Glaucoma is a disease that affects the eyes, causing the internal pressure inside the eyeball to become very high. If this is not relieved by glaucoma surgery, the high pressure can damage the optic nerve, causing blindness.

This article on glaucoma surgery is by Kathryn Senior, a freelance journalist who writes health, medical, biological, and pharmaceutical articles for national and international journals, newsletters and web sites.

There are two main forms of glaucoma – slow onset and fast onset. Slow onset glaucoma, also called open angle or chronic glaucoma, arises slowly over a long period of time with few signs that the eye pressure is increasing. It is usually recognised only when the damage is at an advanced stage. However, if it is detected early (most opticians test for it during a routine eye test), the first glaucoma treatment usually takes the form of medical treatment in which drugs are used to lower the eye pressure. If the condition doesn’t respond to this first-line treatment, glaucoma surgery is usually considered. This can be done using a laser technique or a conventional microsurgery method, or by implanting a drainage system.

Emergency glaucoma surgery may be considered for the second form of glaucoma, also called closed-angle or acute glaucoma. This arises very quickly, often causing eye pain, which urges people to seek medical help. Drugs can still be used but it is more usual for glaucoma surgery to be done quickly to relieve the pressure as soon as possible. Glaucoma surgery is also the main treatment for people with congenital glaucoma.

Laser glaucoma surgery

There are several methods of glaucoma surgery that involve the use of lasers:

Laser peripheral iridotomy (LPI) uses a YAG or an Argon laser to make a small hole in the iris of the eye, just under the upper eyelid. This allows the pressure between from front and back of the iris to come into equilibrium and it stops the iris bulging outwards. This works well in cases of acute glaucoma; it relieves the pressure within the eye and prevents it recurring. It also makes it less likely that you will develop chronic glaucoma in the future. This form of glaucoma surgery is done with a local anaesthetic and takes about 15 minutes.

Laser trabeculoplasty involves using an Argon laser, either hot or cold, to make a hole in the eye at the base of the cornea. This area functions to allow drainage to the fluid from the aqueous humour to the corneal chamber. By making a hole here, the natural drainage of the eye is enhanced. This type of glaucoma surgery seems to be a good long-term treatment for chronic glaucoma and it can be repeated if the effects wear off over time.

Laser assisted trabeculectomy is a modification of the conventional surgical technique used to treat glaucoma (trabeculectomy – see below). Instead of making a hole in the sclera to relieve eye pressure, a laser is used to trim the thickness of the sclera, allowing fluid to pass through. This has the advantage that the eye is left intact – there is no penetration of the eyeball. It, therefore, has fewer side effects that the conventional form of glaucoma surgery but it does require great surgical skill as the shaving of the sclera is done manually.

Conventional surgery

The most common form of conventional glaucoma surgical treatment is the trabeculectomy, done without the use of lasers. Microsurgery is used to cut a flap in the sclera, which does not extend to the full thickness of the tissue. The aim is to create a small window to allow fluid to escape. The area is protected by loosely fixing the flap back in place with some stitches. It does have the disadvantage that the flap is often visible as a bubble in the eye and you can get some scarring around the incision.

More aftercare is needed than after laser glaucoma surgery – antibiotic drops must be used several times a day for several days and you may need strong painkillers to cope with the discomfort that follows the operation. It is vital that you don’t rub your eyes afterwards – which can be very difficult, particularly when you are asleep. Most surgeons insist that you wear eye protectors during the night for quite a few days after this type of glaucoma surgery.

Glaucoma surgery to insert drains

If drugs fail to lower the eye pressure and conventional glaucoma surgery fails, it is possible to have a further operation to introduce drains in the eye to equalise the pressure. Several types of implants can be used – including ones with valves that prevent backflow of fluid back into the eyeball. The drain consists of a very thin tube put into the anterior chamber with a plate holding it in place. Scarring can occur and this can block the drain, which is why you may also be given drugs to prevent fibrosis (tissue thickening) at the time that this type of glaucoma surgery is performed.

It is not a cure

Although the various types of drug treatments and glaucoma surgery that are available can help to reduce eye pressure and prevent blindness, sometimes very effectively, it is important to recognise that there is no cure for glaucoma. This is a condition that needs to be managed and you may need to try several different treatments and undergo more than one form of glaucoma surgery to protect your sight.

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