Cyloplegia and mydriasis Flashcards
what is cycloplegia
the paralysis of the cillary muscle resulting in a loss of accomoodattion
what is the cillary body innervated by
cillary body is innervated by the parasympathetic nervous system
cycloplegia agents stop this innervation by competing with the acetylcholine receptor sites on the post synaptic membrane of the cillary muscle
how is accomodation inhibited by cloplegics
although the drugs occupy the post synaptic receptor sites they don’t initiate the depolarisation of the neurone , by occupying these sites each is rendered ineffective temporarily
the nerve impulse which was started in the endanger Westphalia nuclei travelled via the cranial nerves does not activate the cillary muscle
this results in the temporal paralysis of accomodation
what drug types are clycloplegics
All cycloplegics are anti-muscarinic,
anticholinergics,
cholinergic antagonists,
muscarinic antagonists,
muscarinic inhibitors,
parasympatholytics.
Note these synonyms!
how should atropine 1% be used
Typically single-dose preparations (Minims) but can be as multi-use bottle (with preservative). Prescription Only Medicine (POM)
3 months to 17 years
Cautions:
Pigmented irides.
Narrow angles.
Neonates.
what interactions should you be aware of when using atropine
Typically other drugs which have antimuscarinic effects but also levodopa (used in Parkinson’s disease) as cyclopentolate can reduce the absorption of levodopa.
Phenylephrine; atropine increases the risk of severe hypertension.
what are the side effects of atropine
Photophobia, stinging.
confusion
constipation
dizziness
drowsiness
dry mouth
dyspepsia
flushing
headache
nausea
palpitations
skin reactions
tachycardia
urinary disorders
vision disorders
vomiting
how should cycloplentate 0.5% and 1% be used
flushing
headache
nausea
palpitations
skin reactions
tachycardia
urinary disorders
vision disorders
vomiting
what drug interactions should you be aware of with cyclopentalate
flushing
headache
nausea
palpitations
skin reactions
tachycardia
urinary disorders
vision disorders
vomiting
what are the side effects of cyclopentalate
Abdominal distension
arrhythmias
behaviour abnormal
cardio-respiratory distress
conjunctivitis (on prolonged administration)
constipation
dry mouth
eye oedema (on prolonged administration)
flushing
gastrointestinal disorders
hyperaemia (on prolonged administration
palpitations
psychotic disorder
staggering
urinary disorders
vomiting
how should tropicimacide be used 0.5% and 1%
As Minims or multi-use (Mydriacyl).
For cycloplegia in older children or teens one drop 1% followed by another drop five minutes later. POM
Cautions.
Pigmented irides. Narrow angles. Neonates.
what drug interactions should you be careful of with tropiciamidie
Typically other drugs which have antimuscarinic effects but also levodopa (used in Parkinson’s disease) as cyclopentolate can reduce the absorption of levodopa.
Clozapine; risk of developing intestinal obstruction. Manufacturer advises caution.
what are the side effects of tropiciamide
Eye erythema
eye irritation (on prolonged administration)
eye pain; headache
hypotension
nausea
syncope
vision blurred
(From BNFC 12-9-2022)
what are the clinical uses of tropcimide
Paediatric refraction
Amblyopia therapy
Uveitis
Alleviation of ciliary spasm
what is paediatric refraction necessary for
Essential for any practitioner to know the true refractive state in all presentations of paediatric strabismus, particularly esotropia. (Fotedar et al 2007)
The gold standard was atropine (and still gives the greatest depth of cycloplegia) but today Cyclopentolate 1% is the preferred choice. (College of Optometrists 2019, Farhood 2012)
what is the ideal drug for refraction
fast-acting,
give adequate cycloplegia
last long enough for the refraction to take place
have no local or systemic side-effects.
what is cycloplentalate best for
refraction
Cyclopentolate does well on all of these although there are potential local and systemic side effects.
Local: ocular stinging, allergy.
Systemic: CNS disturbances such as ataxia, incoherent speech, restlessness, hallucinations, hyperactivity, and disorientation. Children should be monitored for 45 minutes post-instillation.
how is atropin used in optical penalisation
In 2002, the Paediatric Eye Disease Investigator Group (PEDIG) published the results of their multi-centre randomised clinical trial involving 419 children with amblyopia.
They were assigned to either a patching group or atropine group.
Visual acuity in each eye was measured after 6 months and compared and they found no significant difference between the treatment modalities. (PEDIG 2002)
why is atropine best used in optical penalisation
Atropine 1% is placed into the better seeing eye, thereby preventing that eye from having a clear stimulus at near and forcing the amblyopic eye to read.
It is also possible to reduce any hyperopic correction in the better seeing eye to also cause blur at distance.
1% atropine was instilled everyday and the children were provided with sunglasses and advised to wear a hat.
how often should atropine be administered
Currently, weekend atropine or twice-weekly instillation of atropine 1% is indicated. (Taylor and Bryant 2012)
Close monitoring of adherence is essential and can be easily checked by observing pupil dilation (better by doing dynamic ret!).
If the vision does not respond then conventional patching should be considered.
The long-lasting action of atropine is the main reason why it is preferred to Cyclopentolate for amblyopia therapy.
what is uvetis
In particular anterior uveitis (iritis). Uveitis is the inflammation of the uveal tract and anterior uveitis is the inflammation of the iris and ciliary body.
The acute type typically presents in young adults as a uniocular painful red eye which has affected the vision.
The patient is photophobic and may have a history of systemic inflammatory disease, eg rheumatoid arthritis.
what would you see on a slit lamp with uveitis
marked circum-limbal injection
cells in the anterior chamber
flare
keratic precipitates
possibly hypopyon
the pupil may be misshapen due to posterior synechiae.
what is the management of a patient with uveitis
The patient will hate you looking with the slit lamp!
The chronic type may be much more subtle in it’s presentation. Both types (acute and chronic) require a doctors opinion.
Cyclopentolate 1% is given to break/prevent the synechiae and to reduce the pain due to the ciliary body/iris being inflamed by preventing the movement associated with accommodation.
Steroids are also prescribed by the doctor to reduce the inflammation.
how is a cillary spasm alleviated
In some cases of corneal abrasion, the ciliary muscle can go into a spasm which is extremely uncomfortable.
Cyclopentolate 1% can be administered to alleviate this spasm through cycloplegia.
what is mydriasis
All anti-muscarinics will cause pupil dilation (mydriasis) as the sphincter papillae of the iris receives parasympathetic innervation.
Therefore, stopping this muscle from working leaves the dilator papillae to exert it’s affect without competition and the pupil will dilate.
Therefore, stopping this muscle from working leaves the dilator papillae to exert it’s affect without competition and the pupil will dilate.
If one stimulates the dilator papillae using an adrenergic agonist (sympathomimetic) then this will result in mydriasis.
what is a combination approach and how is it used
Often, a combination approach is used which creates mydriaisis using one drug from each class. Eg phenylephrine 2.5% and tropicamime 1%.
This is particularly seen when checking infants for signs of retinopathy of prematurity and in adults when the peripheral retina needs to be seen in suspected retinal detachment.
NOT atropine with phenylephrine!!!
how is atropine 1% used
Rarely used as a mydriatic due to long time of onset, long lasting effect and potential toxicity.
Only used if other drops ineffective or allergy. Eg heavily pigmented irides. POM
how is clyclopnetalte 0.5% used
More frequent use than atropine but not drug of choice as cycloplegic effect too great.
Again used in case of ineffective dilation with Tropicamide or allergy. POM
how is tropicimide 0.5% used
sufficient to produce 6mm pupil diameter in young healthy adults (Siderov and Nurse, 2005)
Usually tolerated better than the above due to rapid onset and faster recovery and usually leaves some residual accommodation. POM
how is pheneleyrphyine 2.5% used
Available as Minim. Pharmacy medicine (P)
Cautions:
Asthma;
corneal epithelial damage
darkly pigmented iris is more resistant to pupillary dilatation and caution should be exercised to avoid overdosage
diabetes (avoid eye drops in long standing diabetes)
what should you be cautious of with phenelyerphine
mydriasis can precipitate acute angle-closure glaucoma in the very few children who are predisposed to the condition because of a shallow anterior chamber
neonates are at an increased risk of systemic toxicity (in neonates);
ocular hyperaemia
susceptibility to angle-closure glaucoma
what phenelyrphine interactions should you be careful of
BNFc cites 19 drugs with severe interactions, including with atropine. Please check the site for details.
Side effects:
Conjunctivitis allergic
eye discomfort
hypertension
myocardial infarction (usually after use of 10% strength in patients with pre-existing cardiovascular disease)
periorbital pallor
vision disorders
what are the risks of 0.5% tropicimide and 2.5% phenelyrphone
As stated, in many clinics 0.5% Tropicamide and 2.5% phenylephrine are used in all healthy adults.
It is important to take a careful medical history prior to instilling these drops.
Also, there is a risk of precipitating angle closure glaucoma in susceptible individuals and assessment of the potential to close should be carried out on all patients.
In particular, older, phakic female hypermetopes of East Asian descent are particularly at risk.
which patients should be dilated
The use of mydriasis is to aid the examination of the fundus, especially for indirect viewing techniques such as Volk lens examination with a slit lamp or headset mounted binocular indirect ophthalmoscopy.
It is particularly indicated when wishing to view the peripheral fundus, commonly needed to check for retinal tears following posterior vitreous detachment (PVD).
Ensuring adequate mydriasis is essential but using too much of any of the agents mentioned here increases the risk of systemic absorption and raises the possibility of systemic effects.
