Trabeculectomy with Mitomycin-C

What is trabeculectomy with mitomycin-C?

Trabeculectomy is a type of glaucoma surgery that involves cutting through the surface tissue (conjunctiva) of the eye. A small trapdoor is created in the wall of the eye (sclera). Under this, a new drainage channel is created which drains fluid from the front chamber of the eye to a ‘bleb’, which is a reservoir covered by the natural outer membranes of the eye (conjunctiva). Fluid in the bleb is gradually absorbed by the body.

A medication called mitomycin-C is used during surgery to reduce scarring and increase the success of the operation.

Why do I need this procedure? The main purpose of trabeculectomy is to lower the eye pressure.

You may have been advised to undergo this procedure if your eye pressure is uncontrolled on glaucoma eye drops or to prevent progression of your glaucoma.

It is important to note that the trabeculectomy itself does not improve vision but may reduce your dependence on medications if successful. Any loss of vision due to glaucoma cannot be reversed either by medications or surgery, and the aim of treatment is to control the disease and prevent worsening.

What are the preparations?

Before surgery:

• Continue your glaucoma medications up to the day of surgery

• If you are on anti-platelet or anati-coagulant medication, you will have to stop these prior to surgery. Your doctor will advise you accordingly

After surgery:

• Use your eye drops and other medications as instructed and attend eye reviews with your doctor as arranged

• Use an eye shield while sleeping for 3 weeks after surgery

• Avoid eye exposure to tap water for 2 weeks after surgery

• Avoid strenuous activities for 2 months after surgery

• Do not go swimming unless your doctor has informed you it is safe to do so

How is the procedure performed?

The procedure is done as a day surgery. Either general anaesthesia or regional anaesthesia will be used to keep you comfortable.

You will be lying on the operating table for 45 to 60 minutes while the surgery is performed, as described above. Thereafter, you will be monitored for 1 to 2 hours before being discharged home.

What are the chances of success for this surgery?

Your glaucoma specialist is the best person to give you an idea of the success rate. This may vary from 60 - 90%, depending on the patient, and the severity and type of glaucoma. The aim of surgical treatment is to reduce eye pressure. A secondary aim is to wean off glaucoma eyedrops. It is important for you to understand that the main aim of eye pressure reduction is

to preserve remaining nerve fibres and prevent further nerve damage. Occasionally, the operation may not work as well as intended due to various factors.

In these cases, glaucoma eyedrops may have to be restarted to control the eye pressure adequately. Do remember that in glaucoma surgery, success means good eye pressure control without further visual loss, not improvement in vision.

What are the risks and complications of the procedure?

The following list is not exhaustive but mentions the most important complications:

Mild

• Transient blurring of vision: This is often temporary and usually resolves after about 1 month

• Low eye pressure: Occasionally, the eye pressure can be low from a few days to weeks and this can induce swelling at the back of the eye which can impair vision. This usually resolve after some time

• Ptosis (droopy eyelid): Occasionally, following the procedure, it is possible to have drooping of the upper eyelid. This may require another separate operation to restore normal lid position

• Corneal swelling: The cornea or “windscreen” of the eye may swell up, usually following difficult surgery. Vision is temporarily distorted, and usually recovers without special treatment. In patients who have diseased or “weak‟ corneas, the swelling may persist, requiring a second operation to improve the vision

• Cataract formation: If Phacoemulsification is not performed at the same sitting

Severe

Fortunately, these are very rare. They include:

• Infection (1 in 1000-2000 chance) following surgery

• Sight-threatening bleeding within the eye (1 in 1000-2000) at the time of surgery, or soon after

• Severe drop in eye pressure: In some very rare instances, if the eye pressure drops too low after surgery and vision is affected, a second operation may be needed to tighten up the artificial channel and adjust the eye pressure

• Operation failure: In some instances, the operation may fail and glaucoma eyedrops may need to be re-started for adequate control of eye pressure

• Loss of the central visual field (“Wipe-out”): Rarely, in older patients with advanced damage due to glaucoma, central vision may be permanently lost suddenly after surgery

What can I expect after the procedure?

1. Sensations: After trabeculectomy surgery, it is normal to feel some discomfort and mild pain after surgery due to the presence of some stitches. This should very quickly subside but in some cases, it may persist up to 4 weeks. You may also have some tearing and be sensitive to light for a short time. Care should be taken to avoid rubbing the eye.

2. Vision: Your vision may be blurred for the first few days and there may be slight redness or swelling. These will gradually disappear.

3. Medications: You will need to apply eye drops diligently, to aid healing and prevent infection following surgery, and other medicines that your doctor may prescribe. These will be tapered off over three to six months or so.

4. Precautions: The eye should not be rubbed during the first few weeks after surgery. You may be asked to wear a shield over the operated eye, particularly while sleeping. For the first few weeks, be careful not to get any water, face cream, soap or shampoo into the operated eye.

5. Follow-up visits: You can expect to be followed-up closely for the first 3 weeks. In the following 6 months, you may also be required to undergo a series of injections to the surface of your eye to facilitate the success of your operation. These will be done during your regular visits to the eye clinic and do not require any preparation on your part. In some patients, stitches may also have to be removed to fine-tune the eye pressure. This is easily and painlessly performed in the clinic.

6. Activities: You may resume most normal activities after 1 to 2 weeks following surgery. Activities such as reading, watching television and cooking will not hurt the operated eye. Try to avoid bending at the waist or heavy lifting for 3 to 4 weeks after surgery. Light exercise like walking is allowed 6 weeks after the surgery. Swimming is prohibited.

7. Diet: There are no special dietary restrictions following surgery.

8. Glasses: Most surgeons recommend waiting about 4 to 6 weeks before prescribing glasses.

What are the other Options? Your glaucoma specialist is the best person to give you an idea of the other options available to you apart from this surgery and what would happen if you do not undergo the procedure.

What will happen if I do not undergo the procedure? There is a risk of progressive vision loss or blindness if your eye pressure is not well controlled.

DISCLAIMER: This information sheet mentions some of the more common or important risks of surgery/ procedure. This list is NOT meant to be, and CANNOT be exhaustive.

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This brochure was developed together with NHG Eye Institute partners.

Yishun Health is a network of medical institutions and health facilities of the National Healthcare Group in the north of Singapore. It comprises Khoo Teck Puat Hospital, Yishun Community Hospital and community extensions such as Admiralty Medical Centre and Wellness Kampung. Khoo Teck Puat Hospital • (65) 6555 8000 • www.ktph.com.sg Yishun Community Hospital • (65) 6807 8800 • www.yishuncommunityhospital.com.sg