Tests and treatments


What is it?

What is it?

Glaucoma is an eye disorder in which a person gradually loses fibres of the optic nerve, usually due to elevated eye pressure. A trabeculectomy is a surgery that lowers eye pressure, with the objective of slowing down any further worsening of the visual field and to maintain visual acuity as much as possible. This is accomplished in approximately 75% of the patients.

Additional worsening of the visual field can seldom be completely stopped. This is, among other things, due to age-related loss of the nerve fibres (separate from the worsening caused by glaucoma). Vision will not improve and there is no repair of the damaged nerve cells.

Additional eye drops to lower eye pressure are also necessary in approximately 50% of the patients (for either a short or long period). Some patients require a repeat surgery in certain instances (sometimes years after the first surgery).

What is the process?

What is the process?

The surgery

A glaucoma surgery is performed using local or general anaesthesia. During the surgery, a new tiny duct is made for the aqueous humour. It is made under a little flap placed under the upper eyelid, right at the edge of the white of the eye (sclera) and the iris. The aqueous humour, which is responsible for the elevated pressure in the eyeball, can exit the eye and go towards the space under the conjunctiva. This lowers the pressure in the eye. As a result of having the new duct placed, a small fluid-filled blister forms under the conjunctiva: the bleb. The water seeps out of the bleb and continues on to the blood vessels.

This surgery takes approximately one hour.

Check-ups after the surgery

The first check-up takes place in the hospital the day after the surgery with the surgery (or surgeon colleague): the operated eye is examined and eye pressure is measured. Starting the first day after surgery, you will also start using the eye drops you have been given. You may administer the eye drops in the morning (even before having the check-up with the physician).

In general, the subsequent check-ups are anticipated (although they may vary by patient):

  • day 1
  • week 1
  • week 2
  • afterwards, based on clinical examination

The first three check-ups after the surgery are especially and extremely important. For this reason, we schedule them in advance.

Risks and side effects with a trabeculectomy

Risks and side effects with a trabeculectomy

After the surgery, you will barely feel any pain in your eye. The first few months after the surgery, you will need to administer eye drops often — even more often than before.

As with any surgery, there are also risks with glaucoma surgery. The risks of excessive eye pressure are nearly always greater. The most common side effects or risks with this surgery are:

  • Too-low eye pressure: after the surgery, eye pressure is often very low. During the first few weeks (or months), this can make your vision less sharp than it was before. If the eye pressure remains too low for a long period, this can lead to a retinal condition called hypotonic maculopathy. In such cases, it will be necessary to operate on the eye again in order to suture the newly-made duct.
  • Eye pressure that is too high: the duct is a wound in the eye that may not heal or close shut completely. When that is the case, the eye pressure continues to be elevated. If this develops, it may be necessary to cut some of the sutures using a laser. This may be done as an outpatient procedure. It will rarely be necessary to repeat the surgery on the eye in order to manually open the flap or drainage duct.
  • Blood in the eye: after a trabeculectomy, there may be some bleeding in the eye which obstructs your vision. In most cases, the blood resolves spontaneously after a few days or weeks. It is sometimes be necessary to rinse out the eye. Important: inform your physician if you take blood-thinning medication. You must hold these medications before the procedure (in consultation with your GP and/or prescribing physician).

Other side effects and risks:

  • After this surgery, it is usually no longer possible to wear soft contact lenses. You may consult your ophthalmologist regarding hard contact lenses.
  • Over the long-term (e.g. years), a bleb may thin out and start to leak. This leads to an increased chance of infection on the interior surface of the eye. Such an infection is characterised by eye redness, pain and blurry vision. If you experience these symptoms, contact the emergency department or your own ophthalmologist.

More detailed information about the pre-operative preparation and post-operative care can be found in the leaflet below.

Only available in Dutch:

Centres and specialist areas

Centres and specialist areas

Latest publication date: 16/05/2024
Supervising author: Dr Vanwynsberghe David