mydriatics, cycloplegics, anaethetics and stains Flashcards
why do we use mydriatics
- allows a more thorough examination of the eye e.g. peripheral crystalline lens, vitreous and fundus
- facilitates a stereo fundus exam
- for treatment
when do we use mydriatics
- on patients at risk of retinal detachment
- symptoms
what type of symptoms would a px show for us to use mydriatics
- unexplained vision loss/ vf loss or disturbance
- floaters, flashes, veils, shadows
what patients are at a risk of retinal detachment
- high myopia (> -5.00D)
- family history
- trauma
when else would we use mydriates
- screening: diabetes, prior to ocular surgery
- inadequate fundus view: lens/media opacities, miotic pupil
benefits of mydriatics
- rapid onset
- adequate duration
- fast recovery
- no adverse effects
- light reflex abolished
- no rise in IOP
what do we do prior to dilation
- ensure we have good reason to use the drug
- explain procedure
- px consent
- issue written information
- advise effects- glare, loss of stereo vision, driving, operating machinery
- minimise risk of adverse reaction
- check for contraindications
- 4D test: Drug, Dosage, Date, Disposal + time
method of instillation of myrdriatic
- ask px to look up
- pull down lower lid
- instill a drop into lower conjunctival sac
- occlude puncta to avoid drainage into nasolacrimal duct
- record drug, strength, dosage, expiry date, batch number and time of instillation
what are some general contraindications
- sensitivity to drug
- narrow angles
- if they have iris clip IOLs
- px with symptoms of sub-acute or chronic closed-angle glaucoma
- px diagnosed with CAG
- px using pilocarpine for glaucoma treatments
CAG after tropicamide; what symptoms would they have?
- blurred vision
- haloes
- headaches
- pain
- nausea
- photophobia
- closed angle
- fixed mid-dilated pupil
- cloudy cornea
- conjunctival hyperaemia
- sudden increase in IOP
checks to minimise risk of CAG
- IOP; pre and post dilation
- anterior angles
- existing symptoms
- reverse continued increase of IOP with miotic drug
examples of muscarinic antagonists mydriatics and how often used
tropicamide - mostly used
cyclopentolate - rarely used as mydriatic
atropine- unlikely to be used as mydriatic and only available to independant prescribers
examples of sympathomimetic mydriatics
phenylepherine - used more in USA
autonomous nervouse system branches
parasympathetics: inhibits body from overworking
sympathetics: fight or flight
what is the main transmitter in the parasympathetics nervous system
acetylcholine
