Family doctor

Introduction

Glaucoma is a major cause of loss of vision. Open-angle glaucoma slowly happens over time, and by the time symptoms occur it is very late and some loss of eyesight will happen. This article will discuss the treatments for simple or open-angle glaucoma, and not for the sudden painful glaucoma, angle-closure or closed-angle glaucoma.

In many patients with simple glaucoma there is an increase in pressure in the eye that is higher than the pressure your eye can cope with, and this causes cupping of the optic disk and damage to the optic nerve, and long-term loss of vision.

Some people's eyes can cope better with high pressure than others so your optometrist will not only measure the pressure, but will also look for cupping of the optic disk and may check your visual field (how far around your vision goes when you are looking straight ahead).

The increased pressure is from fluid building up in a confined space, perhaps because the drainage system is not working very well. The pressure needs to be lowered to reduce the long-term loss of sight, and eye drops are the first choice for doing this.

If the first type of eye drops don't work then another type is usually trialed. Sometimes you may need two different types of eye drops at once. If this still doesn't reduce the pressure sufficiently, tablets may be used, or laser treatment or surgery may be required.

Eye drops or tablets will help to prevent loss of eyesight. To do this they must be used every day without missing any doses and are usually used for a lifetime, unless you undergo surgery or laser treatment.

Medicines and brands:

There are many different eye drops for glaucoma and they belong to different "groups" which are based on the way they work. The medicines are discussed by group below.

The eye drops reduce pressure either by increasing the drainage for the fluid in the eye, or reducing the amount of fluid produced. Because there are different groups, if one doesn't work or if it has side effects, there will be another one to try that may be a better choice for you.

All eye drops can be absorbed into the blood stream, and so they can cause side effects in other parts of the body, not just the eye. The eye drops usually contain a preservative that may be incompatible with contact lenses - if you use contact lenses check with your eye specialist if your eye drops will be compatible with your lenses.

Beta blocker eye drops

• Betaxolol (Betoptic)
• Carteolol (Teoptic)
• Levobunolol (Betagan)
• Metipranolol
• Timolol (Timoptol)

The beta-blockers are usually the first type of eye drops to start on because they are generally effective and well tolerated (meaning side effects are not a problem for most people).

These medicines must not be used in people with an extra-slow heart beat, heart block, uncontrolled heart failure and some other heart problems. They should not be used in people with asthma or emphysema because they cause tightening of the breathing passages. Special care may be needed in people with very severe allergies as the beta-blockers may increase the sensitivity in these people and affect their response to adrenaline. Special care is needed with the elderly and diabetics.

The most common side effect is probably eye discomfort for a short time. Other eye effects such as itching sensation, blurred vision, tear production or dryness of eyes are less common.

Side effects for other parts of the body are uncommon but can include slowing of the heartbeat, tightening of the airways, headache, and dizziness. Let your doctor know if you have any effects especially on the heart or breathing.

There are possible interactions with beta-blocker tablets (a heart medicine), reserpine, and some psychiatric medicines.

Miotics

• Pilocarpine (PV Carpine, Pilocarpine, Pilopt, Sno Pilo)
• Pilocarpine eye inserts replace once a week (Ocusert)
• Carbachol (Isopto Carbachol)
• Physostigmine

These eye drops have the difficulty of causing blurred vision and making the pupil small which reduces the amount of light going into the eye and reduces the field of vision. Pilocarpine has to be used frequently (e.g. four times a day) but also comes in an insert form called Ocusert that is placed under the eyelid and left there for seven days. Ocusert has continuous release of pilocarpine so is more convenient.

Carbachol is not used very often but can be helpful in people allergic to pilocarpine.

Alpha agonists

• Apraclonidine (Iopidine)
• Brimonidine (Alphagan)

These eye drops may be used if others have not worked well enough. Bimonidine is the more popular of the two.

These eye drops must not be used in patients who are allergic to any ingredient in the drops or to clonidine. Care needs to be taken in patients with severe heart disease, depression, Raynaud's disease, low blood pressure, thromboangiitis obliterans, depression, and poor blood flow to the head or heart.

These eye drops can react with other medicines so always check with your doctor or pharmacist if you are taking any other medicines.

Side effects include dizziness and sleepiness (do not drive if affected), and dry mouth. Red eyes, itching, swelling of the eyelids, and tear production show allergy. If these symptoms occur talk to your doctor or pharmacist.

Carbonic anhydrase inhibitors

• Acetazolamide tablets (Diamox)
• Dorzolamide eye drops (Trusopt)

Usually the tablets are a last resort due to their side effects, which include tiredness, depression, reduced appetite, altered taste and stomach upset including diarrhoea.

The eye drops are less problematic with the most common side effects being bitter taste (which doesn't last long) and burning or stinging of the eyes. Therefore, the eye drops are treated differently to the tablets and can be tried early in the treatment of glaucoma.

Others

• Latanoprost (Xalatan) - a prostaglandin-type eye drop
• Dipivefrine (Propine, Dipoquin) - adrenaline type
• Adrenaline (Eppy, Simplene)
• Pilocarpine + timolol (Timpilo)

Latanoprost is a new product for glaucoma used mainly if the other eye drops are not working well enough, or if other eye drops have problem side effects for a person. It is used once daily, at night. Possible side effects include a change in eye colour, growing of eyelashes and darkening of the skin around the eyes.

Adrenaline is not often used but dipivefrine is quite common as it has fewer side effects than adrenaline. Dipivefrine can cause red eyes.

Patient information:

• Follow the instructions on the label of the medicine or as directed by your doctor.
• The medicine must be used every day to keep the pressure in the eye down continuously. Do not miss any doses.
• Throw your eye drops away one month after first opening. It may be useful to record the date of opening or the date to be thrown away on the bottle or on a calendar. If eye drops are used after this month there is a risk of contamination with bacteria which can then cause an eye infection.
• There is a family link with glaucoma, so if you have been diagnosed with glaucoma, your close relatives should also be checked for glaucoma.
• For many of these eye drops it is wise to shake the bottle before each use (check the box).
• Sometimes it is recommended to apply gentle pressure to the skin on top of the tear duct straight after using eye drops to help reduce the amount going into the blood stream.
• Let your doctor know if you are having any problems with your eye drops as another eye drop may suit you better.
• Keep your eye drops away from direct sunlight and away from heat.
• If you have other eye problems (e.g. infection or injury) check with your doctor about whether to start on a new bottle of your glaucoma eye drops. This is because you may be more likely to have problems with contamination of the eye drops in this case.
• Always wash your hands well before using the eye drops. Avoid touching the tip of the eye drop bottle to the eye or with your hand. Replace the cap promptly on the bottle.