Ocular Pharmacology Flashcards
List 2 disadvantages of ocular treatments applied directly to the eye
Any two of the following:
1) technically more difficult than taking a tablet
2) risk of damage to the eye
3) a limited volume can be administered
List 2 advantages of using ocular treatments applied directly to the eye
1) allows quick action at sight of the problem
2) minimises systemic effects
For how long should an individual keep their eye closed after administering eye drops?
30 seconds
If 2 types of eye drop are required how long should be left between administering the first and the second type of drop?
5 mins should be sufficient to allow the first to be absorbed without the second washing it away
When should you advise a patient to use eye ointments and why?
At night before bed as a common side effect is blurry vision
What is an adjuvant?
A substance which enhances the body’s immune response to an antigen
What is a squint?
A squint is defined by a permanent deviation in the direction of the gaze of one eye
What is a sympathomimetic and how does it act?
It mimics the effects of the sympathetic nervous system yet acting on alpha-1 receptors, causing mydriasis (pupillary dilation)
What is the most commonly used sympathomimetic?
Phenylephrine
Give 3 circumstances or groups of people in which phenylephrine is less effective and explain why
1) diabetes mellitus - muscles of the iris become less flexible
2) dark iris - phenylephrine will bind to the melanin rather than the alpha-1 receptors meaning more is required
3) elderly - general wear and tear of the iris sphincter muscles
What are the side effects of phenylephrine and what advice should be given to patients as a result
Photophobia (wear hat or sunglasses following the appointment)
Blurred vision (don’t drive/bring a companion)
Stinging on instillation
Acute glaucoma as the drug increases intraocular pressure (rarely)
Hypertension and arrhythmias (rarely)
How long does it take phenylephrine to take effect and how long do the effects last?
Achieve mydriasis in 60-90 minutes
Effects last for 5-7 hrs
What is an alternative to (or can be used in conjunction with) with sympathomimetics?
Antimuscarinics
Give examples of commonly used antimuscarinics and list them in order of potency (weakest to strongest)
Tropicamide 1% - first line and weakest
Cyclopentolate 0.5% - slightly stronger
Atropine - strongest (used least often in this setting)
What part of the nervous system controls accommodation?
Parasympathetic
On which structure of the eye do antimuscarinics take effect?
Ciliary body
List the differences between the action time and type of actions that Tropicamide and cyclopentolate perform
Tropicamide - effect in 15 mins, lasts 4-6 hrs
Cyclopentolate -effect in 30-60 mins, lasts upto 24 hrs (Helen Day suggests this causes cycloplegia - paralysis of ciliary body - and that Tropicamide does not although other sources say Tropicamide 1% does!)
What drops would you administer to a patient suffering from uveitis?
Cyclopentolate 0.5%, 1 drop every 6-8hrs.
It relieves the pain by paralysing the ciliary body