Trabeculectomy (also known as a type of filtering procedure) is performed in order to relieve eye pressure due to glaucoma. Glaucoma can damage the eye and cause a loss of vision.

During a trabeculectomy, a small opening is made into the part of the eye that contains the fluid that is under pressure, and a flap of tissues is sewn into place to cover the opening. The flap is positioned like a trap door that stays slightly open to allow the fluid within the eye to drain out through the opening. This decreases pressure within the eye. The flap is then covered by the clear tissue on the surface of the eye (conjunctiva). As the fluid drains from the eye, it creates a "bubble" (or filtering "bleb") over the flap. This bleb controls the rate of fluid drainage, and can often be seen as a "bubble" on the surface of the eye, but is usually covered by the upper lid.


  • All allergies.

  • All medications that you are taking, including over-the-counter preparations, dietary supplements, vitamins or herbal preparations, and any eye drops eye medication.

  • Any previous complications from this or other procedures.

  • Smoking history.

  • Possibility of pregnancy.

  • History of bleeding problems.

  • Any other health problems.


Risks of the procedure include:

  • Infection.

  • Bleeding.

  • Pain.

  • Too high or low eye pressure.

  • A continued need for glaucoma eye drops.

  • Cataracts in the future.

  • Blurred vision.

  • Vision loss.

  • Drooping eyelid.

  • Scarring, preventing drainage through the Trabeculectomy flap.


  • Several days before the procedure, you may have blood tests to make sure your blood clots normally.

  • You may be asked to stop taking blood thinners, aspirin, and/or nonsteroidal anti-inflammatory drugs (like ibuprofen) before the procedure.

  • You will usually be asked to stop eating and drinking at least 6 hours before the procedure.

  • Have someone accompany you to the procedure in order to drive you home.


  • The procedure may be performed while you are awake (local anesthesia) or while you are sleeping (general anesthesia).

  • You will be asked to change into a hospital gown.

  • You will lie on an exam table, and you will be connected to a variety of monitors to keep track of your heart rate, blood pressure, and breathing throughout the procedure.

  • You will have an intravenous line (IV) placed. If the procedure is to be done under local anesthesia, you will be given medication that numbs your eye and keeps it from moving during the procedure. You may be given some medicine to help you relax.

  • An instrument called a speculum will be used to keep your eye open.

  • During the operation, the doctor will look through a special operating microscope to be able to see your eye better.