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
What are the side effects of antimuscarinics (Tropicamide, cyclopentolate, atropine)?
Same as those for sympathomimetics (stinging on instillation, raised intraocular pressure, photophobia and blurred vision)
Plus - dry mouth, flushing, confusion
What are the symptoms of acute-angle closure glaucoma?
Red, painful eye Blurred vision Nausea and vomiting Headache (Exacerbated by mydriasis, is fairly rare but is a medical emergency)
How do parasympathomimetics act?
They mimic the effect of ACh on muscarinic receptors (open up drainage channels in trabecular meshwork)
What is the physiological effect of parasympathomimetics on the pupil?
They reverse mydriasis in around 30 mins and last for around 6hrs
What is the principle parasympathomimetic?
Pilocarpine
Suggest a good ocular drug to treat glaucoma
Pilocarpine
List 4 possible side effects of pilocarpine
Headache / browache
Burning / stinging on instillation
Myopia
Risk of retinal detachment
What type of drug will inhibit the production of aqueous humour?
Beta-blockers e.g. Timolol
Carbonic anhydrase inhibitors e.g. Acetazolamide (po or IV) or Dorzolamide (topical)
How do drugs such as Timolol and Dorzolamide treat glaucoma?
By reducing the production of aqueous humour and therefore reducing the intraocular pressure
Give 4 functions of the tear film in the eyes
Flush away debris
Antimicrobial protection (to an extent)
Optimise visual function
Lubricate eyelid movement
What is the first line treatment for dry eyes?
Hypromellose 0.3% (May also administer Ilube (acetylcysteine)to break down excess mucus)
Give three other possible treatments for dry eyes
Carbomers e.g. Viscotears
Polyvinyl alcohol e.g. Liquifilm tears
Lacrilube (ointment)
If prescribing Lacrilube when would you advise a patient to use it?
At nighttime as it can cause blurred vision, being very viscous
What are minims in relation to artificial tears and ocular lubricants?
They are single-use bottles which means they can be preservative-free which reduces risk of sensitivity to them
If you suspect a foreign body has entered an eye and caused damage what topical drug would you use to examine the eye
Fluorescein; yellow / orange dye highlights damage to the conjunctiva or cornea
Give 2 examples of anaesthetics you would use before a painful procedure on the eye e.g. Foreign body removal or ocular injection
Lidocaine or Proxymetacaine (no significant difference between the 2)
What is the first line treatment for superficial eye infections?
Chloramphenicol (particularly staph infections)
For how long should you continue treatment after infection clears?
48hrs (continue the 1drop every 2 hrs)
What does Chloramphenicol NOT treat?
Pseudomonas
What would be a good second line treatment for Staph infections?
Fusidic acid
Name 4 antibacterial preparations that will treat Staph infections and indicate which one of them will not also treat corneal ulcers
Ciprofloxacin
Levofloxacin
Ofloxacin
Gentamicin (only one that doesn’t also treat corneal ulcers)
List some common conditions that can cause dry eyes
(Results from a deficiency in any of the 3 tear film layers - outer lipid layer, middle aqueous layer or inner mucin layer)
Alterations in hormones e.g. Menopause, pregnancy, contraceptive pill
Rheumatoid arthritis (autoimmune inflammatory conditions)
Blepharitis (Staphylococcal or seborrhoeic)
How does blepharitis present?
Irritable, red, sticky eyes
Management = lid hygiene, antibiotics and artificial tears
List some causes of ptosis
Involutional (ageing) changes Third nerve palsy Myasthenia gravis Trauma to levator muscle Horner's Syndrome
What is the most common cause of visual loss?
Compression of the optic nerve (the optic disc may also be swollen or atrophic)
What are the most common affects of optic nerve compression?
Reduced visual acuity, colour vision loss and peripheral vision loss
What commonly causes diplopia (double vision)?
Misalignment of the eyes in straight ahead gaze or upon movement
A patient presents with a very painful left eye which is looking very red. He is complaining of hazy vision. On examination you notice the pupil of that eye is oval and non-reactive to light, you can detect no red reflex. What is he suffering from?
Angle closure glaucoma
