  2. Treatment of myopia
  3. Treatment of amblyopia
42
Q

ADRs of Atropine?

A
  1. Dry throat
  2. Decreased sweating
  3. Dry skin, flushing
  4. Tachycardia
  5. Constipation, death
43
Q

ADRs to Atropine is said to be self- limiting, what does this mean?

A

Effects disappear once the drug is eliminated from the body.

OP2205 (8 decks)

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