Cyclopentolate
Mydriatics and cycloplegics
Mydriatics and cycloplegics
An antimuscarinic eye drop that paralyses focusing and dilates the pupil, used to measure refraction. Stronger and longer than tropicamide.
Quick facts
- Group
- Mydriatics and cycloplegics
- Target
- Muscarinic acetylcholine receptors of the iris sphincter and ciliary muscle
- Used for
- Cycloplegic refraction
- Key effects
- Stinging · Blurred vision and light sensitivity
- Monitor
- Behaviour · Feeding tolerance
- ATC
- S01FA04
No doses: the clinician sets them by the current guideline.
Mechanism of action
Cyclopentolate blocks muscarinic receptors of the iris sphincter and the ciliary muscle. With accommodation paralysed, the true refractive error can be measured, which matters most in children, who focus strongly. It acts faster and wears off sooner than atropine, but more slowly than tropicamide.
- Cyclopentolate blocks muscarinic receptors in the eye
- The ciliary muscle relaxes: accommodation is paralysed
- The pupil widens; true refraction can be measured
Indications
- Cycloplegic refraction (measuring refractive error with accommodation paralysed) Refractive errors and presbyopia →
- Pupil dilation for eye examination
Adverse effects
Common
- Stinging, irritation, redness
- Blurred vision and light sensitivity
- Conjunctivitis, keratitis
- Fast heart rate
Contraindications
- Hypersensitivity to any component
- Caution: Down syndrome; children with spastic paralysis or brain damage
Key interactions
- Carbachol, pilocarpine or ophthalmic cholinesterase inhibitors
- Cyclopentolate can counteract their pressure-lowering effect
What is monitored
- Behaviour, heart rate and breathing in children
- Feeding tolerance in infants after the exam
Administration and safety
- For the eye only; never injected.
- Pressure on the lacrimal sac for a few minutes after the drop reduces systemic absorption.
- In infants, feeds are held for four hours after the examination.
Pregnancy and breastfeeding
No animal reproduction studies exist; it is used in pregnancy only if clearly needed.
Nursing care
- Before giving it to a child, check for Down syndrome, spastic paralysis or brain injury.
- Watch for restlessness, confusion, hallucinations, flushing or a fast pulse after the drops.
- Warn about blurred vision and glare; no driving while dilated; sunglasses help.
Pharmacokinetics
- Onset and duration
- Maximal cycloplegia about 25–75 minutes after the drop; focusing usually recovers within 6–24 hours, while full pupil recovery can take several days
Test yourself
Think of the answer, then tap the question to see it.
Why is cyclopentolate used before measuring refraction in children?
It paralyses accommodation, so the true refractive error can be measured.
Which infant-specific precaution follows a cyclopentolate exam?
Feeds are withheld for four hours because of feeding intolerance.
Which systemic toxicity is typical of antimuscarinic eye drops in children?
Central nervous system effects: agitation, psychosis-like reactions and seizures, with a fast pulse.
Connections
← Back to the class: Mydriatics and cycloplegics
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: DailyMed - CYCLOPENTOLATE HYDROCHLORIDE solution/ drops (DailyMed (U.S. National Library of Medicine), 2026); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).
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Representative model, for educational purposes only.