ocular diagnostic drugs Flashcards
when do we use mydriatics?
*More thorough examination of peripheral crystalline lens, vitreous, fundus
*Facilitates a stereo fundus examination (volk)
*For treatment in Uveitis (stops iris sticking to lens and causing increase in IOP)
*If px is at risk of retinal detachment (high myopia more than 5D, family history, trauma)
*Symptoms: unexplained visual loss/visual field loss, visual disturbance, floaters, flashes, veils, shadows
*Screening for diabetes, high myopia, prior to ocular surgery
*Inadequate fundus view (lens/media opacities, miotic pupil less than 2mm in diameter)
what should you do prior to installation of a mydriatic?
*Good reason to use drug
*Explain procedure (tell them it will sting)
*Px consent (issue written information)
*Advise of after effects: glare, loss of stereo vision, no driving or operating machinery
*Minimise risk of adverse reaction
*Check for contraindications
how should you install the mydriatic?
*Write down DRUG, STRENGH, DOSAGE, EXPIRARY DATE, BATCH NUMBER and TIME of instillation
*Ask px to look up and pull down the lower eyelid.
*Instil one drop into lower conjunctival sac
*Occlude puncta-avoids drug draining int nasolacrimal duct. This reduces effectiveness of drug and increases likelihood of causing systemic signs and symptoms
what are the general contraindications of mydriatics?
Known hypersensitivity to the drug
*Iris clip IOL’s
*Narrow VH angle
*Patients with symptoms of sub-acute or chronic closed angle glaucoma (CAG)
*Patients diagnosed with CAG
*Px using pilocarpine for glaucoma treatment (constricts pupil which opens up drainage channels)
what are the sings and symptoms of closed angle glaucoma after using tropicamide?
blurred vision
haloes
headache
pain
vomiting/nausea
photophobia
closed angle
fixed mid-dilated pupil
cloudy cornea
conjunctival hypereamia
sudden increase in IOP (more than 40mmHg)
how can we minimise risk of CAG?
IOP-take pre and post dilation
check anterior angles: van herricks
existing symptoms: ask if already has sings of angle closure like haloes around lights, painful eye
use of a miotic drug (not done in optometric practice)
how do you do van herick’s technique
what do the rations mean
1 mm beam at 60 degrees
low mag (10x)
compare width of anterior chamber to width of corneal section
gap:cornea
1:1 grade 4
0.5:1 grade 3
0.25:1 grade 2
<0.25:1 grade 1
what are the types of mydriatics?
how do they work?
name them
Muscarinic antagonists/antimuscarinic/anticholinergic
Blocks Acetylcholine effect on muscarinic receptors
1.Tropicamide: most used
2.Cyclopentolate: rarely used as a mydriatic
3.Atropine: only available to independent prescribers. Unlikely to be used as mydriatic due to toxicity.
Sympathomimetic/alpha antagonist
Enhances noradrenaline effects on alpha 1 adrenoreceptors
- Phenylephrine: used more in USA
what does the sympathetic system do?
what does the parasympathetic system do?
what transmitter, receptor, and muscle is part of parasympathetic system?
what transmitter, receptor, and muscle is part of sympathetic system?
fight or flight
inhibit body overworking
transmitter: acetylcholine
receptor: muscarinic
muscle: ciliary and sphincter
transmitter: noradrenaline
receptor: alpha
muscle: dilator
how does anti-muscarinic action cause dilation?
parasympathetic stimulation causes contraction of the iris sphincter and constriction of the pupil.
paralysis of the parasympathetic system inhibits the action of Ach liberated at the postganglionic nerves. this produces mydriasis, cycloplegia, reduced tear secretion.
how does sympathomimetic action cause dilation?
*Noradrenaline is the transmitter in sympathetic system
*Mainly alpha 1 receptors in dilator pupillae muscle
*Alpha 1 is excitatory and alpha 2 is inhibitory
*Beta 1 is excitatory and beta 2 is inhibitory
*Phenylephrine is a selective alpha 1 adrenergic receptor activator acting on the iris dilator muscle
TROPICAMIDE
how long does mydriasis take?
how long does recovery take?
is light reflex absent?
what else does it cause?
how may contraindications are there?
15 mins
8-9 hours
yes
mild cycloplegia effect, may cause rise in IOP
few
PHENYLEPHERINE
how long does mydriasis take?
how long does recovery take?
is light reflex absent?
does it effect accommodation and IOP?
how many contraindications are there?
30 mins
12-24 hours
no its retained
accommodation is retained, less likely to cause rise in IOP as sector mydriasis
numerous
what is the medical legislation for tropicamide?
what concentrations is it available in and how should it be stored?
who is 1% used in?
POM
single use minims kept at room temp
0.5%
1.0%
multi-dose containers refrigerated and protect from light
0.5%
1.0%
in people with darker irides or kids as increased cycloplegia effect
who should you avoid using tropicamide in?
*Avoid use in pregnancy but better option than phenylephrine
*Not to be used in breast-feeding women
what are the ocular side effects of tropicamide?
what are the general side effects on the body?
transient stinging, transient blurring, photophobia, raised IOP
prolonged administration: irritation, hyperaemia, oedema, conjunctivitis
dry mouth (reported in blue eyed blond hair children)
what is the medical legislation of phenylephrine?
what concentrations are available? how is it stored?
what else is this drug used for?
P
stored at 25 degrees, protect from light
2.5%
10% (contraindicated in children and elderly)
Is used as a test to distinguish between scleritis or episcleritis
what are the contraindications for using phenylephrine?
anti-hypertensives, tachycardia, cardiovascular problems medication
depression medication (MOIs, tricyclic antidepressants)
thyrotoxicosis (excess thyroid hormone)
insulin dependant diabetes
asthma
pregnancy/lactation (can cause fatal hypoxia)
use of pilocarpine (pupil block in older px and accommodative spasm in your px)
what are the ocular side effects of phenylephrine?
what are the general side effects?
transient stinging
transient blurring
photophobia
lid retraction
conjunctival allergic reaction
punctate keratitis
palpitations, tachycardia, cardiac arrhythmias, hypertension, headaches
what synergists combinations are available for mydriatics?
why may these be used?
*Can have tropicamide 0.5% and phenylephrine 2.5%
*Allows lower concentrations of antimuscarinic to be used so less cyclo effect
what is the medical legislation of mydriasert?
what is this?
when is it used and for how long?
*POM
*Insoluble ophthalmic insert
*Contains phenylephrine and tropicamide
*Gradual release of drug
*Used pre-operatively and diagnostically
*In adults its inserted up to max 2 hours before procedure.
*It’s removed within 30 minutes of mydriasis and within 2 hours of application.
what other mydriatic drugs are available?
cyclopentolate (anti-muscarnic)
homatropine (anti-muscarinic)
HOMATROPINE
how long does mydriasis take?
how long does recovery take?
are light and accommodative reflex absent?
maximal 30-40 mins
3 days
yes
what can phenylephrine cause?
is phenylephrine less effective in pigmented eyes?
widening if palpebral aperture
blanching of conjunctiva (vasoconstriction of conjunctival blood vessels)
yes
which curve shows decline in accommodation with age?
Duane’s curve
what are the optometric uses of cycloplegics?
*Assessment of refractive error.
*If concerned about latent hyperopia: accommodative muscles are used to increase the eyes focusing power.
*Penalisation instead of occlusion of one eye
*Helps Adaptation to spectacles (rare)
what are the ophthalmic uses of cycloplegics?
*Anterior uveitis-dilating pupil and alleviating ciliary spasm
*Corneal abrasion- alleviate ciliary spasm
what are the optometric indications for using cycloplegics from the history and symptoms?
Symptoms: asthenopia, reading difficulties
History of manifest deviation
Family history of refractive error at an early age or manifest deviations
what are the optometric indications for using cycloplegics from the clinical tests?
Binocular vision anomaly: manifest eso deviation, sometimes latent deviation
Fluctuating ret: large difference between subjective and objective. Poor fixation.
Accommodative anomalies
Visual acuity reduced
what are the cycloplegic effects?
1.Mydriasis: iris is located anteriorly to ciliary body. This is an unnecessary side effect.
2.Cycloplegia: paralysis of ciliary muscle results in loss of accommodation. Due to ciliary muscle paralysis, lens can’t change shape to focus on near objects.
3.Reduced tear secretion. Px may complain of dry eye after instillation.
what do anti-muscarinic agents effect?
- Lacrimal gland
- Iris sphincter muscle
- Ciliary body
what advice is given to parents before instilling cycloplegics?
*Explain need to use it. Consequences of not using it.
*Onset
*Duration
*Expected side effects (temporary blurred vision)
*caution
what advice is given to child before instilling cycloplegics?
*explain they might feel a drop on the eye
*RCO advise 1 drop of proxymetacaine first.
what happens if consent is denied for instilling cycloplegics?
*Explain disadvantages and advantages to parent
*Note refusal on record. Get Px to sign this.
*Record all discussion on notes
*If concerns for child are greater, refer to GP.
how should we checking for cycloplegia?
how should you instill drops in kids?
measure accommodation
check ret reflex
*Lying down might help
*Sometimes drop onto eyelashes might help.
mydriasis does not indicate…
cycloplegia
how is cycloplegia retinoscopy performed?
*Sit younger child on parent knee
*Ask px to fixate upon light.
*Ensure ret is conducted upon axis
*No need to fog other eye
*Can use a lens rack
*Observe central movement 3-4 mm. ignore movement in the periphery.
what cycloplegics drugs are available?
atropine
cyclopentolate
homatropine
tropicamide
what is atropine sulphate?
what is the medical legislation?
*First muscarinic antagonist used in medicine
*Naturally occurring compound: “belladonna” deadly nightshade.
*Toxic agent
POM
what preparations can you get for atropine sulphate?
*Eye drops (non-proprietary)
-0.5% atropine sulphate
-1.0% atropine sulphate
*Eye ointment
-1% atropine sulphate (non-proprietary)
*Minims
-1% atropine sulphate (Bausch&Lomb)
how should atropine sulphate be stored?
how old does a kid have to be to use it?
what is the dose?
store below 25 degrees (room temp) and protect from light
older than 3 months
Eye drops
-1 drop (1%) 2x a day for 1-3 days before refraction
Ointment
-2x a day for 1-3 days before refraction
-preferrable to use ointment as less systemic toxic effects due to prolonged contact with the eye
*Ask px to return any unused ointment on the day of refraction given its toxic side effects
distilling 1 drop of 1% atropine
how long does mydriasis take to happen?
how long does recovery take?
how long does cycloplegia take to start?
how long does recovery take?
maximal in 3-40 mins
recovery in 3-7 days
maximal in 1-3 hours
recovery in 3-7 days
what is Tonus allowance?
when does spherical power need to be adjusted?
*Ciliary muscle has dependant and independent tone
*Allowance needs to be made for dependant tone
Spherical power only needs to be adjusted in less positive direction
*-1.00DS for low myopes and all hyperopes
*0.00DS for moderate and high myopes
what are the contraindications for atropine?
what are the cautions?
*Known allergy to atropine or component of the preparation
*Narrow angles
*Children
*Children younger than 3 months
*Elderly or debilitated
*Downs syndrome
*Children with brain damage (hypersensitivity to drug)
*Soft contact lens wearers: multi-dose containers contain benzalkonium chloride.
*Intermittent manifest deviations
*Pregnancy and lactation
*Interaction with drug/ointment
what are the ocular side effects of atropine?
what are the general side effects of using atropine?
*Transient stinging
*Blurring
*Photophobia
*Raised IOP
*Repeated use: hyperaemia, oedema, itching, irritation, follicular conjunctivitis
*Dry mouth and skin
*Flushing, increased body temp
*Cycloplegia
*CNS effects-ataxia, hallucinations, confusion, difficulty in speaking
*Tachycardia
*Death from respiratory depression (more likely in children)
what are the additional uses of atropine?
*Used to treat amblyopia
*Instilled into the better eye
*Prevents accommodation
*Used when child doesn’t tolerate patching
Excellent results
what is cyclopentolate hydrochloride?
what is the medical legislation?
what formulations can you get and how should they be stored?
most used cycloplegic
synthetic drug
stings
not commonly used as a mydriatic
POM
Mydrilate: eye drops
-mydrilaite (intrapharm)
-0.5% cyclopentolate HCL
-1.0% cyclopentolate HCL
stored between 2-8 degrees. kept in fridge.
Minims
-0.5% cyclopentolate HCL
-1.0% cyclopentolate HCL
-stored below 25 degrees, room temp, protect from light
when should the different concentrations of cyclopentolate be used?
is tonus allowance required for cyclopentolate?
*Up till the age of 12 years: use 1% cyclopentolate
*If iris pigmentation is light, 0.5% may be suitable
*No tonus allowance made
*Always give full Rx found expect from:
-hyperopia with exo deviation
-myopia with an eso deviation
when does cycloplegia commence after instillation?
when does recovery happen?
30-50 minutes
4-12 hours
what are the cautions for using cyclopentolate?
*Young children
*Debilitated patients
*Elderly
*Avoid over dosage in darkly [pigmented eyes
*May help to compress lacrimal sac 2-3 mins after instillation of the drop to makes sure maximal amount of drug is available in the eye
*Pregnancy and lactation
*Hallucinations and CNS effects reported with high concentration of the drug
what are the ocular side effects of cyclopentolate?
what are the general side effects?
stinging
blurring
photophobia
raised IOP
conjunctival hyperaemia and oedema
after prolonged administration: irritation, hyperaemia, oedema, conjunctivitis
CNS effects
dry mouth
flushing
tachycardia
urinary symptoms
GI symptoms
what are the additional uses of cyclopentolate?
Adaption to spectacles
*Children almost always adapt well to hyperopic
prescriptions
*Use 1% cyclopentolate daily for 2 weeks
*Accommodation is abolished.
*Clear vison is only obtained with spectacle wear
*Child usually then accepts spectacle wear
Mydriasis
* Commences after 10 minutes
* Maximal in 30-60 mins
* duration is approx. 24 hours
for anterior and posterior uveitis and posterior synechiae breakdown
* 1 to 2 drops of 1% cyclopentolate are instilled every 6-8 hours
For alleviation of ciliary spasm
* 1 drop of 1% cyclopentolate 2-3 times per day.
what is the medical legislation of homatropine hydrobromide?
what is the concentration?
how is it stored?
what is the use?
how long does mydriasis take?
how long does recovery take?
POM
1% multi dose containers
store below 25 degrees (room temp) and protect from light
*Dilating the pupil in patients with anterior uveitis
*Alleviation of ciliary spasm following a corneal abrasion
maximal in 30-40 minutes
Recovery takes 24-48 hours
what does degree of cycloplegia depend on when using tropicamide?
how long does mydriasis and recovery take?
how long does cycloplegia and recovery take?
*AGE
-only indicated for cycloplegic refraction in older patients’ late teens or older rather than children.
-only 1% strength is suitable
*IRIS PIGMENTATION
-degree of cycloplegia is dependent on pigmentation
Mydriasis after approx. 15 mins
Recovery: 8-9 hours
Cycloplegia maximal 30 mins
Recovery: 6 hours
what do anaesthetics do?
what is their medical legislation?
what are the indications of use?
what can anaesthetic use lead to?
they reversibly block transmission in sensory nerves
POM
*Impressions for CL fittings
*Contact tonometry
*Removal of foreign body
*Gonioscopy: interior, anterior eye
*Lacrimal procedures (insertion of punctual plugs)
*Never to be used for relief of symptoms as healing is delayed in an already compromised eye. Can be addicting. Can lead to keratitis and enucleating.
what are the advantages of using anaesthetics?
what are the disadvantages of using anaesthetics?
allows certain procedures to be conducted
make the px more comfortable
makes procedures easier for practitioner
sting due to pH
delay healing (reduced production of collagen)
eye is more susceptible to damage
what is the mode of action of anaesthetics?
*Sensory information passes along the nerve fibres via electrical impulses (known as action potentials)
*A nerve has negative charge at rest. Action potential is generated by influx of sodium ions into the nerve
*Results in depolarisation (positive charge)
*Efflux of potassium ions which returns the nerve back to its resting potential (repolarisation)
*Action potential passes along the nerve
*There are successive depolarisations and repolarisations of adjacent area
*Topical anaesthetics reversibly block nerve conduction by blocking sodium channels so action potential can’t be generated.
what are the 2 chemical structures of anaesthetics?
what anaesthetics are under them?
Ester link
hydrolysed by cholinesterase
short duration-ester ki image broken more common
1.oxybuprocaine
2.tetracaine
3.proxymetacaine
amide link
Resistant to hydrolysation
Longer duration
1.lidocaine
what are the precautions for using anaesthetics?
*Permeability of epithelial cells increases after instillation of anaesthetic, so it enhances effect of other drugs
*Healing of epithelial cells is reduced by use of topical anaesthetics
*Open to abuse by healthcare practitioners
*Need to be caution in using them on young children
what are the side effects of all anaesthetics?
*Transient stinging
*Transient blurring
*Conjunctival hyperaemia
*Mild superficial epithelial damage. Not uncommon, especially with tetracaine. It represents local toxicity.
*Punctate keratitis
*Systemic reactions are rare due to small quantities of drug involved.
*Hypersensitivity reactions (less likely with lidocaine due to amide link) can range from mild transient blepharoconjunctivitis to diffuse necrotising epithelial keratitis
*Necrotising keratitis incidence: 1 in a 1000 with ester drugs
*Repeated use leads to epithelial toxicity. This can lead to serious keratopathy. Can involve epithelial loss, stromal oedema, corneal infiltrates, anterior chamber reaction.
what is the drug name, onset, and duration for anaesthetics?
amethocaine/tetracaine 1 min. 20 mins
benoxinate/oxybuprocaine 1 min 15 mins
proxymetacaine/proparacaine 1 min 15 mins
lignocaine/lidocaine 1 min. 30 mins
TETRACAINE HYDROCHLORIDE
benefits?
bad things?
preparations available?
stored how?
contraindications/cautions?
Provides deepest anaesthesia (good for foreign body removal after 1 drop). sensitivity is rare.
stings the most. associated with punctate staining. most potent.
0.5 and 1.0 % minims
Store below 25 degrees
Protect from light (chemical structures hydrolysed by light so drug will be damaged)
- Sulphonamides (group of drugs)
- Premature babies
- Know allergy
- Patients who are pregnant or breast feeding.
OXYBUPROCAINE HYDROCHLORIDE
benefits?
bad things?
preparations available?
how is it used in ophthalmology?
stored how?
contraindications/cautions?
most widely used. sensitivity reaction is rare. less stinging.
Has bactericidal properties. Can be a problem if you complete goldman’s prior to corneal culture being taken in hospital.
0.4% minims
Used in ophthalmology
Three drops instilled over 5 minutes. Allows foreign body to be removed.
Corneal sensation recovers approx. after 1 hour.
Store below 25 degrees
Protect from light
*Known allergy
*Of other eyedrops containing chlorhexidine acetate as a preservative are being used
*Pregnancy/breast-feeding
*Premature babies
PROXYMETACIANE HYDROCHLORIDE
benefits?
bad things?
preparations available?
stored how?
what procedure can it be used for?
contraindications/cautions?
stings the least. minimal punctate staining.
Least antibacterial properties (useful when taking conjunctival swabs). Sensitivity is rare.
Very potent
0.5% minims
Store at 2-8 degrees so kept in dedicated refrigerator.
Can be used in cataract extraction.
1 drop ever 5-7 minutes.
5-7 drops in total
- Known allergy
- Overactive thyroid
- Heart disease
- Premature babies
- Pregnancy/
breast feeding
LIDOCAINE HYDROCHOLRIDE
benefits?
preparations available?
stored how?
contraindications/cautions?
stings less. amide link so used in those sensitive to esters. longer duration.
4% minims combined with 0.25% fluorescein
Store below 25 degrees
Protect from light
*Pregnancy/
breast feeding
*Premature babies
what are the most common diagnostic stains?
uses?
disadvantages?
fluorescein sodium
uses: tonometry, corneal abrasions, contact lens fittings
disadvantages: pseudomonas aeruginosa in multi-dose bottles
rose bengal
uses: staining of dead and revitalised cells in cornea and conjunctiva to aid dry eye diagnosis.
disadvantages: irritates dry eyes on instillation and stings. can also stain healthy cells.
lissamine green
uses: stains lipid-like structures, dead epithelial cells, membranes of damaged cells, mucus. does not stain healthy cells.
what is the medical legislation of fluorescein sodium?
what is it?
in what form is it used?
what is a disadvantage?
how does it work?
what filter can be used to improve contrast?
P
Orange-red dye fluoresces in high dilution
Used topically. Can be injected for fluorescein angiography.
If there is epithelial damage, fluorescein can gain access to deeper layers
Light 485 to 500 nm is absorbed maximally. This absorbed energy excites fluorescein molecules.
wratten 12
what can fluorescein be used for?
what are the contra-indications?
what are the problems with multi-dose bottles?
*Assessment of corneal integrity (from trauma, disease, contact lens after-care)
*Rigid contact lens fitting
*Contact tonometry
*TBUT
*Lacrimal patency (if drainage system is open)
*Lacrimal drainage
- Know sensitivity
- Absorbed by soft contact lenses
- Contamination problem in hospital in 1950’s
- Fluorescein is used on damaged corneas
- Pseudomonas has affinity for fluorescein.
- Corneal perforation within 48 hours.
where in the eye should you install fluorescein?
what formulations is it available in?
how should it be stored?
lower conjunctival fornix due to bells palsy
minims: 1%, 2%
fluorescein impregnated strips approx 1mg
room temp (below 25 degrees)
what is rose bengal stain a derivative of?
what does it stain?
why is it not used as much?
what conditions is it useful in?
what formulation is it available as?
*Derivative of fluorescein
*Stains devitalised epithelial cells of cornea and conjunctiva. Also stains mucous strands.
*Sting on insertion, especially in dry eye conditions. Can put anaesthetic in before.
*May cause punctate staining.
*Has toxic effect on human corneal epithelial cells enhanced by light exposure
keratoconjunctivitis sicca
dendritic keratitis
neuroparalyctic keratitis
exophthalmos
pressure ares due to contact lens wear
Available in:
1 % minims- not commercially available
ophthalmic strips 1.3 mg
what formulation is lissamine green available as?
why is it better than rose bengal?
how does it work?
how should you observe staining?
opthalmic 1.5 mg strips
Some evidence too suggest early signs of dry eye disease are more visible with lissamine green compared to fluorescein
*Easier to view against light irides
*Sting less and less toxic than rose Bengal
*Binds to nuclei of severely damaged cells like rose Bengal
*Observe 1-4 minutes after instillation
*If you observe it too soon, staining pattern won’t have developed. If you observe it too late, staining pattern may fade.
*Begin with low illumination. High illumination will bleach out the appearance of some staining
*Can use red filter to enhance view (wratten 25)
what is the medical legislation of lissamine green?
CE market product for use as a diagnostic agent
what other stains are available and what do they stain?
alcian blue: stains mucus
trypan blue: stains mucus and dead cells which have undergone structural changes
bromothymol blue: stains degenerate and dead cells, mucus. used to investigate damage by chemical agents.
methylene blue: bacterial stain, also stains nerve tissue
tetrazolium and lodonitrotetrazolium: tetrazolium stains degenerate cells. staining of tumours and assessing corneal grafts.
