Glaucoma surgery

What is a trabeculectomy?

It is an operation performed to treat glaucoma. The operation entails forming a small channel through the white part of the eye.  This channel will allow fluid (aqueous) - made naturally in the eye - to drain away. Some patients will require a special medication (Mitomycin C) to be placed around the incision site to try to ensure that the channel does not scar over. The drainage site is under the upper eyelid and will not be seen, and once settled should not cause you discomfort. The fluid will drain from the channel and be absorbed by conjunctival vessels in the skin of the eye.

Do I have to have an operation, or can I have other forms of treatment?

Glaucoma can be treated with eye drops, which have to be instilled every day throughout the patient's life time. If treatment with eye drops fails to control the pressure in the eye, an operation may be necessary. Laser treatments are suitable for some patients but are not always permanently effective in lowering pressure. In other cases an operation or laser treatments may not be essential, but may be offered as an alternative to instilling eye drops constantly. 

Will I be awake or asleep during the surgery? 

Patients having this surgery can have it under a general or local anaesthetic (the eye is numbed with special fluid drops and a local injection with the patient remaining awake).


How long will I be in hospital after the operation? 

Most patients can go home the same day of surgery assuming they have good vision in the other eye or have someone with them that evening. Patients can choose to stay overnight if this may be difficult. 


Will the operation improve my sight?


Unfortunately, the operation cannot bring any sight that has been lost. After the operation, your sight may be blurred and seem worse. This is only a temporary situation, and is expected after an operation. Your eye will need time to heal and settle down following surgery. This generally takes about 6-8 weeks in total. 


How successful is the operation? 

Evidence shows that surgery is most effective at lowering eye pressure and the lower the eye pressure, the lower the risk of blindness from glaucoma. It is a very successful operation, which will in most cases, save the remaining sight of the eye.  Following surgery, in up to 80% of cases no further treatment is necessary.  In 10-15% of cases, drops to reduce pressure will still be needed.  In 5-10% of cases, further treatment or operation may be necessary.  


There is a small risk of bleeding in the eye at the time of surgery.  This usually clears gradually.  There is also a small risk of over drainage so the pressure is too low.  This usually settles but may need extra treatment.  There is also a very rare risk of late infection.  The rate of development of a cataract may become accelerated after glaucoma surgery, and this may require lens surgery to improve your vision.


What are antimetabolites and why are they used?

Mitomycin C and 5-FU decrease the amount of scar tissue formed around the new drainage site, thereby increasing the flow of fluid in this new channel, and helping to keep the pressure low. They can be used during and/or after surgery. They do carry a small increased risk of infection, and corneal complications, but can increase your chances of success.

Are there alternative surgical procedures?

There are a variety of types of surgery for glaucoma depending on the individual needs of the patient. Non penetrating surgery (Deep Sclerectomy, Viscocanalostomy, Canaloplasty) or less invasive glaucoma procedures (MIGS) using microscopic stents (iStent, Preserflo Microshunt, gel stent) can also reduce the number of glaucoma drops you use and lower your eye pressure but may be less effective than a trabeculectomy.


A website summarising the different types of minimally invasive glaucoma surgery can be found hereMr Nguyen can discuss the full risks and benefits based on your eye condition.


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This website exists to provide further information about ocular conditions to patients, and their families, optometrists and GPs.

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