Mydriatics and cycloplegics

Antimuscarinics dilate the pupil and paralyse the ciliary muscle; they vary in potency and duration of action. Short-acting, relatively weak mydriatics, such as tropicamide 0.5%, facilitate the examination of the fundus of the eye. Cyclopentolate 1% or atropine are preferable for producing cycloplegia for refraction in young children. Ocular side-effects of mydriatics and cycloplegics include transient stinging and raised intra-ocular pressure; on prolonged administration, local irritation, hyperaemia, oedema and conjunctivitis can occur. Contact dermatitis can occur with the antimuscarinic mydriatic drugs, especially atropine.

Antimuscarinics

ATROPINE SULPHATE:

Indications: Treatment of iritis and uveitis to immobilise the iris and ciliary muscle and to prevent or break down adhesions. Used for refraction in children less than six years old and in children with convergent strabismus.

Contraindications: Closed angle glaucoma. Patients with a narrow angle between the iris and the cornea. Known hypersensitivity to any component of the preparation, especially wool fat (ointment only).

Dose and Administration: Adult; Uveitis/iritis: approximately half an inch of the ointment into the conjunctival sac once or twice a day or as directed by the physician/one or two drops to be instilled into the eye(s) to a maximum of 4 times daily. Refraction: apply approximately half an inch of the ointment into the conjunctival sac one or two hours before refracting or as directed by the physician/one or two drops one hour before refracting. Child dosage; Uveitis/iritis: approximately half an inch of the ointment into the conjunctival sac to a maximum of twice daily or as directed by the physician/one drop to be instilled into each eye to a maximum of 3 times daily. Refraction: approximately half an inch of the ointment into the conjunctival sac to a maximum of twice daily for 1 to 3 days prior to the examination, or as directed by the physician/one drop to be instilled into each eye twice daily for 1 – 3 days prior to the examination.

CYCLOPENTOLATE HYDROCHLORIDE:

Indications: For mydriasis and cycloplegia in diagnostic procedures.

Contraindications: Should not be used in the presence of closed-angle glaucoma, or patients with a narrow angle between the iris and the cornea.

Dose and Administration: Adults: One drop followed by a second drop in 5 minutes. Although complete recovery usually occurs in 24 hours, 1 or 2 drops of 1% or 2% of pilocarpine reduces recovery time to 3 to 6 hours in most eyes. Children: Pre-treatment with CYCLPENTOLATE on the day prior to examination usually is not necessary. One drop is instilled each time at the time of refractions, followed 10 minutes later by a second application if necessary.

TROPICAMIDE:

Indications: For mydriasis and cycloplegia for diagnostic purposes.

Contraindications: Contra-indicated in narrow angle or closed angle glaucoma.

Dose and Administration: For refraction 1 or 2 drops in eye(s) repeated in 5 minutes. If patient is not seen within 20 to 30 minutes, an additional drop may be instilled to prolong mydriatic effect. For examination of the fundus, 1 drop 15 to 20 minutes prior to examination.

Sympathomimetics

PHENYLEPHRINE HYDROCHLORIDE:

Indications: For powerful and rapid dilation of the pupil and reduction of congestion in the capillary bed. Can also be used in uveitis and for the temporary reduction of intraocular tension in certain cases of glaucoma.

Contraindications: Closed angle glaucoma, cardiac disease, hypertension, diabetes, tachycardia, thyrotoxicosis and hypersensitivity to any component of the preparation. Also patients taking MAOI’s, tricyclic antidepressants and antihypertensive agents including beta-blockers.

Dose and Administration: One to two drops as often as required. One drop of solution may be applied to free recently formed posterior synechia. Repeat next day if necessary. For intraocular surgery apply 30 – 60 minutes before surgery.