Agents that dilate the pupil (mydriatics) and paralyse accommodation (cycloplegics) are not only used as aids in the examination of the eye and other ophthalmic procedures but also in the management of inflammatory conditions of the eye to treat or prevent the formation of adhesions between the lens and the iris.

Mydriasis can be achieved by two mechanisms: paralysis of the pupillary constrictor muscles (which is how antimuscarinic agents act) or stimulation of the dilator muscles. Cycloplegia results from paralysis of the ciliary muscles.

For ophthalmic procedures, agents such as homatropine (available at district hospital level), which has a more rapid onset and shorter duration of action than atropine, may be preferred. Recovery following administration of homatropine may take up to 3 days. However, cycloplegia with homatropine may be incomplete and for young children who are often resistant to the action of homatropine, other antimuscarinics such as cyclopentolate or atropine may be preferred.

Homatropine Hydrobromide
Solutions (eye drop), 1%, 2%

Indications: - mydriasis and cycloplegia; uveitis

Cautions: - see notes above,

Side effects: - transient stinging and raised intraocular pressure, on prolonged administration, local irritation, hyperaemia, oedema and conjunctivitis may occur: contact dermatitis; systemic toxicity may occur in the very young and the elderly.

Contraindications: angle closure glaucoma

Dose and Administration

For the determination of refraction, one or two drops may be instilled, repeated if necessary 5 or 10 minutes later.

Uveitis (treatment); one or two drops my be installed up to every 3 to 4 hours.

Storage: - store in airtight containers. Protect from light.