Mydriatics Flashcards
What are mydriatic drugs used for ?
Induce Pupil dilation
What is function of pupil?
regulate amount of light entering the eye and reaching retina
List purposes of using mydriatic drugs
- obtain better view of fundus
- therapeutic use in anterior uveitis - breaking posterior synechia
- get iris out of way in surgical procedure
List indications for using mydriatic drugs
- ocular dysfunction - reducation in VA , doubt about the cause
- stereoscopic view required
- Pts at risk of ocluar disease , RD in high myopes
What sx may a pt present with that would indicate you would need to do a dilated fundus exam
flashing light and increased floaters
Advantages of optoms using mydriatic drugs include
- Large FOV
- 3d view of retina
- peripheral exam of retina
- peripheral exam of lens and vitreous
explain the pharmacological methods of mydriasis
- blockage of parasymtphamic branch of ANS
- stimulate sympathetic branch of ans
- combination of antimuscarinic and sympathomimetic in eye
List pre dilation checks that should be carried out in a pt
Measure ... IOP AC angles VA pupil responses previous adverse/allergy to drug 4d test other contraindications - IRIS FIXATED IOL preganancy ? discuss tasks that need to be avoided
List post dilation checks …
IOP AC angles VA pupil response Given written material to pt
contraindications of using mydriatic drugs
- previous allergic reaction
- narrow AC angles
- iris fixated IOL
What should be discussed with your pt when using a mydriatic drug?
why u are putting drops in effect of drug how long effect will last tasks that should be avoided possible side effect what do to inacse of ADR
what is the key risk you should be mindful of when using a mydriatic drug on a pt
acute angle closure glaucoma
sx of acute angle closure glaucoma …
Headache
haloes around lights
nausea
ocular pain
At pt at risk of angle closure will have a van hericks ratio of
1.0.25 or less
Grade 2
How would you know if a patient is at risk of angle closure galucoma
check IOP post dilation and increase in 5mmHg unilateral - treat with suspicion
What mydriatic drugs are available to optoms ?
Tropicamide
Phenylephrine hydrochloride
What concentration is tropicamide avail in
0.5 and 1%
What is the legal classification of tropicamide
POM
What concentration in Phenylephrine hydrochloride in
2.5 and 10%
Legal classification of phenylephrine hydrochloride is
P
How does tropicamide work in the eye
antimuscarinic agent
competitive antagonist for muscarinic receptors
prevents acetylcholine binding - prevents contraction of sphincter muscle - unopposed action of dilator muscle = causes dilation
Tropicamide drug type :
Mydriatic and cycloplegic
Tropicamide Onset
15-20mins
Recovery of Tropicamide
6-8 hours
After how long does the dilation begin to wear of off tropicamide
after 2H
In which situation would u use the conc available of tropicamide
0.5% - commonly used in all pts - good mydriases and minimal cycloplegia
1% - pts with high melanin pigmentation in iris
Reversal of tropicamide can be done with
2% Pilocarpine - stimulates PNS
not avail to optoms
risk of psuedomyopia
Phenylephrine hydrochloride works by
stimulating Sympathetic branch
- sympathomimetic drug
acts directly on a1 adrenoreceptors , stimulates the radial muscles of iris = causes dilation
what effects does PH have on the eye
- blanching of conj blood vessels - whiter due to narrowing of vessels
- increased palpebral aperture due to stimulation of mullers muscle
- pupil dilation - asymmetric ?
State pupil reflex of when using Tropicamide and PH on eye
T- wont get reponse when light shone in eye , will stay dilated
PH - pupil will close up as sphincter muscle is unaffected
onset of PH
approx 1 Hour
Recovery of PH
3-4 Hours
reversal of PH
Thymoxine
not avail - blocks SNS
antagonist
List contraindication for USE OF PH
8
Indication for using phenylephrine hydrochloride
fundus photogrpahy
use in isolation when moderate dilation req
sector dilation
state other uncommon mydriatics
cyclopentolate hydrochloride ‘
cocaine
hydroxy amphetamine
cocaine was historically used to investigate
horners syndrome
onset of recovery of cocaine and hydroxyamphetamine
20-40 mins , last 6 hours
45 mins , lasts 3-6 hours
