Introduction to diagnostic drugs Flashcards
what are the 3 main reasons for increased use of mydriatics in optometric practice
- expansion of co-management (shared care) schemes e.g. glaucoma schemes for primary open angle glaucoma
- increase in professional negligence cases, so need stronger evidence of diagnoses e.g. ‘missed retinal detachment’
- better appreciation of the benefits of dilation
list the 10 medical conditions with which you will dilate a patient
- diabetes
- uveitis
- pigmented fundus lesion - so can distinguish between a choroidal melanoma which needs treatment, or a naevus which is benign
- suspected glaucoma
- peripheral retinal degeneration
- hypertension - to check for haemorrhages or retinopathy
- cataract
- age related macular degeneration
- history of retinal detachment
- history of metastatic cancer
list the 4 symptoms with which you will dilate a patient
- flashes and floater
- new distortion
- unexplained loss of vision
- recent blunt force trauma - risk of retinal detachment
in which cases will dilation be required in practise
- relevant family ocular history
- small pupils
- nystagmus
- unsteady fixation
- where stereoscopic view of retina is necessary - using volk technique
- systemic medications with potential side effects
- to get a good fundus photograph
generally when you need to get a really good/better/stereoscopic view of fundus
what is a quantification of benefit of dilation with diabetic retinopathy
ability of ophthalmoscopy to grade correctly diabetic retinopathy is more than 50% higher through a dilated pupil than through an undiluted pupil
name the three types of mydriatics used by optometrists
- tropicamide 0.5%
- tropicamide 1.0%
- phenylephrine 2.5%
all available as minims - single use
what does the concentration of the drug depend on
the pupil group you are dilating
what is the college of optometrists guideline state for optometrists, when using any drug in practice
- optometrists should record the batch number and expiry date of drugs that are used in their professional practice
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
list 6 precautions which must be carried out before mydriasis
- explanation to patient
why dilating, effects and duration of how long it will last - previous experience of dilation
- medical history
e.g. phenylephrine: caution of patients with cardiovascular disease, hypertension (it can cause problems with) - current medication
- measurement of IOP
as biggest risk = causing onset of angle closure glaucoma if a person has a narrow anterior chamber as they have a higher risk - assessment of risk of angle closure glaucoma
what must you explain to a patient before carrying out mydriasis
why dilating, effects and duration of how long it will last
why is it important to ask a patient about their medical history before instilling phenylephrine
caution of patients with cardiovascular disease, hypertension (it can cause problems with)
why is it important to measure IOP before mydriasis
as biggest risk = causing onset of angle closure glaucoma if a person has a narrow anterior chamber as they have a higher risk
what happens in the eye with the case of angle closure glaucoma
where the front surface of the iris has come into contact with the trabecular meshwork and this causes a blockage of the angle through which aqueous fluid drains through the eye = no route for aqueous fluid to escape through the eye, causing pressure to rise to a dangerous level
how can dilation cause the angle to be blocked in the eye
the iris muscle tissue gets bunched up around the area of the angle hence can block the trabecular meshwork
what are the signs and symptoms of an acute attack of ACG
- red, painful eye
- cornea becomes hazy
- fixed pupil unresponsive to light
- aqeuous can’t drain out so IOP = 60-80mmHg
what did the baltimore eye survey do and discover when they dilated approx 5000 subjects in order to investigate the risk of mydriasis provoking an acute ACG attack
- used 1% tropicamide/2.5% phenylephrine
- discovered no ACG episodes
- later gonioscopy judged 20 of these to be at high risk i.e. had narrow angles (but no one experienced an ACG)
what is the risk of tropicamide (0.5% or 1%) in provoking an acute ACG attack
0 cases in 3972 dilations (safe to use)
what is the risk of all other dilating agents in provoking an acute ACG attack
33 cases in 600,000 dilations = 1 in 18,020 (risk is small)
what is the risk of dilating a patient with primary open angle glaucoma, in getting an acute ACG attack
0 cases in over 1000 patients
in what type of case does dilation facilitate the evaluation of
of the disc (to get a good stereoscopic view) in cases of possible open angle glaucoma i.e. it is useful to dilate these patients
what action should you take with someone who has a very narrow (potentially occludable) angle
refer anyways as they’re at a high risk of attack of ACG at any time, so not a good idea to dilate
what must you do for a px who has a suspect retinal detachment or wet AMD and you cannot obtain a sufficient view
must either dilate, or refer in worst case scenario or if they have a small AC angle
list 5 methods of assessing the risk of angle closure
- van herick
- flashlight test
- smith’s lit-length method
- methods using pachymeters
- gonioscopy
what grade in van herick is regarded as high risk of angle closure
grade 1
what is the gold standard method of assessing the risk of angle closure
gonioscopy
how is gonioscopy carried out, and by who
required local anaesthetic, a mirrored lens is put into cornea to see directly the anterior chamber angle
used by ophthalmologists and trained optometrists
what 5 things can you say/do to advise a patient regarding mydriasis
- loss of acuity
- glare problems
- driving difficulties
- recognition of symptoms of an acute ACG attack
- give information sheet
what things can contribute to loss of acuity, caused by mydriasis
- spherical aberrations
- reduced depth of focus
- paralysis accommodation for near & also distance for hyperopes is more substantially blurred
what can you advise a patient to do with glare problems caused by mydriasis
- patient may benefit from wearing sunglasses
- patient may wish to bring sunglasses with them to the examination
what is the biggest problem a patient notice when their pupils are dilated and what symptoms does this cause
glare which can by uncomfortable and disabling
what advice should you give to a patient about driving after dilation
recommended not to drive for the rest of the day or until drops have worn off (tropicamide 6-8 hours) and give an information sheet
what type of mydriasis drug is tropicamide
anti-muscarinic
how does tropicamide cause mydriasis
by relaxing the sphincter muscle (parasympathetic nervous system) of the iris so that the dilator muscle can work unopposed and cyclopegia by relaxing the ciliary muscle
what is the unwanted side affect of tropicamide
loss of accommodation by relaxing the ciliary muscle which causes affects to vision
how long is the onset of action of tropicamide
within approx. 10-30 mins
how long is the maximum effect of tropicamide
within approx. 20-40 mins
how long does it take to get recovery back to normal with tropicamide
approx. 4-9 hours
with which drug can CNS effects occur
cyclopentolate (a family of tropicamide which is stronger)
what must you be careful of possible interactions with before using tropicamide on a patient
be careful of possible interactions with other anti-muscarinics which are used for other conditions
which type of mydriasis drug is phenylephrine
sympathomimetic
how does phenylephrine cause mydriasis
stimulating the dilator (sympathetic nervous system) muscle of the iris
what is not complete when using phenylephrine and why
mydriasis is not complete
as dilatator muscle is weaker than the sphincter muscle, so sphincter muscle can still cause pupil miosis
what is not abolished on a patient when using phenylephrine for mydriasis
light reflex is not abolished, so patient will still react a small amount to light
what can phenylephrine be used in combination with for patients who are difficult to dilate
tropicamide, for maximum mydriasis
how long is the onset of action of phenylephrine
approx. 10-30 mins
how long is the maximum effect of phenylephrine
within approx. 30-90 mins
how long does it take to get recovery back to normal with phenylephrine
approx. 5-12 hours
according to the manufacturers Chauvin pharmaceuticals, what are the 2 conditions that phenylephrine is contraindicated with
- vascular hypertension
- long-standing insulin-dependent diabetes
so don’t use with patients who have these conditions
how long does it take to get recovery back to normal with phenylephrine
approx. 5-12 hours
according to manufacturers Chauvin pharmaceuticals, what 3 conditions should phenylephrine be used in caution with
- any diabetic
- long standing bronchial asthma
- cerebral arteriosclerosis (risk of stroke)
so must ask patients if they have any of these conditions
what do cycloplegic drugs cause to the eye
produce cycloplegia by paralysis or partial paralysis of the ciliary muscle i.e. accommodation is disabled
why may cycloplegic drugs be used in practice
if there are indications of fluctuating or excessive accommodation during refraction
which 2 group of patients are cyclopegic drugs mainly used on and why
- children, when their accommodation is unstable, making retinoscopy and subjective refraction unreliable
- young latent hypermetropia, as they find it hard to relax their accommodation
compared to which cycloplegic drug is cyclopentolate more effective at relaxing accommodation in young people than
tropicamide (used on adults with less accommodation)
although tropicamide is a cycloplegic drug, what is its main use for
dilating the pupil
which type of cycloplegic/mydriatic drug is cyclopentolate
anti muscarinic drug
how does cyclopentolate cause cycloplegia and mydriasis
causes cycloplegia by relaxing the ciliary muscle
causes mydriasis by relaxing the sphincter muscle of the iris
what is cyclopentolate more widely used for
cycloplegia and not mydriasis
how long is the onset of action for cyclopentolate
approx. 10-30 mins
how long is the maximum effect of cyclopentolate
within approx. 20-60 minutes
how long does it take to get recovery back to normal with cyclopentolate
within 24 hours (lasts longer than tropicamide)
which doses are cyclopentolate available in
minims of 0.5% and 1%
when will you tend to use 1% cyclopentolate and why
in children under 12 as they have a lot of accommodation to disable
when will you tend to use 0.5% cyclopentolate
in children aged 12 or over
with which drug will you be more likely to get a CNS effect with, e.g. tachycardia and why
cyclopentolate, because anti-muscarinic systemic effects can exasperate that problem
what do all mydriatics and cycloplegics bind with within the eye
with melanin on the iris and is slowly released my the melanin
what does instilling mydriatics and cyclopegics into dark irides lead to
slower onset of action of the drug (as the drug binds to melanin and takes longer to get to & take affect)
what does instilling mydriatics and cyclopegics into light irides lead to
longer duration of action i.e. lasts longer
what are local anaesthetics used in the eye for
to anaesthetise the cornea and conjunctiva
list the 3 ester types of ocular local anaesthetics and the dosage that they’re available in
- tetracaine (amethocaine) hydrochloride 0.5%
- oxybuprocaine hydrochloride (benoxinate) 0.4%
- proxymetacaine hydrochloride 0.5%
name a amid type of ocular local anaesthetic and the dosage it is available in
lidocaine 4%
what is the difference between an ester type and an amide type of ocular local anaesthetic
the chemical composition
when will you decide to use an amide type of ocular local anaesthetic over an ester type
in case of previous toxic/allergic reaction to ester anaesthetic
when will you decide to use an amide type of ocular local anaesthetic over an ester type
in case of previous toxic/allergic reaction to ester anaesthetic
give an example of when you will need to use and ocular local anaesthetic in practice
IOP measurement using goldmann tonometry
how long will it take to achieve complete anaesthesia with a ocular local anaesthetic
within 1 minute
what sensation do you get on instillation of a ocular local anaesthetic
stinging
which ocular local anaesthetic causes the most comfort on instillation
proxymetacaine hydrochloride 0.5%
what is the time for recovery from a ocular local anaesthetic and what is stated by the college of optometrists
very variable
college of optometrists advise 25 minutes in their information sheet for drops to wear off
what must you worn a px NOT to do when having a ocular local anaesthetic and why
not to rub their eyes during this time as can lose epithelial cells and cause damage to the cornea
what type of reaction may a ocular local anaesthetic cause, and what must you do do check for this
may cause toxic reaction, check for staining before leaving
what is the effect of prior instillation of a ocular local anaesthetic
corneal penetration of any other drug is increased
how is corneal penetration of any other drug increased when a ocular local anaesthetic is instilled before
as a ocular local anaesthetic reduces corneal integrity, so can penetrate quite a lot quicker
which drugs are used after instillation of ocular local anaesthetic and why
tropicamide or phenylephrine to dilate the pupil, because this gives a quicker response and can lead to a bigger pupil
list 3 things that flourescein is used in
- contact applanation tonometry - goldmann
- contact lens fitting
- assessing corneal damage
what were flourets licensed as in the UK
medicine
what dosage of minims is flurescein available in, and list some disadvantages to them for optometric practice
1% minims
expensive and availability problems
what is fluorescein now available in, after flourets were discontinued by bausch and lomb
paper strip form
what is the paper strip form of flourescein now classed as
medical device (instead of medicine)
what is a minim and why are they used in optometric practice
minim is a single dose container
used because they do not contain preservatives which some patients can be allergic to
minims should only be used once and then discarded in the yellow clinical waste bin
which waste bin should a single dose minim be discarded in
yellow clinical waste bin
list 5 things that can be discarded in a general waste bin in optometric practice
- used tissues
- packaging from drugs
- used and empty saline bottles
- used contact lenses
- used flourets
list 4 things that should be discarded in a yellow lid clinical waste bin in optometric practice
- used anaesthetic drugs
- used mydriatic and cyclopegic drugs
- used disposable tonometer heads
- used flourets
how are items disposed in a yellow lid clinical waste bin disposed of
by incineration (burning at high temperature)
what should be discarded in a clinical waste bin with a purple lid
used antibiotic drugs e.g. chloramphenicol
list the steps of how you will instil a drug into a patient’s eye
- Decide on appropriate drug and concentration.
- Check name and expiry date on the single dose container.
- Position the patient with head tilted backwards and restrained by the headrest.
- Instruct the patient to look up and nasally
- Hold the container vertically with the nozzle oblique to the surface of the conjunctiva. Steady the hand holding the container by resting it against the patient’s face.
- Gently pull lower eyelid down and away from the eye (? using a tissue) and squeeze one drop of the drug into the temporal side of the conjunctival sac. If more than one drop is required, leave a gap of several minutes before inserting a second drop. The contact time of the drug can be increased by obstructing the puncta by applying pressure at the inner canthus.
list 3 uses of topical anaesthetic in practice
- applanation tonometry
- scleral contact lens fitting
- to facilitate removal of foreign bodies
