Introduction to Diagnostic Drugs Flashcards
What are mydriatics?
Drugs used to dilate the pupil
Why is there an increased use of mydriatics in optometric practices?
- Expansion of co-management schemes (shared care schemes)
- There is an increase in professional negligence cases so stronger evidence of diagnoses is needed.
- Better appreciation of the benefits of dilation.
When would you dilate a pupil?
- When px have Conditions such as e.g. diabetes, uveitis, pigmented fundus lesion, suspected glaucoma, peripheral retinal degeneration, hypertension (high blood pressure), cataract, age-related macular degeneration, history of retinal detachment, history of metastatic cancer.
- If Px shows Symptoms of e.g. flashes and floaters, new distortion, unexplained loss of vision, recent blunt force trauma.
- When there is a Relevant family ocular history
- When Px has Small pupils, nystagmus, unsteady fixation -Where stereoscopic view of retina is necessary
- To check Systemic medications with potential side effects
- To get good fundus photograph
- Generally, when you need to get a really good/better/stereoscopic view!
Is dilation important to spot conditions?
Arguably yes -A study found Ability of ophthalmoscopy to grade correctly diabetic retinopathy is more than 50% higher in dilated pupils than undilated pupils.
Which Mydriatics are typically used by optometrists (3)?
- Tropicamide 0.5%
- Tropicamide 1.0%
- Phenylephrine 2.5%
[Tropicamide is the most commonly used]
[All available in minims - basically single use plastic files - advantage is that they can all be kept sterile as a result]
When using any drug, the College of Optometrists guidelines state:
- Optometrists should record the batch number and expiry date of drugs that are used in their professional practice
- Also record drug name, concentration and time instilled (as different drugs have different recovery times).
This will facilitate verification that:
- Drug is in date,
- In the case of a drug recall – makes it easier to trace all patients who may have been affected
What precautions do we need to take before Mydriasis (before dilating pupil)?
- Explanation to patient:
- Why dilating,
- effects of dilation
- Duration of dilation
- Need to take note of Previous experience of dilation
- Need to take note of Medical history
- E.g. phenylephrine: caution in patients with cardiovascular disease, hypertension.
- Need to be aware of if it might be affected by Current medication or interfere with current medication
- Need to measurement of IOP and take an Assessment of risk of angle closure.
What is angle closure glaucoma?
A type of glaucoma in which the anterior chamber angle through which aqueous humour flows, becomes blocked.
What will happen to the patient in an acute attack of angle closure glaucoma (ACG)?
Px will be in pain
Px will experience red eye
Cornea looks hazy around edges.
Why are we so concerned with acute angle glaucoma when using mydriatics?
Theres evidence to suggest the two are linked.
Mydriatic drops may be linked to an acute attack of angle closure glaucoma.
If a patient has a suspected retinal detachment, wet AMD etc and you cannot obtain sufficient view - what must you do?
You must either dilate, or refer on worst case scenario.
What are tests that can be done to assess the risk of angle closure?
- Van Herick
- (Flashlight test)
- (Smith’s slit-length method)
- Methods using pachymeters)
- Gonioscopy
(Ones in brackets aren’t commonly used)
What advice do you give your patients regarding mydriasis?
- They will experience a Loss of acuity (blurriness their accommodation will be off)
- They might experience Glare problems (Biggest problem with drops):
- patient may benefit from wearing sunglasses
- patient may wish to bring sunglasses with them to the examination
- Px may experience Driving difficulties
- Make Px aware of symptoms of an acute ACG attack
- Give information sheet
ALWAYS GIVE WRITTEN AND VERBAL INFORMATION
What are the general guidlines for driving after dilation?
Patients should be given an information sheet, and recommended not to drive for the rest of the day.
College of Optometrists’ Information sheet says that “It is recommended that driving should be avoided whilst your vision is affected.”
What is tropicamide?
An anti-muscarinic drug which causes mydriasis by relaxing the sphincter muscle of the iris and cycloplegia by relaxing the ciliary muscle
What is cycloplegia?
The blocking of accommodation
What are the timings for tropicamide?
- Onset of action = approx 10 to 30 minutes
- Maximum effect = within approx 20 to 40 minutes
- Recovery to normal = approx 4 to 9 hours
- BUT INDIVIDUAL RESults are variable
