Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

YR 3 Eye Disease and Therapeutics > Mydriatics > Flashcards

Mydriatics Flashcards

1
Q

why would you use a mydriatic?

A
  • enables a more thorough examination of the eye eg peripheral crystalline lens, vitreous, fundus
  • facilitates a stereo fundus exam
  • for treatment eg uveitis - stops iris sticking to the lens, preventing an increase in IOP
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

when would you use a mydriatic?

A

1) px at risk of ret detachment - high myopia (>5D), family, trauma

2) Symptoms - unexplained vision loss/ VF loss/ disturbance or floaters, flashes, veils, shadows

3) Screening - diabetics, hig myopia, prior to ocular surgery

4) Inadequate fundus view - lens/media opacities, miotic pupils (less than 2mm)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what to do prior to dilation

A
  • good reason to use the drug
  • explain procedure
  • px consent
  • issue written information
  • adverse effects - glare, loss of stereo vision, driving, operating machinery
  • minimise risk of adverse reaction
  • check for contraindications
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

how to instil and what to record

A

having explained the procedure and obtained th epx consent
- ask the px to look up
- pull down lower lid
- instil one drop into lower conjunctival sac
- occlude puncta - avoids drug draining into the nasolacrimal duct thereby reducing the effectiveness of the drug in the eye and increasing th elikelihood of causing systemic signs and symptoms
- record drug, strengt, dosage, exp date, batch no, and time of instillation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

general contraindication of mydriatics

A
  • known hypersensitivity to the drug
  • iris clip IOLS - not common
  • narrow angles - check for vh
  • px with symptoms suggestive of sub acute or chronic closed angle glauc
  • px with diagnosed CAG
  • px using pilocaarpine for glauc treatment (constricts pupil which opens up drainage channels) - wouldnt want to use it in these pxs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

symptoms of closed angle glacoma

A
  • blurred vision
    -halos
  • headache
  • painful
  • vomiting/nausea
  • photophobia
  • closed angle
  • fixed mid dilated pupil
  • cloudy cornea
  • conjunctival hyperaemia
  • sudden increae in IOP (usually >40mmHg)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

how to minimise risk of CAG

A

1) IOP - take pre and post dilation
- significant rise in IOP/ asymmetric rise
- monitor rise in IOP
- refer to eye casualty if continues to rise

2) Check anterior angles
- gonioscopy, van herrick, others

3) Existing symptoms
- ask if already has signs of angle closure eg halos around light, painful eye

4) Use of miotic drug
- not generally used in optometric practise

5) Any allergies to the drug/ previous reactions?

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

van herricks technique

A
  • used to estimate ant chamber depth
  • microscope normal to corneal apex
  • illumination at 60 degrees to microscope
  • narrow slit beam 1mm
  • low mag (16x)
  • compare width of ant chamber to width of corneal section
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

muscarinic antagonists/ antimuscarinic/ anticholinergic

A

tropicamide - most commonly used
cyclopentolate - rarely used as a mydriatic
atropine - only available to independent prescribers, unlikely to be used as mydriatic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

name a drug that is a sympathomimetic/ alpha agonist

A

phenylepherine - used more in USA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

ANS (parasympathetic)

A

Transmitter = acetylcholine
receptor = muscarinic
muscles = ciliary and sphincter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

ANS (sympathetic)

A

transmitter = noradrenaline
receptor = alpha
muscle = dilator

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

inducing mydriasis

A

inner circular muscle = iris sphincter muscle = pupilary constrictor
- parasympathetic stimulation causes contraction of the iris sphincter muscle and constriction of the pupil - blocking Ach causes dilation = tropicamide

outer radial muscle = iris dilator muscle = pupilary dilator
- sympathetic stimulation of the adrenergic receptors causes the contraction (shortening) of the iris dilator muscle and subsequently dilation of the pupil - pretends to act as noradrenaline = phenylephrine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

antimuscarinic action

A
  • iris sphincter muscle is controlled by parasympathetic innervation
  • paralysis of parasympatheitc nervous system inhibits the action of Ach
    produces: mydriasis, cycloplegia, reduced tear secretion - px may complain eye feels dry after instillation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

sympathomimetic action

A
  • noradrenaline is the transmitter in the sympathetic system
  • neurohumoral transmitter at most sympathetic postganglionic neuro effector junctions
    exceptions - sweat glands and vasodilator fibres on skeletal muscle

alpha and beta receptors
- mainly alpha 1 receptors in dilator pupillae muscles
- aplha 1 excitatory, alpha 2 inhibitory
- beta 1 excitatory, beta 2 inhibitory

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

tropicamide duration

A

mydriasis - 15 mins
recovery - 8-9 hrs
light reflex absent
induces a mild cycloplegic effect
may cause rise in IOP but likely to be transitory
few contraindications

17
Q

tropicamide availability

A
  • pom for use and supply by all optoms
  • single use - 0.5% and 1% tropicamide HCL minims (B&L), store below 25 degrees
  • multi dose containers, again 0.5 and 1% (alcon), store 2-8 degrees, protect from light
  • 1% sometimes used for darker irides but will also lead to an increased cycloplegic effect
  • pregnancy - avoid if poss, but better than using phenylephrine
  • women who are using tropicamide must not breast feed
18
Q

tropicamide side effects

A

ocular:
- transient stinging
- transient blurring
- photophobia
-raised IOP
- prolonged administration may lead to irritation, hyperaemia, oedema, conjunctivits

general body:
- CNS effects - dry mouth, reprted in children (blue eyes and blond hair)

19
Q

phenylephrine availabilty and its possible effects

A
  • p medicine
  • single use minims (B&L) - 2.5% and 10% phenylephrine HCL, store at 25 degrees, protect from light
  • 10% is contraindicated in children and elderly (>65 yrs) because of the increased risk of systemic toxicity
  • less effective on highly pigmented eyes
  • may cause widening of palpebral aperture
  • blanching of the conjuncitva - vasoconstriction of conj blood vessels
20
Q

phenylephrine contraindications

A
  • medication - cv problems eg anti hypertensives, tachycardia
  • medication - depression eg monoamine oxidase inhibitors, tricyclic antidepressants
  • thyrotoxicosis
  • insulin dependent diabetes
  • asthma
  • pregnancy/ lactation - may cause transient fetal hypoxia
  • use of pilocarpine - older px = pupil block, young px = accommodative spasm
21
Q

side effects of phenylephrine

A

ocular
- transient stinging
- transient blurring
- photophobia
- lid retraction
- conjunctival allergic reaction
- punctate keratitis

general body
- palpitations
- tachycardia
- cardiac arrhythmias
- htn
- h/as

drug gains access to systemic blood supply

22
Q

synergistic combinations

A
  • use of two or more substances to provide an effect greater than the sum of their separate effects
  • combinations of antimuscarinic and sympathomimetics can be considered (eg tropicamide 0.5 and phenylephrine 2.5)
  • allows lower conc of antimuscarinic to be used = less cyclo effect
23
Q

mydriasert

A

-pom
- insoluble opthalmic insert
- contains phenylephrine and tropicamide
- gradual release
- used pre operatively and diagnostically
- in adults - insert up to max 2 hrs before procedure, remove within 30 mins of mydriasis and within 2 hrs of application

24
Q

other mydriatic drugs

A

cyclopentolate ( antimuscarinic) - used to be available in 0.1%, cycloplegic ffects

homatropine (anti muscarinic)
- mydriatic effect commences in 10-20 mins
- maximal mydriasis 30-40 mins
- both light and accommodative reflexes absent
- recovery can take up to 3 days

YR 3 Eye Disease and Therapeutics (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions