Diagnostic Drugs 1&2 Flashcards
(30 cards)
What is the purpose of mydriatic drugs in optometry?
Mydriatic drugs are used to dilate the pupil, often when the view to the fundus is restricted.
What are the two main categories of mydriatic drugs?
Antimuscarinics and Sympathomimetics.
Give an example of an antimuscarinic mydriatic drug and its properties.
Tropicamide (0.5% and 1% concentrations). It has an onset of 20-25 minutes, recovery in 4-6 hours, and causes blurry vision and photophobia.
What are the risks associated with mydriatic drugs?
The major risk is Acute Angle Closure Crisis (AAC), which involves pain, nausea, vomiting, blurred vision, and halos around lights.
How do you minimize the risks associated with mydriatic drugs?
Pre-dilation checks, including measuring IOP, checking anterior chamber angles, and ensuring informed consent. Also, assess the patient’s history for any previous intermittent attacks of blurred vision or eye ache.
What is the role of phenylephrine as a mydriatic drug?
Phenylephrine (2.5% and 10%) is used to dilate the pupil with minimal cycloplegic effect. It can be combined with tropicamide for enhanced activity.
What are cycloplegic drugs used for in optometry?
Cycloplegic drugs paralyse accommodation (focusing ability) to obtain an accurate refractive error measurement.
Name an example of a cycloplegic drug and its effects.
Cyclopentolate (0.5% & 1%). It has an onset of 40 minutes and recovery can take up to 24 hours.
What is the difference between mydriatics and cycloplegics?
Mydriatics primarily dilate the pupil, while cycloplegics relax accommodation, paralysing the focusing ability of the eye.
What is the general use of topical anaesthetics in optometry?
Topical anaesthetics are used to numb the eye for diagnostic procedures like foreign body removal, intraocular pressure measurement, and tonometry.
List some commonly used topical anaesthetics.
Proxymetacaine, Oxybuprocaine, Lidocaine, and Tetracaine.
What is the onset and recovery time for topical anaesthetics?
The onset is typically 30-60 seconds, and the effect lasts up to 25-30 minutes.
What are diagnostic dyes used for in optometry?
Diagnostic dyes are used to assess the ocular surface for damage, such as corneal abrasions, and to evaluate conditions like dry eye.
What is the role of sodium fluorescein as a diagnostic dye?
Sodium fluorescein stains damaged areas of the cornea, useful in detecting corneal abrasions and assessing dry eye disease.
How is sodium fluorescein administered?
It is available as paper strips containing 1mg of fluorescein or as aqueous drops (1% or 2%).
What is the difference between sodium fluorescein and lissamine green in diagnostic use?
Lissamine green is more specific for staining dead or devitalized cells and mucous strands, used in dry eye assessments, while sodium fluorescein highlights corneal damage.
What is dry eye disease and how is it assessed?
Dry eye disease is a multifactorial condition involving tear film instability, ocular surface inflammation, and damage. It can be assessed using diagnostic dyes like sodium fluorescein and lissamine green.
What are artificial tear substitutes used for?
Artificial tear substitutes are used to relieve symptoms of dry eye disease and lubricate the ocular surface.
Name some types of artificial tear substitutes.
Aqueous-based (e.g., sodium chloride, hypromellose), lipid-based (e.g., soya bean oil, castor oil), and gel-based preparations.
How do topical anaesthetics work at the cellular level?
They block pain signals by inhibiting sodium channels in the nerve cell membranes, preventing the initiation and propagation of action potentials.
What should optometrists consider when administering mydriatic drugs?
Optometrists must consider factors like patient history, skin/hair/iris pigmentation, and the risk of side effects like AAC. They must also monitor pupil diameter and check IOP before and after administration.
How does cyclopentolate affect accommodation?
Cyclopentolate paralyzes accommodation by acting on the ciliary muscle, making it easier to assess refractive error without interference from the patient’s focusing ability.
When should tropicamide not be used?
Tropicamide should not be used in patients with a history of angle closure glaucoma or in those at risk of developing it.
