1- Cycloplegia and Mydriasis Flashcards
What are the three drug classifications?
Pharmacy medication (P)
Prescription only medication (POM)
General sales list (GSL)
What are pharmacy medications
Definition: Medicines that do not require a prescription but must be sold under the supervision of a qualified pharmacist in a registered pharmacy.
Examples: Larger packs of painkillers, antihistamines, and certain nasal sprays or eye drops.
Key Points:
Not available in non-pharmacy retailers.
Pharmacist supervision ensures that the medication is appropriate for the buyer.
What are prescription only medications
Definition: Medicines that require a valid prescription from a healthcare professional (e.g., doctor, dentist, or nurse practitioner) before they can be dispensed.
Examples: Antibiotics, strong painkillers like morphine, and medications for chronic conditions like high blood pressure or diabetes.
Key Points:
Available only at pharmacies upon presentation of a prescription.
Used for conditions that require professional diagnosis and monitoring.
What are general sales list medications
Definition: Medicines that can be sold without a prescription and are available from general retailers, such as supermarkets or convenience stores.
Examples: Paracetamol (in limited quantities), ibuprofen, and some cough syrups.
Key Points:
Can be sold in outlets without a pharmacy.
Pack sizes and dosages are often limited to ensure safety.
Examples of POMs
(ACT)
Atropine
Cyclo
Tropicamide
What do atropine, cyclopentolate and tropic amide have in common
They are anti muscarinic and allow for mydriasis
What class is phenylephrine
P medicine
What does phenylephrine do
It’s sympathomimetic- gives mydriasis and has minimal affect on accommodation- just a mydriatic
Literature definition of cycloplegia
Millodot defines cycloplegia as the “paralysis of the ciliary muscle resulting in a loss of accommodation.” (Millidot, M. 2018)
What does AcH do
Its a neurotransmitter that initiates nerve conduction
What type of drug is needed
Need a drug that mimics AcH so that it binds at the receptor site on the post synaptic membrane but we don’t want to initiate nerve conduction
Post receptor sites are blocked with our drug and this gives temporary paralysis of accommodation
Which drug lasts the longest
Atropine
Which drug lasts the shortest
Tropicamide
What’s the ciliary body innervated by
The ciliary body is innervated by the parasympathetic nervous system.
Cycloplegic agents temporarily stop this innervation by competing with acetylcholine at the receptor sites on the post-synaptic membrane of the ciliary muscle.
Innervation
- Although the drugs occupy the post-synaptic receptor sites, they do not initiate depolarisation of the neuron.
- By occupying these sites, acetylcholine is rendered temporarily ineffective
- The nerve impulse, which was started in the Edinger-Westphal nucleus, travelled via the Third cranial nerve, does not activate the ciliary muscle.
- This results in the temporary paralysis of accommodation.
What are all cycloplegics
Anti- muscarinic
List of synonyms of anti muscarinic
acmmp
- anticholinergics,
- cholinergic antagonists,
- muscarinic antagonists,
- muscarinic inhibitors,
- parasympatholytics.
What are anticholinergics
drugs that interfere with the action of acetylcholine (ACh)
(ACh) is a key neurotransmitter in the nervous system.
Lysis means…
Break down
How is atropine prepared
Typically single-dose preparations (Minims) but can be as multi-use bottle (with preservative).
Atropine class and age appropriate
POM
3 months to 17 years
Cautions for atropine use
- Pigmented irides.
- Narrow angles- risk of angle occlusion
- Neonates
- Big amounts can cause death and illness
- Single dose have no preservatives
- Can cause allergy, hypersensitivity
Cons of atropine
- more expensive
- May need to instill more drugs if not absorbed
- Risk of systemic side effects with more doses
- Atropine comes from plant deadly night shade- can be toxic
Note for Atropine
- Close the angle due to the trabecular meshwork and allow the aqueous to drain- causes acute glaucoma if closed angle
- Dilation makes all iris tissue to be dragged back towards the angle- risk of angle occlusion
- Assess risk using Van Hericks
- If in doubt ask doctor or nurse praticiconer to view structures in the angle to decide if risk is too high
Atropine interactions
3- P O L
Phenylephrine- atropine + phenylephrine causes severe hypertention and serious cardiovascular problems
Other anti muscarninc drugs
Levodopa (atropine can redice the absorption of this Parkinsons medication)
Atropine side effects
- Photophobia, stinging- caused by mydriasis
- confusion
- constipation
- dizziness
- drowsiness
- dry mouth
- Dyspepsia- acid reflux
- If child swallows atropine must go to A and E
- As body weight affects how drug is metabolized
- Atropine can shut down the brain if drank
More atropine side effects
- flushing
- headache
- nausea
- palpitations
- skin reactions
- tachycardia
- urinary disorders
- vision disorders
- vomiting
- Instillation procedure must minimize systemic affects
Atropine percentage
1%
Cyclopentolate percentage
0.5% and 1%
Who is cyclo not recommended for
age and what is it a risk of
- Not recommended in children under 3 months due to risk of amblyopia.
How is cyclo prepared
Typically, both are in the form of Minims but can be as multi-use bottle (Eg. Mydrilate)
Cyclo class and age
It’s a POM
3months to 12 years 1%.
Over 12s 0.5%.
Cautions of cyclo
(3)
P,N,N
Pigmented irides. Narrow angles. Neonates.
Cyclo interactions
O,L,C
- Other muscarinic drugs
- Levodopa (used in Parkinson’s disease) cyclo reduces the absorption
- Clozapine; risk of developing intestinal obstruction
Side effects of tropicamide
- eye erythema- redness
- eye irritation (on prolonged administration)
- eye pain; headache
- hypotension- low blood pressure
- nausea
- Syncope- fainting
- vision blurred
Clinical uses of tropicamide
(4)
P,A,U,A
- Paediatric refraction
- Amblyopia therapy
- Uveitis- stops or reduces formation of posterior synechiae
- Alleviation of ciliary spasm
What is the gold standard for paediatric refraction
Atropine was the gold standard
Today Cyclopentolate 1% is the preferred choice
Benefits of atropine for paediatric refraction
-removes about tonic accommodation
-gives full cycloplegia
Disadvantages of atropine for paediatric refraction
T,S,N
-toxicity
-slow acting and long lasting
-not preferred for pediatric refraction
What are the components needed for ideal refraction
- fast-acting
- give adequate cycloplegia
- last long enough for the refraction to take place
- have no local or systemic side-effects.
What side effects can cyclopentolate cause that doesn’t make it the perfect drug for refraction?
It’s adequate but not a perfect drug
Can cause stinging and allergy
Local side effects of cyclopentolate
O,A
Ocular stinging
Allergy
Systemic side effects of cyclopentolate
C distrubances suich as 6
CNS disturbances such as:
Ataxia
Incoherent speech
Restlessness
Hallucinations
Hyperactivity
Disorientation.
How long should a child be monitored post cyclopentolate instillation
45 minutes
Optical penalisation study PEDIG
Study: Multi-centre RCT with 419 children.
Groups: Patching vs. Atropine.
Outcome: After 6 months, no significant difference in visual acuity improvement.
Key Finding: Both treatments are equally effective; patching is daily, atropine is twice weekly.
How is atropine used for amblyopia
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.
Advantages of atropine for amblyopia
It can reduce any hyperopic correction in the better seeing eye to also cause blur at distance.
How is atropine instilled
1% atropine was instilled every day, and the children were provided with sunglasses and advised to wear a hat
Disadvantages of atropine for amblyopia
Emmetropic patients will have significant blur at near
How is atropine used for amblyopia
Dosage: Weekend or twice-weekly atropine 1%.
Monitoring: Check adherence via pupil dilation (dynamic retinoscopy).
Non-response: Consider conventional patching.
Advantage: Long-lasting action preferred over cyclopentolate.
Anterior uveitis (iritis)
Definition, presentation, association, common
Definition: Inflammation of the iris and ciliary body.
Presentation: Young adults with a painful, red, uniocular eye, photophobia, and vision changes.
Association: May have systemic inflammatory diseases (e.g., rheumatoid arthritis).
Common: Often affects young adults.
How is the slit lamp used for examining uveitis
Cornea: Check for keratic precipitates.
Anterior Chamber: Assess for cells and flare (signs of inflammation).
Iris: Look for nodules or irregularities.
Lens: Examine for posterior synechiae.
Technique: Use focused beams to evaluate specific structures in detail.
What is used to treat posterior synechiae
steroids
How is uveitis managed
Acute/Chronic: Both types require medical evaluation.
Cyclopentolate 1%: Prevents/breaks synechiae and reduces pain by paralyzing ciliary movement.
Steroids: Prednisolone 1% (Pred Forte) to reduce inflammation.
Chronic Uveitis: Associated with juvenile arthritis.
What drug is given to alleviate ciliary spasm
Cyclopentolate 1% does this through cycloplegia
this is very uncomfortable and can be caused by corneal abrasion
What do all anti muscarinics cause
Pupil dilation (mydriasis)
This is because the sphincter papillae of the iris receives parasympathetic innervation.
More on mydriasis and pupils
- 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 innervation does the iris get
Sympathetic and parasympathetic innervation
Sympathetic- fight or flight response
Neurotransmitter for sympathetic system- noradrenaline
What is sympathetic innervation
fight or flight response
What are the parasympathetic innervations
A , PM
Accommodation, pupil myosis
What action do anti muscarincs affect
the action of the sphincter on the iris – cause mydriasis
What are all cycloplegia drops
Mydriatics
Summary about all cycloplegia drops being mydriatics
- To dilate the pupil a drop that doesn’t affect the parasympathetic system can be used- this mimics noradrenaline and allows dilator to be amplified
- Sympathomimetic system is mimicked e.g. phenylephrine and can give mydriasis without affecting accomodation
- adrenergic system is aided – amplifies
- To achieve best mydriasis a combination is used
Why are drug combinations often used
and whats their class
Drugs from separate classes are often used to create mydriasis
e.g. phenylephrine 2.5% and tropicamide 1%.
Which cases is a drug combination typically used
Assessing infants for signs of ROP (need full mydriasis for this)
Assessing adults when the peripheral retina needs to be seen in suspected retinal detachment.
In eye casualty need to use combination to visualize all the way to ora serrata
What is the best drug combination for mydriasis
phenylephrine 2.5% and tropicamide 1%.
Is atropine used as a mydriatic
- 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
Is cyclopentolate used as a mydriatic
- Cyclopentolate is more frequently used than atropine but its not the drug of choice as the cycloplegic affect is too great and lasts too long
- Cyclo is used in case of ineffective dilation with tropicamide or an allergy (POM)
Is tropic amide used as a mydriatic
- 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.
Phenylephrine 2% summary
available as and class
Available as Minim
It’s a pharmacy medicine (P)
What are the cautions when using phenylephrine
4 ADCD
Asthma
Long standing diabetes
Corneal epithelial damage
Darkly pigmented- resistant to dilatation and avoid overdosage
What are the cautions when using phenylephrine 10%
(7)
- It is a vasoconstrictor
- Can do same in lungs
- Caution in asthmatics
- 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
- cardiothoracic, breathing and heart complications- rarely used and if used has many issues
Phenylephrine drug interactions
Amitriptyline
Apraclonidine
Monoamine Oxidase Inhibitors (MAOIs)
Beta-adrenergic Blockers
Alpha-2 Adrenergic Agonists (e.g., clonidine)
Tricyclic Antidepressants
Ergot Alkaloids
Corticosteroids
Norepinephrine Reuptake Inhibitors (e.g., atomoxetine)
Alpha-adrenergic Blocking Agents (e.g., chlorpromazine)
Calcium Channel Blockers
Angiotensin-Converting Enzyme (ACE) Inhibitors
Benzodiazepines
Oxytocic Drugs
Atropine Sulfate
Sympathomimetic Agents
Acetaminophen (Paracetamol)
Antihistamines
Digoxin
Phenylephrine side effects
- Conjunctivitis allergic
- eye discomfort
- Systemic hypertension
- myocardial infarction (usually after use of 10% strength in patients with pre-existing cardiovascular disease)
- periorbital pallor
- vision disorders
Clinical use of phenylephrine
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
Risks of using phenylephrine
- 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 (original lens in place) female hypermetopes of East Asian descent are particularly at risk.
- Because iris is being pulled there is a risk of angle closure
- Females more at risk of angle closure than males
- Hypermetropes- more at risk because of small eyes
- East Asian- can cause angle closure
Why is a Van hericks assessment done and what is the grading
Van Herick’s Grading is a slit-lamp technique used to estimate the anterior chamber angle and assess the risk of angle-closure glaucoma:
Grade 4: Angle width >1:1 (Wide open, no risk of angle closure).
Grade 3: Angle width ~1:1 (Open, low risk of angle closure).
Grade 2: Angle width ~1:4 (Narrow, moderate risk of angle closure).
Grade 1: Angle width ~1:16 or less (Very narrow, high risk of angle closure).
Grade 0: No visible gap (Angle closed or very high risk).
Further clinical use of van hericks assessment
This method is essential in glaucoma risk assessment, especially in identifying primary angle-closure glaucoma (PACG).
Regular monitoring or further evaluation with gonioscopy is needed for narrow angles.
Which patients need dilation
-Indirect viewing techniques such as Volk lens examination with a slit lamp or headset mounted binocular indirect ophthalmoscopy.
-When viewing 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.
More on patients who need dilation
- The risk of missing ocular pathology outweighs the risk of inducing angle closure.
-Tropicamide is safe to use but patients must be advised if symptoms of angle closure
present. (Pandit & Taylor, 2000)
- Long term diabetic has higher risk of disease
- Sudden onset of flashes and floaters in myope
What is the best description of the mechanism of action of cycloplegic drugs?
They competitively inhibit acetylcholine at post-synaptic receptor sites, preventing ciliary muscle contraction.
Which drug is a sympathomimetic mydriatic with minimal effect on accommodation?
Phenylephrine
Whcich drug is used to break posteriour synechiae in uveitis
cyclopentolate
Which drugs is most likely to cause behavioral changes, such as hyperactivity or withdrawal, in children?
cyclopentolate
A 70-year-old patient with cardiovascular disease and narrow angles requires pupil dilation for fundus examination. Which of the following is the safest option?
tropicamide
A 3-month-old infant requires a cycloplegic refraction. Which of the following agents should be avoided due to the risk of amblyopia?
cyclopentolate
Which patients is at the highest risk of angle closure after receiving mydriatic drops?
A 60-year-old hypermetropic female of East Asian descent
A patient with a corneal abrasion presents with severe pain due to ciliary spasm. What is the best treatment to alleviate this discomfort?
cyclopentolate 1%
A 50-year-old female with diabetes and a history of angle closure glaucoma requires pupil dilation. Which agent is the safest choice?
tropicamide 0.5%
Which of the following correctly describes the primary function of the Edinger-Westphal nucleus?
Provides parasympathetic innervation to the sphincter pupillae and ciliary muscle
In patients with a history of cardiovascular disease, which drug poses the highest risk of myocardial infarction?
phenylephrine 10%
What describes the pharmacological classification of cycloplegic drugs?
parasympatholytics
How does phenylephrine cause mydriasis?
It enhances the activity of noradrenaline at the dilator pupillae muscle.
