Glaucoma surgery (trabeculectomy)

Glaucoma is a condition where the optic nerve is damaged. The optic nerve carries visual signals from the eye to the brain. Damage to the optic nerve is usually caused by a build-up of fluid (aqueous humour) within the eye, leading to increased eye pressure (intraocular pressure or IOP).  

Glaucoma can lead to severe loss of vision or even total irreversible blindness if left untreated. However early detection and effective management can prevent visual loss in the vast majority of patients.

What is a trabeculectomy? 

Trabeculectomy is considered to be the gold standard of glaucoma surgery. It drains fluid from the front compartment of your eye (the anterior chamber) to relieve eye pressure. 

The procedure creates a new channel for the fluid to pass through and drain into a small blister under the eye’s surface (the conjunctiva), mostly hidden under your upper eyelid. 

By reducing the pressure in your eye with a trabeculectomy, the pressure on your optic nerve also decreases. This release helps to prevent the progression of vision loss caused by glaucoma, but it doesn’t necessarily restore the vision you’ve lost already. Unfortunately, there is no treatment or operation to restore the vision lost due to glaucoma, although in some patients, once the eye pressure is sufficiently reduced, there can be some improvement in visual fields.  

Who can have a trabeculectomy? 

Our ophthalmologists recommend trabeculectomy for moderate to advanced or progressive glaucoma, especially if other treatments, including eye drops or laser treatment, have not reduced the eye pressure to a sufficiently low level.  

If you have glaucoma in both eyes, your doctor will only perform a trabeculectomy on one eye at a time. 

How is a trabeculectomy performed? 

Surgeons usually perform a trabeculectomy under local anaesthetic. This means you will be awake throughout the surgery, but your eye will be numb, so you should not feel any pain.  

However, the surgeon can sometimes consider carrying out a trabeculectomy under a general anaesthetic so that you will be asleep throughout. Your consultant ophthalmologist will discuss your best option before you have the surgery.  

Once the anaesthetic has taken effect, your surgeon will make a tiny opening in the sclera (the white part of your eye) underneath your eyelid to create a small blister (bleb). They will then create a pathway for the fluid in your eye to travel through and drain into the bleb. This fluid bypasses the natural drainage system, which is blocked, to reduce the pressure in your eye. No implants are left inside during this procedure on its own. 

During the procedure, the surgeon will usually apply a medicine called mitomycin C (MMC) to the sclera to reduce scarring after the operation and help keep fluid draining from the eye.  

Our surgeons perform most trabeculectomies as day cases, so you would usually return home on the same day. The operation takes around 45 minutes to 1 hour to complete, and you will lie flat throughout. 

Your consultant will place a pad and plastic shield over your eye at the end of your surgery, which you must wear overnight for protection. They will also give you eye drops to use for several weeks after surgery to help your recovery.  

Preparing for a trabeculectomy 

Before your operation, you will attend a pre-assessment appointment with your consultant to check you are well enough to have the surgery. You will also discuss your anaesthetic options during your appointment and can ask any questions about the surgery and your recovery. 

At this appointment, you must tell your doctor or nurse about any other medications you are taking. Before your operation, they may adjust any blood-thinning tablets, such as warfarin. 

Unless your consultant ophthalmologist tells you to stop, you should continue using any eye drops and take any medications for your glaucoma as you typically would in the lead-up to your surgery.  Sometimes additional eye drops are given to reduce inflammation and prepare the eye for surgery.  

Recovering from a trabeculectomy 

After a trabeculectomy, you will most likely go home on the same day, but it can take a few weeks to recover fully. 

You can remove the protective pad and shield from your eye the morning after your surgery. You must start to use the eye drops your consultant gave you as directed.  

If you have glaucoma in both eyes, you must stop using your regular glaucoma drops in the operated-on eye but continue applying them to your other eye as usual. If you have been on a pressure reducing tablet called acetazolamide then this is stopped after the surgery. 

It’s normal for your eye to be watery and sore for 1-2 weeks after surgery. Your vision may also be blurry immediately after surgery, but it should slowly recover to similar levels as before the surgery. 

The bleb is typically made underneath your eyelid, so you shouldn’t notice it when you look in the mirror. 

You must attend follow-up appointments in the weeks after your operation so your consultant can check on your eye and ensure the drainage channel stays open. These post-operative checks are very important to adjust the pressure as needed and to check how you are recovering. Sutures are also removed as needed during this period. Sometimes different anti-scarring medications are needed in the post operative period. 

It’s essential to know that your glasses or contact lenses prescription may change after a trabeculectomy. Therefore, you should arrange an eye test around 3 months after the procedure. 

Benefits of a trabeculectomy 

A trabeculectomy is considered safe. It has a high success rate in reducing pressure within the eye of patients with glaucoma, providing a better chance of having protected vision with fewer eye drops needed. 

Risks of a trabeculectomy 

As with any kind of surgical procedure, there are risks.  

Complications of a trabeculectomy may include: 

• a cataract (cloudy lens) forming in the eye 
• bleeding inside or on the surface of the eye 
• blurring or loss of vision 
• collection of fluid under the retina 
• discomfort 
• double vision 
• drooping of the upper eyelid (ptosis) 
• eye pressure becoming too low or too high, requiring further surgery 
• infection, causing pain, redness, blurred vision, or loss of vision 

Your risk of developing any of these complications will depend on your age, health conditions and your eye condition. 

Your consultant will discuss any potential complications and risk factors with you in more detail at your initial consultation or pre-assessment appointment. 

Alternative treatments 

Eye drops are the main non-surgical treatment for glaucoma. If they’re not effective, there are other options apart from trabeculectomy. 

These include laser treatment, such as selective laser trabeculoplasty, and many other types of newer glaucoma surgeries, collectively known as MIGS (minimally invasive glaucoma surgeries), which can be used to reduce the pressure in your eyes. Your consultant will be able to discuss these alternatives with you and advise on the most appropriate course of action.