The only drugs available for the treatment of glaucoma are those that reduce intraocular pressure (IOP). A topical beta-blocker (timolol, betaxolol, levobunolol, carteolol, metipranolol) or topical prostaglandin analogue (latanoprost, bimatoprost and travoprost) is usually the drug of first choice, but it may be necessary to combine these agents or add others, such as a topical sympathomimetic (brimonidine, dipiverine, adrenaline, apraclonidine), topical miotic (pilocarpine) or topical carbonic anhydrase inhibitor (acetazolamide, dorzolamide, brinzolamide) to get the IOP to the desired level. Oral acetazolamide may also be used.

Dosage regimen

* Beta-blockers are usually used once in the morning or twice daily.

* Prostaglandin analogues tend to be used once at night.

* Sympathomimetics are usually applied two to three times daily.

* Miotics are usually used three or four times daily.

* Carbonic anhydrase inhibitors are usually applied two or three times daily.

* Oral acetazolamide is usually given at 0.25-1g daily in divided dose.

Patient knowledge

* Does the patient understand the need for their medication? As patients can not directly see or feel any benefit from glaucoma medication, concordance may be an issue. Ensure they understand the need for regular dosing, and the consequences of compliance failure.

* Is the patient using more than one type of eye product? If so, ensure they know to leave at least ten minutes between the application of different types to prevent the second drops washing out the first.

Is the medicine working?

* Check the patient can apply the medication correctly. Elderly patients and those with musculoskeletal conditions may find it difficult to aim or squeeze a small container of eye drops or ointment. These patients may benefit from combination products, which cut the number of applications per day, and compliance aids such as eye drop dispensers.

* It is important to counsel in the regular and correct use of their medication to maximize the effectiveness of treatment. If medication is not working, patient should go back to their GP as another glaucoma eye drops may be added to their current medication.

Side effects

* Common side effects of beta-blockers include stinging, burning, pain and itching.

* Pink eye often develops in patients using prostaglandin analogues, but usually improves after a few days or weeks. Ocular irritation, pain, thickening and lengthening of eyelashes are the other common side effects.

* Sympathomimetics can cause severe smarting and redness of the eye. Other side effects include stinging, burning, pruritis and dry mouth.

* Headache and eyeache usually occur with miotics due to ciliary spasm. Other side effects include burning, itching, smarting, blurred vision and contracted pupil.

* Nausea, vomiting, diarrhoea and taste disturbance are common side effect with patients taking oral acetazolamide.

Monitoring

* Beta-blockers are contraindicated in patients with bradycardia, uncontrolled heart failure and asthma.

* Patient using prostaglandin analogue at the beginning of treatment should monitor for eye colour changes as brown pigmentation in the iris may occur

* Miotics should be used with cautions in cardiac disease, hypertension and asthma

* Acetazolamide is contraindicated in patients with severe hepatic and renal impairment. Patient should be advised to have their blood count monitored regularly as blood disorders and rashes can occur. If so, discontinuation is urgently required.

* Patients should be reminded of the need for regular intraocular pressure checks.

Lifestyle

* Double-check whether patients are taking any OTC medication. Look out for hayfever and travel sickness products as sedating antihistamines have significant antimuscarinic activity and should be avoided in glaucoma patients.

* Latanoprost eye drops should be kept in the fridge.

* All eye products should be discarded 28 days after opening.

* Remind patients to order their repeat prescription on time to prevent them running out.

* Patients on more than one eye medication may be confused about what to take when. Pointing out distinguishing features, such as bottle colour, may help.

Ken P.K Wan, community pharmacist, Clacton-on-Sea, Essex

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