There are many types of eye drop for glaucoma and they are grouped according to the way in which they work.
All types of drop may cause mild irritation. However, you should continue to use the drops and report any problems you have to the eye doctor at your next clinic visit. If you cannot tolerate the irritation, you should arrange to see your GP or eye specialist as soon as possible.
Some drops may cause an allergy. If the eyes become red and puffy, stop the drops and go to see your GP or eye doctor as soon as possible. If the drops make you feel unwell or breathless, stop the drops immediately and consult your GP as soon as possible.
1. Beta-blockers. This type of drop includes Timoptol, Nyogel, Teoptic, Betagan and Betoptic. These drops reduce the production of fluid in the eye and are used once in the morning or twice a day. The main possible side effect is asthma. You should not take these drops if you suffer from, or develop, asthma. However, most patients have no problems when they take the drops. Other possible side effects include a slow pulse, dizziness, tiredness or a reduction in the amount of exercise you can do. In some patients they may cause depression, loss of libido or impotence.
2. Alpha agonists. This type of drop includes Alphagan and Iopidine. These drops reduce the production of fluid in the eye and possibly improve the flow of fluid out of the eye a little. They are used two or three times a day. Possible side effects include a dry mouth and a feeling of being generally unwell. Alphagan may cause nightmares in children and should not be used in infants.
3. Prostaglandin/prostamide analogues. This type of drop includes Xalatan, Lumigan and Travatan. These drops improve the flow of fluid out of the eye through the non-conventional (uveo-scleral) outflow pathway and are used once a day, usually at night. Possible side effects include a pink eye that usually improves after a few days or weeks. The iris may darken in colour and the eyelashes may grow thicker and darker. Eye colour change is most common with green or hazel eyes, which become browner, and is least common with blue eyes.
4. Carbonic anhydrase inhibitors. This type of drop includes Trusopt and Azopt. These drops reduce the production of fluid in the eye and are used two or three times a day. Possible side effects include a bitter taste.
5. Cholinergic agonists. This type of drop includes Pilocarpine. This drop improves the flow of fluid out of the eye through the conventional outflow pathway and has to be used three or four times a day. A gel preparation, Pilogel, can be used once at night. The drop makes the pupil small and possible side effects include headache or eye ache (this usually wears off), blurred vision and darkening of the vision.
6. Combinations. Combinations of drops in the same bottle are available for patients who need more than one type of drop. These include Cosopt (Trusopt and Timoptol) and Xalacom (Xalatan and Timoptol).
There are several different types of eye drop for glaucoma and your eye doctor may need to change your treatment until the right drop, or combination of drops, is found.
Once eye drops have been started, they usually need to be taken for life (there is no such thing as a 'course of treatment' for glaucoma). In some patients, eye drops are not sufficient to control the eye pressure and so other treatments, such as tablets, laser therapy and surgery are appropriate.
Are there any other types of treatment?
Some patients develop glaucoma with a normal eye pressure (this is called normal tension or low tension glaucoma). It is believed that poor blood flow to the eye may contribute to the development of the optic nerve damage. In these patients, pressure-lowering drops are still the first choice of treatment. However, in some cases, tablets that affect the blood flow may be helpful, although there is limited scientific evidence for their benefit.
How should I take my eye drops?
It is worth getting into a routine, so that the drops are not forgotten. For instance, if you keep the bottle of drops by your toothbrush, you will remember to put the drops in when you brush your teeth.
There are various ways to put drops in the eye. One of the simplest is to sit in front of a mirror, pull down the lower lid and let the drop fall into the space between the eye and the lid.
Instilling eye drops
Close your eye and gently press on the inside corner of it with a finger for one to two minutes. This will help to slow the rate at which drops drain out through the tear duct into your system and keep them in your eye, where they are needed.
Closing the tear duct
Eye drops drain away through the tear ducts into your nose and then are swallowed. Consequently, you may be able to taste some eye drops.
Another way of putting drops in your eye is to tilt your head backwards while sitting, standing, or lying down. With your index finger placed on the soft spot just below the lower lid, gently pull down to make a space between the eye and the eyelid. Let a drop fall into the space.
If you take more than one type of drop, it is important to leave at least ten minutes between each drop to prevent the second drop washing out the first.
If you have difficulty telling if a drop has gone into the eye, keep your drops in the door of the refrigerator (not the freezer). Your eye will feel the liquid better when it is cold than if it is at room temperature.
Because damage to the vision in glaucoma is permanent, it is important to prevent it getting worse. For this reason, it is essential to take your eye drops if you want to keep your vision.
If you are still experiencing difficulty instilling your eye drops, please do not hesitate to contact our helpline, Sightline. Our friendly staff will be able to talk you through each step described above, discuss with you other ways of squeezing the bottle or aiming at your eye and if needed, they will also be able to advise you on the possible compliance aids which could help you.
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A form of water tablet, called Diamox, may be useful to help control the pressure in some cases. The tablets are usually a short-term treatment.
The tablet reduces the production of fluid in the eye and increases the amount of urine and salts leaving the body. If the tablets are used for more than a week, it is a good idea to eat a banana a day to help replace some of the salts.
The tablets can cause some patients to experience tingling in their hands, feet or lips, or nausea and tiredness. They may cause kidney stones in some patients after prolonged use. If you notice these side effects, tell your eye doctor.
Laser therapy is appropriate only in some patients and some types of glaucoma. Laser treatment is similar to the examination called gonioscopy. An anaesthetic drop is given to numb the front of the eye. The doctor holds a special lens against the surface of the eye and the laser is applied through the lens. The treatment is painless, although the patient sometimes feels a slight twinge.
There are two main types of laser therapy:
1. Laser trabeculoplasty. This is a treatment for open angle glaucoma and is successful in reducing the eye pressure in some patients. It is usually necessary to continue with some eye drops after laser trabeculoplasty. Laser therapy does not work in all patients and the effects of the laser may wear off in time. Laser spots are applied to the trabecular meshwork to stimulate the flow of fluid out of the eye.
Cross-section of eye showing laser trabeculoplasty
2. Laser iridotomy. This therapy is performed to treat or prevent acute angle closure and is given to prevent chronic angle closure getting worse. Following laser iridotomy for acute angle closure, drops to lower eye pressure may or may not be required. If the treatment is given for chronic angle closure, drops to lower eye pressure are usually still required. Laser spots are applied to make a small hole through the iris. This allows aqueous humour to flow freely into the front of the eye and prevents the iris being pushed forward onto the trabecular meshwork. The hole is usually hidden under the upper eye lid and cannot be seen.
Other forms of laser treatments are:
Peripheral iridoplasty and Pupilloplasty – these are treatments for angle closure types of glaucoma in which the laser treatment is directed at the iris.
Laser ciliary body ablation – this is a treatment for types of glaucoma in which it is difficult to control the eye pressure by other means. The laser is applied through the surface of the eye, behind the coloured part of the eye (iris), to the ciliary body. This reduces the production of aqueous humour and thus the pressure.
If eye drops or laser therapy have not succeeded in lowering the eye pressure, the doctor may recommend an operation to control the pressure. The most common operation is called trabeculectomy.
The eye has a tough outer wall (the sclera) which is covered by a thinner skin (the conjunctiva). In a trabeculectomy, the surgeon makes a flap over a small hole in the sclera. The flap forms a new passage for aqueous humour to leave the eye under the conjunctiva.
The trabeculectomy forms a small bump under the upper lid, called a trabeculectomy bleb. Sometimes is may be possible to see fine stitches. These stitches hold the flap in place.
The operation may be performed under local anaesthesia or general anaesthetic. With local anaesthetic, an injection is given next to the eye to numb the eye and you are awake during the operation (but you do not see what is going on). With general anaesthesia, you are asleep during the operation.
Red Ring indicates trabeculectomy bleb and cross section of eye showing trabeculectomy
How successful is the operation likely to be?
Five years after surgery, the eye pressure remains controlled in about 75 per cent of patients. If the operation fails to control the pressure some time after the surgery, the operation may be repeated or drops can be started again.
Some patients produce more scar tissue than other patients and the scar tissue may block the flap and prevent the operation working. If scarring is likely, the surgeon may recommend the use of anti-scarring treatment at the time of, or shortly after, the surgery.
Side effects and complications
Trabeculectomy may cause an existing cataract to develop more quickly. A cataract occurs when the lens in your eye becomes cloudy. This causes the vision to become misty and less clear. Cataract surgery – the replacement of your natural lens with a clear artificial lens – can be performed after a trabeculectomy.
There is a long-term risk of getting an infection in the eye after trabeculectomy. If you develop a red, sore eye at any time after the operation, then you should see an eye doctor immediately.
In some patients, a trabeculectomy is not the best operation and other forms of surgery maybe performed. These include viscocanalostomy, deep sclerectomy and 'tube' or 'valve' operations.
Viscocanalostomy is a relatively new technique developed for glaucoma surgery and was first proposed in 1991.
Whereas a trabeculectomy creates a 'flap' in the eye, allowing the aqueous humour to drain directly from the front of the eye to form a bleb under the conjunctiva, viscocanalostomy does not involve making a full-thickness hole into the front of the eye. Instead, the surgeon removes a block of sclera to leave a thin membrane (Descemet's membrane) through which the aqueous humour percolates. The aqueous then drains away either through Schlemm's canal (in the natural way) or under the conjunctiva. During the surgery, a thick fluid (visco-elastic) is injected into Schlemm's canal, hence the name of the operation – viscocanalostomy.
There are theoretical advantages over a trabeculectomy, such as a reduced rate of cataract development and lower risk of excessively low pressure after surgery. However, the amount by which the eye pressure is lowered by viscocanalostomy is not usually as great as that by trabeculectomy.
The deep sclerectomy operation is essentially very similar to the viscocanalostomy operation, with similar advantages and disadvantages.
It is usually performed with the insertion of a material (collagen implant) under the scleral flap to improve the drainage of aqueous humour under the conjunctiva.
'Tube' or 'Valve' operations
In these procedures, the surgeon places a small plastic tube in the eye. This allows fluid to drain out of the eye to a special reservoir under the conjunctiva (skin of the eye). This is usually hidden under the top eye lid. The fluid is absorbed from the reservoir back into the bloodstream.