Glaucoma medication

[14/03/2012]

Glaucoma medication

After glaucoma has been diagnosed, the vast majority of the time, your ophthalmologist will start treatment with eyedrops. Eyedrops are used to lower the intraocular pressure and is required lifelong. There are many different types of eyedrops for glaucoma and they have different modes of action - some may be more effective in one individual compared to another.



Eyedrops for glaucoma have become very effective over the years. Sometimes when one drop is insufficient to control the pressure, different eyedrops may be used in combination. For even better convenience, pharmaceutical companies have also made fixed combinations of glaucoma eyedrops so that one bottle will contain 2 different types of medication.

There are many different types of glaucoma eyedrops and they work differently to lower the intraocular pressure (IOP):

Beta Blockers

These are a very commonly used form of medication and it reduces the IOP by reducing the production of aqueous in the eye. (As mentioned previously, a balance between the production and outflow of aqueous within the eye is necessary to maintain normal IOP.) Examples of trade names for these beta blocker eye drops are Timoptol, Optimol, Carteolol, Betagan, Betoptic. They are usually prescribed twice daily (12 hours apart) and a single drop into the eye is sufficient each application.

All medications have side effects and eyedrops are no different. There is always the very small risk of allergic reaction but in relation to beta blockers, individuals with heart failure, asthma and slow heart rates should consult with their doctor before starting this eye drop.

Alpha agonists

These class of drugs work by acting on different receptors as the beta blockers - they also reduce IOP by reducing aqueous production but also increase uveoscleral outflow. Eyedrops in this class would include apraclonidine and brimonidine (Alphagan). Alphagan has also been reported to have a neuroprotective effect i.e. it may a separate positive effect on the optic nerve which is not related to the intraocular pressure lowering.

Common side effects are more local than systemic i.e. red eye, itchy eye, tearing. Less commonly, it can cause dry mouth, palpitations, difficulty breathing.

Prostaglandin analogues

This class of drug is the most recent addition to the collection of glaucoma eyedrops (but has been around since 2000). It works by increasing uveoscleral outflow of aqueous and is arguably the most effective of all the glaucoma medications. The currently used drops include Xalatan (Latanoprost), Travatan (Travoprost), Lumigan (Bimatoprost) and the latest one released only a few months ago, Zioptan (Tafluprost).

Common side effects include red eye, itchiness, increase pigmentation of eyelids and iris and increased length of eyelashes.

Carbonic anhydrase inhibitors

These are sulphur-based drugs (people with sulphur allergies - beware!) and they reduce the intraocular pressure by reducing aqueous production. Commonly used eyedrops are Trusopt (Dorzolamide) and Azopt (Brinzolamide). Diamox (Acetazolamide) is available in tablet or injection form which is very useful to help lower pressure quickly in certain emergency situations.

Local side effects include itchiness, redness and allergic reactions. The oral form can cause decreased appetite, kidney stones, low potassium levels and anemia.

Cholinergics (miotics)

This class of drugs have been used close to 100 years ago and it is only used nowadays mainly to treat acute attacks of high pressure in closed angle glaucoma. They reduce pressure in the eye by reducing inflow of aqueous and increasing outflow. It is not often used now because it causes constriction of the pupils and can result in reduced vision in dim lighting, headaches and rarely, retinal detachment. The most common eye drop is Pilocarpine.

Compliance with treatment

Applying eye drops may seem simple enough but believe me when I say, there are many people who either do not know how to do so (keep missing) or clean forget to put them in. Studies have shown that up to 25% of glaucoma patients take none of their medication! The number is probably higher for those who actually forget now and again. When the medication is not used, the intraocular pressure is obviously not controlled and there is progressive damage to the optic nerve. It is therefore, very important that patients remember to put their drops and do so correctly.

Below is a video on how to apply eyedrops correctly.