The role of eye drops in treating glaucoma

Once a patient is diagnosed with glaucoma the most common treatment is with medication in the form of an eye drop. There are several different eye drops available to treat glaucoma but they all aim to lower the eye pressure (intraocular pressure) back to a more normal level. Sometimes more than one kind of eye drop is needed to treat glaucoma. Although eye drops are very effective there can be problems with there use. These include side effects, difficulty putting in the eye drops and remembering to use them regularly.

The medication that is most frequently in the initial treatment of glaucoma is called a prostaglandin analogue. Examples include Hysite, Lumigan and Travatan. These eye drops work by increasing the drainage of fluid out of the eye. They only need to be used once a day at night before bed. They are the safest eye drops to use as they rarely cause side effects that affect the rest of your body. However, they do have side effects that affect your eyes. These include redness and irritation (usually resolves after a few weeks), longer eyelashes, a gradual change in eye colour (usually not noticeable for years), and occasionally eyelid discolouraton.

Another medication that may be used as a first option is a beta-blocker (examples include Timolol and Timoptic XE). However this may not be suitable for all patients. It cannot be used in patients with asthma and those with certain heart conditions including heart failure and heart block, as it will make these conditions worse. Some patients may already be on this medication as a tablet as it is commonly used for high blood pressure treatment. Beta-blockers lower the eye pressure by decreasing the amount of fluid produced in the eye and can be used once or twice daily depending on the type of eye drop used. Unlike prostaglandin analogues, beta-blockers can occasionally be associated with side effects that affect the rest of your body. These include lung and heart problems in patients already with these diseases, sleep disturbances (including vivid dreams), lethargy, depression and impotence. In addition they can also cause eye side effects such as redness and irritation.
One way of helping to reduce side effects from these eye drops is called punctal occlusion – after you have put in the eye drops, gently close your eyes and lightly press on the inside corners of eyes for at least 90 seconds. This will help to reduce the about of medication that enters your circulation and is especially important to do if you are on a beta-blocker.

For many patients, their glaucoma will be controlled with just one of either of the above eye drops. Sometimes patients will need to be on both – usually a beta-blocker in the morning and a prostaglandin analogue at night. There are some situations however where ‘second line’ eye drops may be needed. For example – if one or both of the above eye drops are ineffective or not tolerated due to side effects. Sometimes the glaucoma is so severe that a very low eye pressure is needed and additional medications are required to achieve this. The most commonly used second line agents are alpha agonists and carbonic anhydrase inhibitors.

Alpha agonists (e.g. Alphagan) lower the eye pressure by reducing the amount of fluid produced in the eye but these need to be used at least twice daily. The main issue with its use is the side effects including allergy symptoms (red and itchy eyes), dry eyes and mouth, burning/stinging eyes, and blurred vision. Carbonic anhydrase inhibitors (e.g. Azopt, Trusopt) also need to be used twice a day and have similar side effects that can be troublesome for some patients. There is a tablet form of this medication called Diamox but this can have severe side effects so is only used in rare situations as an emergency measure for a short period of time.

For patients who are a more than one type of glaucoma medication, combination eye drops are available to make their use a little easier. This is where there are two medications within the same eye drop. Examples include Cosopt – which is a combination of a beta-blocker and carbonic anhydrase inhibitor, and Combigan – which is a combination of a beta-blocker and alpha agonist.

In summary, medications in the form of eye drops play a very important part in the treatment of glaucoma. There are several different medications available but they can be difficult to use and may be associated with side effects. If you are having problems using your eye drops or are experiencing side effects then it is important to let your specialist know, as there will be alternative treatment options available. Finally, it is important to use your eye drops as prescribed, as the most common reason for eye drops not working is that patients do not use them regularly.