Specialists who treat this condition
Mr Mark Batterbury
What is glaucoma?
Glaucoma is a very common condition of the eyes. It is especially common in elderly people, and may run in families.
Glaucoma causes loss of your so-called peripheral vision. Imagine that you are crossing the road. You look at the other side, but are aware of approaching cars. Your peripheral vision allows you to see the approaching cars without actually looking at them.
What causes glaucoma?
Our eyes are filled with a water solution, which is constantly being made and draining away through a sieve-like structure. If the drainage sieve becomes silted up, too little of this solution leaves the eye and the pressure within the eye rises.
This is the most common form of glaucoma, primary open angle glaucoma.
The pressure damages the optic nerve, which transmits sight from the eye to the brain.
How do I know if I have glaucoma?
Usually you will not, since it doesn’t cause any symptom.
In particular, it does not cause headache or eye strain or blurring of vision.
However, an eye test, in which the eye pressure is measured, the nerve examined and the field of vision tested, is usually enough to detect it.
How does glaucoma affect me?
Most people with glaucoma, even those on treatment, do not lose sight because of their glaucoma. The loss of peripheral vision can be monitored by your ophthalmologist, but rarely does it become noticeable.
Can glaucoma be treated?
Drops, which lower the eye pressure, are prescribed.
There are several different types of drop. Your ophthalmologist will choose the most appropriate one or the best combination for you.
Sometimes an operation is required, to make a new drainage channel (like a valve) on the surface of the eye, covered up by the eyelid.
What happens if I forget to use my drops?
You should not worry! Although you should use the drops regularly and make sure that you never run out, you won’t lose your sight from missing the occasional drop.
If you do happen to miss a drop, don’t put in extra drops; simply wait until the next drop is due.
Primary open angle glaucoma is the most common type. What other types occur?
Very often the eye pressure is high but there is no damage to the optic nerve and no loss of peripheral sight. This is called ocular hypertension, a condition that should be monitored by your ophthalmologist.
Paradoxically, there may be glaucoma-type damage to the optic nerve and field of vision without high eye pressure. This is called normal (or low) tension glaucoma. The treatment of this is controversial and should be discussed with your ophthalmologist.
How often do I need to be seen?
If you have glaucoma, you will need to be seen about twice a year, and you should have a field test about once a year, depending on how you are getting on.
If you do not have glaucoma and are over 40, and especially if glaucoma is in the family, an eye test every couple of years should be sufficient.
Surgery for glaucoma
Eye pressure is a balance between how much fluid gets into the eye and how much leaves the eye. Glaucoma surgery can either reduce the amount of fluid getting into your eye (“turning off the tap”) or increase the amount getting out (“pulling the plug”).
Trabeculectomy ("pulling the plug") to increase the amount of fluid getting out of the eye
Draining the tubes and Ahmed valve (“pulling the plug”) to increase the amount of fluid getting out.
Cyclodiode Laser (“turning off the tap”)
What are the benefits of having glaucoma surgery?
By lowering the eye pressure, the glaucoma damage is slowed or stopped altogether.
What are the risks of having a glaucoma surgery?
As with any procedure, there may be risks involved and you should discuss these fully with the Consultant before your operation. The most common risks are:
Bleeding inside your eye, which clears up on its own
Blurring of sight, which is usually temporary
Over-drainage causing low pressure. This can make the sight blurred and create a shadow. This is usually temporary.
Scarring, which causes the pressure to rise.
Formation of a cataract, which may need removal at a later stage.
Loss of sight. This is rare. If the glaucoma is already very bad, the sight can suddenly vanish.
Many people experience a variety of non-specific symptoms, such as foreign body sensation, watering, and a feeling of a bulge under the top eyelid, amongst others.
Trabeculectomy is an operation, which creates a drainage channel to let fluid out of the eye and lower the pressure. The channel acts like a valve. A modification of trabeculectomy is non-penetrating surgery (deep sclerectomy), which may be more appropriate for some individuals.
The operation is sometimes performed at the same time as a cataract extraction if your eye specialist believes you may benefit from this additional procedure.
The operation site is located under the upper lid. The fluid passing out through the valve collects within the membrane covering the eye (the conjunctiva) and is absorbed into the eye through the blood circulation. The fluid collects in a blister or bleb. Sometimes the valve "sticks" due to growth of scar tissue, stopping fluid getting out of the eye.
Anti-scarring drugs such as 5 fluorouracil (5FU) or Mitomycin C may be used during and after the operation to help the new channel to drain more effectively.
Drainage tubes and Ahmed valves
In some eyes with glaucoma there may be reasons why a trabeculectomy would have little chance of success (for example an eye with a lot of scarring from previous operations). In such an eye we will implant a tiny tube inside your eye to allow fluid to drain from the eye to a plastic receiver attached to the back of the eye.
Here the laser beam is used to transmit energy through the wall of the eye to kill off the cells that are producing too much fluid.
What sort of anaesthetic is used?
Glaucoma surgery is not a painful operation and takes about half an hour. Therefore many people are happy to stay awake during the surgery; an injection of local anaesthetic around the eye helps to prevent any discomfort.
Some people are not suitable for local anaesthetic surgery, or do not like the thought of staying awake. These people have a general anaesthetic.