Cyclopentolate 1% Eye Drops (Mydrilate)

How it works

It competitively blocks muscarinic receptors on the iris sphincter and ciliary muscle, producing pupil dilatation and temporary paralysis of accommodation.

Prescribing in practice

• Systemic antimuscarinic toxicity (central nervous system disturbance, flushing, tachycardia) can occur particularly in infants and young children, so use the lowest effective strength and apply nasolacrimal occlusion.
• May precipitate an acute rise in intraocular pressure in eyes with a narrow anterior chamber angle, so caution is needed in those predisposed to angle-closure glaucoma.
• Effects on vision and accommodation can persist for some time, longer than with shorter-acting mydriatics.

Monitoring

Observe young children for signs of systemic antimuscarinic effects after instillation, and assess the eye for any pressure rise in those with narrow angles.

Counselling the patient

• Your vision will be blurred and you may be sensitive to light for several hours, so do not drive until it has worn off.
• Wear sunglasses and report any eye pain, redness or visual disturbance.
• In children, press gently on the inner corner of the eye after drops to reduce absorption.

Evidence & guidelines

Cyclopentolate is a long-established cycloplegic supported by standard ophthalmic practice and the relevant SPC.