Ocular Pharmacology Flashcards
Benefits of applying treatments to the eye for ocular disorders?
Quick action at the site of the problem
Minimises systemic side effects
Negatives of applying treatments to the eye for ocular disorders?
More technically difficult than taking a tablet
Limitations of site of administration include risk of damage and limited volume
How long to wait between instilling drops if several?
5 minutes
Problems with eye drops
Administration
Poor compliance in a condition with no visible symptoms
Unpleassant side effects, e.g. stinging on admin, blurred vision
SE developing over time, e.g. sensitivity
Other methods of applying drugs to the eye
Intravitreal injection
Inserts
Spray, eye wash
Systemic treatment
Which autonomic nervous system makes the pupil dilate?
Sympathetic
What do sympathomimetics do?
Act on alpha-1 receptors
Cause mydriasis in 60-90 mins and lasts 5-7 hours
e.g. phenylephrine
Side effects of Phenylephrine?
Photophobia and blurred vision
Stinging on instillation
Acute glaucoma
Hypertension and arrythmias
What do antimuscarinics do?
Block action of ACh at muscarinic receptors
Cause mydriasis
note: parasympathetic NS also controls accomodation
Give examples of antimuscarinics used in ocular therapy?
Atropine
Cyclopentolate
Tropicamide
What is cycloplegia?
Loss of the ciliary muscle resulting in a loss of accomodation
What therapeutic effect does tropicamide have?
Mydriasis
When is cyclopentolate used?
To induce cycloplegia
For uveitis
- Immobilised iris and relaxes ciliary muscle
Side effects of antimuscarinics?
Stinging on instillation
Raised intra-occular pressure
Photophobia and blurred vision
Dry mouth, flushing, confusion
How do you check if pupils are fully dilated?
Using a pen torch, pupils should not dilate any more?
What are the symptoms of acute angle closure glaucoma?
Red painful eye
Blurred vision
N&V
Headache
What do parasympathomimeics do?
Mimic effect of ACh on muscarinic receptors
Open up drainage channels in trabecular meshwork
Reverse mydriasis in around 30 mins - lasts 6 hours
Give an example of a parasympathomimetic?
Pilocarpine - used to treat glaucoma
Side effects of pilocarpine?
Headache/browache
Burning/stinging on instillation
Myopia (short-sighted)
Risk of retinal detachment
What are beta-blockers used for in ocular therapy?
Inhibit aqueous humour production
Give an example of a beta blocker used for ocular therapy?
Timolol
Name carbonic anyhydrase inhibitors
Acetazolamide (po / iv)
Dorzolamide
Give examples of artificial tears and lubricants
Hypromellose - supplements aqueous layer
Carbomers (e.g. viscotears)- thixotrophic to prolong retention
Polyvinyl alcohol (e.g. liquifilm tears) - surfactant, good replacement for mucin layer
Ointments (e.g. lacrilube) - highly viscous so long lasting, causes blurred vision
What agent would be used to show up areas of damage to conjunctiva or cornea?
Fluorescin
