Ophthalmology/Mydriatic & cycloplegic

Mydriatics & cycloplegics

also: tropicamide · cyclopentolate · atropine · phenylephrine

Overview

Drops that dilate the pupil (and paralyse accommodation) — for fundoscopy/examination and to relieve pain/synechiae in anterior uveitis.

Mechanism

Antimuscarinics (tropicamide, cyclopentolate, atropine) block the iris sphincter + ciliary muscle → mydriasis + cycloplegia. Phenylephrine is an α₁-agonist → mydriasis WITHOUT cycloplegia.

Indications

Pupil dilation for fundus examination
Anterior uveitis (cycloplegic — relieves ciliary spasm + prevents synechiae)
Cycloplegic refraction in children

The agents

Tropicamideshort-acting antimuscarinic

hours

Routine fundoscopy.

Cyclopentolateantimuscarinic

Uveitis, paediatric refraction.

Atropinelong-acting antimuscarinic

days

Uveitis (prevents synechiae).

Phenylephrineα₁-agonist

Mydriasis without cycloplegia.

Adverse effects

Can precipitate acute angle-closure glaucomaserious

Dilating a narrow-angle eye — the key caution.

Blurred vision, photophobia (cycloplegia)common

Systemic antimuscarinic effects (esp. children/atropine)common

Cautions & contraindications

Untreated narrow/closed angleall

Precipitates acute angle-closure.

Interactions

Monitoring & kinetics

Warn re driving (blurred vision); angle assessment

Topical. Warn patient vision will be blurred for hours (tropicamide) to days (atropine).

Source: BNF — Mydriatics & cycloplegics