Prostaglandin analogue eye drops

Key examples

• Latanoprost
• Bimatoprost

 

Common indications

• As first-line agents to lower intraocular pressure in open-angle glaucoma and ocular hypertension. Prostaglandin analogues are generally preferred over topical β-blockers (the main alternative class) as they cause fewer systemic side effects.

 

Mechanisms of action

• Elevated intraocular pressure (ocular hypertension) is a risk factor for open-angle glaucoma. Glaucoma is characterised by progressive optic nerve damage associated with visual field loss and eventually blindness. It is usually, although not always, associated with elevated intraocular pressure. Either way, lowering intraocular pressure reduces glaucoma progression. Analogues of prostaglandin F2α reduce intraocular pressure by increasing outflow of aqueous humour via the uveoscleral pathway. The exact mechanism for this is uncertain.

 

Important adverse effects

• Prostaglandin analogue eyedrops have few systemic side effects. Locally in the eye they may cause blurred vision, conjunctival reddening (hyperaemia), and ocular irritation and pain. They may also cause a permanent change in eye colour by increasing the amount of melanin in stromal melanocytes of the iris. This affects about one in three patients and is most noticeable when treatment is restricted to one eye.

 

Warnings

• Caution is needed when contemplating prostaglandin analogue treatment in eyes in which the lens is absent (aphakia) or artificial (pseudophakia); and in patients with or at risk of iritis, uveitis or macular oedema. In patients with severe asthma there is a theoretical risk of provoking bronchoconstriction, but in practice this does not seem to be a problem. It is certainly less of a concern than with topical β-blockers.

 

Important interactions

• There are no clinically important interactions.