Trabeculectomy + Mitomycin C (anti-scarring agent)/ Conventional Glaucoma surgery



This operation is called a trabeculectomy (trab-ec-u-lec-tomy). This is recommended for patients whose glaucoma continues to progress despite using eye drops and/or having had laser treatment. The goal of trabeculectomy surgery is to help lower and control your eye pressure. This eye pressure is known as intra-ocular pressure (IOP). If your IOP remains high, then further irreversible loss of vision and visual field may occur from glaucoma. This operation will not improve your vision or cure glaucoma, but aims to or slow down further visual loss from glaucoma damage. The goal is to reduce your risk of blindness from glaucoma in your life time.

What is a Trabeculectomy?

A trabeculectomy is an operation to create an alternative drainage channel, to help aqueous fluid (natural fluid of the eye) drain from your eye. This operation creates a controlled surgical bypass for the blocked natural drain (trabecular meshwork) of your eye. Your eye pressure is reduced because fluid can now drain with relative ease through the newly created drainage channel. This is aimed at better control of eye pressure and glaucoma but not to improve vision.

Vision once lost from glaucoma can not be regained. All treatment/operation for glaucoma is aimed at slowing down the rate of progression of glaucoma so that the risk of complete blindness in one's lifetime may be reduced.

How is a trabeculectomy operation performed?

During this operation a tiny opening is made in the white of your eye (sclera), underneath the top eyelid, to form a new drainage channel. This allows the eye fluid to drain through the opening into a reservoir called a ‘bleb’ and then to be absorbed by the body. The bleb is underneath the conjunctiva (thin transparent layer covering the sclera) on the surface of your eye, underneath the top eyelid. Trabeculectomy surgery can be carried out under either a local anaesthetic or a general anaesthetic which will be discussed with you whilst listing you for surgery. 

How successful is trabeculectomy surgery at lowering intra-ocular pressure (IOP)?

Audits and studies on the success of trabeculectomy surgery show it is dependent upon many variable factors. Factors that can reduce the success of trabeculectomy surgery are: Younger age, Race (Asian, Afro-Caribbean), Uveitis (inflammation within the eye), Very high pressure in eye, Previously failed glaucoma procedure, Previous eye surgery, Previous severe eye injury, Rubeotic glaucoma where there are abnormal blood vessels on the iris, Excessive natural healing process and Diabetes.

Where the success of Trabeculectomy surgery is based upon a patient’s IOP being less than 21mmHg a year after surgery: The national average is that 66% of patients achieve this. (The National Survey of Trabeculectomy, UK. 1999; (Edmunds et al). Some patients (about 1/3^rd) may need to return to use one or more glaucoma eye drops to maintain a satisfactory eye pressure. Eye eye pressure is expected to be controlled for 5-7 years ('Shelf Life') after a trabeculectomy operation. Further surgical or laser procedures may be required if trabeculectomy surgery fails.

Are there any risks associated with trabeculectomy surgery?

As with any surgery, there is the potential for complications or problems to arise. Complications can occur during surgery, shortly after surgery or many months after surgery.

Complications that can occur:

·       Bleeding is a serious but uncommon complication from this surgery. This can lead to loss of vision and even blindness but occurs very rarely.

·       An infection inside the eye can be very serious and also cause loss of vision or blindness. This is also quite uncommon (approximately 1.5%).

·       After the operation the eye pressure may be too high or too low. This may require additional treatment or adjustments in the glaucoma clinic or sometimes further surgery. Extra stitches may have to be put in operating theatre if the eye pressure was too low (about 1 in 10 cases).

·       The eye may be inflamed for prolonged period after surgery.

·       Swelling in the retina can affect your vision but this is mostly treatable.

·       Some eyes with very advanced glaucoma may experience complete loss of vision/visual field called ‘wipe out’ phenomenon, this is quite rare(1/20 cases). 

·       There are also the very uncommon risk factors from local or general anaesthesia.

Some patients are aware of the drainage bleb under their upper eyelid or that there is slight drooping of the eyelid but this usually settles down. As your eye settles down and heals you may need a change of glasses, to get your best vision. About 10% of patients’ notice that their vision is reduced by one line on the eye chart a year after the operation, as cataract formation may be increased by trabeculectomy surgery.

The use of Mitomycin C (= antimetabolites=anti-scarring drugs)

The main reason trabeculectomy surgery can fail is that the newly created drainage site can scar and heal up by your own body’s natural tendency to heal. The previous mentioned risk factors can predispose to this.

Antimetabolites are medications that prevent scar tissue formation. If we are concerned that excess scarring may occur then the use of these medications can limit this process and enhance the success rate of the operation. The most commonly used antimetabolites are Mitomycin C (MMC) and 5 Fluorouracil (5FU) and these can be used at the time of surgery or afterwards.

Before your operation

You should continue any eye drops and tablets for your glaucoma as prescribed, until the time of your surgery, unless directed otherwise specifically. You will be asked to use a new eye drop four times a day to the listed eye for four weeks leading to the operation. If you are taking any blood thinning tablets (Warfarin or Aspirin), they might increase risk of bleeding during the operation. It might be advisable to stop them for a very short period before surgery provided this does not affect your general health. Please discuss this with the glaucoma team.

After your operation

Immediately after your operation, your eye will be covered by an eye pad and protective plastic shield. Eye drops are not usually required in your operated eye until the day after surgery. Any eye drops that you use in your other eye must be continued as normal. The morning after your operation the eye pad and protective eye shield will be removed. Your eye will be cleaned and examined and eye drops commenced. The eye drops you will need to use in your operated eye will be different from the drops that you used prior to your operation.      

Drops will need to be used for approximately 3 months after your operation. Each time you attend the glaucoma clinic any changes to your eye drops will be discussed with you. If you are running out of the drops you must obtain a repeat prescription for them from your own GP.

Post operative visits

The success of trabeculectomy surgery depends upon the rate and extent of the conjunctival healing process. Your IOP can fluctuate widely in the first few weeks after surgery. During the first few weeks you will need to attend the out patients clinic frequently for close monitoring. The 1st visit is usually the next day, the 2nd visit is a week later and subsequent visits are arranged based on individual patient's circumstances. There are many adjustments that may need to be made, during your clinic visits, to maximise the success of your surgery. Such as, changes to eye drop medications, adjustments to or removal of stitches and possibly having anti-scarring injections. It is very important that you attend all your clinic appointments with Mr Raj and use your eye drops as prescribed. It is advisable not to be away or outside the country during these critical 3 months after surgery.

You may find further information on ocular hypertension (raised pressure in the eye but without glaucoma) and glaucoma, on risk of blindness from glaucoma and various management options in some of the following websites.

http://en.wikipedia.org/wiki/Trabeculectomy

http://emedicine.medscape.com/article/1844332-overview

http://www.glaucoma-association.com/

http://www.glaucoma-association.com/the-eye-and-glaucoma/what-is-glaucoma-.html

http://www.glaucoma-association.com/blog/brits-urged-to-take-their-eye-health-seriously.html

http://www.nei.nih.gov/health/glaucoma/glaucoma_facts.asp

http://www.rnib.org.uk/eyehealth/eyeconditions/eyeconditionsdn/Pages/glaucoma.aspx

http://en.wikipedia.org/wiki/Glaucoma

http://guidance.nice.org.uk/CG85/NICEGuidance/pdf/English

http://www.rcophth.ac.uk/page.asp?section=365&sectionTitle=Information+

The information in this booklet is provided for information only. The information found is NOT a substitute for professional medical advice or care by a qualified doctor or other health care professional. ALWAYS check with your doctor if you have any concerns about your condition or treatment. This is only indicative and general information for the procedure. Individual experiences may vary and all the points may not apply to all patients at all times. Please discuss your individual circumstances with your eye doctor.

Links To Third-party Sites

Mr Raj does not control such Websites and is not responsible for their contents. The inclusion of links to such Websites does not imply any endorsement and exclusion of other websites does not mean any negative endorsement of the material on such Websites or any association with their operators. Mr Raj does not monitor or warrant their content and makes no warranty about and accepts no liability for third party content.

Always discuss with your doctor if you have any doubt or concern about any part of the information in this booklet.

If you have any of the following after a trabeculectomy surgery:

·       Sudden loss of vision

·       Severe and unrelenting pain

·       Any abnormal and increasing discharges

Please contact your local eye unit emergency service team.