Cycloplegics Flashcards
What is the mechanism of cycloplegics?
Antimuscarinic (parasympathetic)
Blocks cholinergic muscarinic receptors, ACh can’t bind so ciliary body and iris sphincter relax
What’s the dose for tropicamide?
1%, 2 drops
What’s the dose for cyclopentolate?
1%, 2 drops (3-5yo)
0.5%, 2 drops (>12 or light irides)
What’s the dose for homatropine?
1%
What’s the dose for atropine?
1%, 1 drop am and pm for 48 hours before exam and on am of exam
What’s the onset and duration for tropicamide?
Onset: 30 mins
Duration: 6 hours
What’s the onset and duration for cyclopentolate?
Onset: 30 mins
Duration: 24 hours
What’s the onset and duration for homatropine?
Onset: 30-60 mins
Duration: 1-2 days
What’s the onset and duration for atropine?
Onset: 30 mins- a few hours
Duration: 24 hours-1 week
What other uses does atropine have?
Myopia management (not in UK)
Amblyopia management
Uveitis (relaxes ciliary muscle to stop pain and prevents posterior synechiae forming)
What allowances need to be made for loss of ciliary muscle tonus during cycloplegia? (general)
Adjustment to sphere (minus) due to poss abolishment of tonus by drug
What sphere adjustment needs to be made for atropine?
-1.00D
What sphere adjustment needs to be made for homatropine and cyclopentolate?
-0-0.50D
What sphere adjustment needs to be made for tropicamide?
0D
What are the ADRs for atropine and homatropine?
Dry throat
Reduced sweat
Dry skin
Flushed skin
Tachycardia (increased)
Constipation
Hallucinations-coma-death (toxic dose)
