22 Mydriatics And Miotics Flashcards
(15 cards)
Why dilate
More light enters eye so clearer view
Greater area of retina seen
Binocular view possible
Indications of mydriatic
Myopia>-6, Hx RD, flashes and floaters, sudden loss of vision
Cataract
Diabetes
Headache
Contraindications of mydriatics
Narrow angles
Pseudophakia
Allergy, incompatible systemic med
Corneal disease
Premydriatic checks
Hx of previous effects and fam hx of glaucoma
Pre and post IOP
AC angle
Parasympathetic system
Drugs that affect the system apart from agonist and antagonist
Carbacol increases Ach release
Physostigimine inactivates Cholinesterase
Botulinum toxin blocks Ach release
How does tropicamide work and give onset max response and recovery
Blocks Ach at mAchRs
Onset 15 min max response 30min recovery at 4-6hrs
Contraindications to tropicamide
Brain damaged children
Down’s syndrome
Allergy
Narrow angle
How does phenylephrine work
Onset max Resp and recovery
Direct acting adrenergic agonist so binds to alpha 1 receptors in dilator, vascular yew of conjunctiva and mullers muscle
Onset 10 min
Max 60-90 min
Recovery 5-7 hrs
Local adverse effects of phenylephrine
Pain, lacrimation
Keratitis tho rare
Iris pigment release
Endothelial change in compromised corneas
Pxs contraindicated for phenylephrine
Insulin dependent diabetics as may be supersensitive to adrenergic agonist
Thyroid over activity - over active sympathetic system causing hypertensive crisis
Drugs that have vasopressor activity as makes BP way too high
- MAOI, TCA, Methyldopa, Reserpine, Guanethidine, a2 agonist
Why would you avoid pilocarpine in inflammatory glaucoma
Increases inflammation
Increases risk of iris bombe
Increases risk of posterior synechiae
What drugs directly activate Ach receptors for sphincter
And what blocks it
Plactivate pilocarpine muscarine
Block atropine tropicamide cyclopentolate
When is physostigimine or neostigimine used
Treat myasthenia graves and anticholinergic toxicity
Glaucoma as long lasting miosis
Problems in cholinergic agonist
Ciliary spasm
Conj hyperaemia
Headache and ocular pain
Pupil block in hyperopic eyes….?
Thymoxamine is used to reduce mydriasis and cycloplegia
How effective in mydriasis vs cycloplegia
Mydriasis reversal is a lot more quicker than pilocarpine
BUT cyclo reversal is a little bit quicker
