Trabeculectomy

Trabeculectomy is performed to reduce the pressure within the eyes (intraocular pressure [IOP]) in individuals with uncontrolled glaucoma.

Glaucoma comprises a group of diseases of the eye that damage the optic nerve (the nerve that carries signals from the eye to the brain) and may cause blindness. High IOP in the eye is among the common risk factors of glaucoma. The IOP increases when the tiny drainage canals in the eye called the trabecular meshwork are blocked. The trabecular meshwork is present in the drainage angle of the eye, between the iris (the coloured part of your eye) and the cornea (the transparent covering of the eye) and is responsible for the drainage of aqueous humour, the fluid inside the eye.

A surgeon may recommend this surgery if you have glaucoma, and treatment with eye drops fails to keep your IOP under control. There are no symptoms during the initial stage of glaucoma; however, as it progresses, loss of peripheral or side vision is observed. Most individuals identify this when glaucoma has progressed to an advanced stage. Other eye symptoms associated with glaucoma are:

• Redness in eye
• Eye pain 
• Hazy vision in one or both eyes
• Narrowing of vision
• Seeing bright circles around light sources

This surgery may not be recommended in individuals with the following conditions:

• Glaucoma present since birth
• Diabetes
• Formation of new blood vessels on the iris that makes glaucoma difficult to manage
• A previous eye surgery

You can expect the following as part of the pre-operative preparations:

• The eye surgeon will ask a few questions regarding your health.
• The surgeon may also take the measurements of your eye and order blood tests and an electrocardiogram (recording of the heartbeat) to ensure you are healthy enough for the surgery.
• You will be asked about all the medicines that you take and about substances (especially surgery-related items such as adhesive tapes and dressings) that you are allergic to.
• The surgeon may ask you to discontinue or alter the dosage of a few medications. For example, you may need to temporarily stop taking blood-thinning medicines such as aspirin; or the dosage of your diabetes medications may need to be altered if fasting is required before surgery.
• You will be asked to sign a consent form giving your approval for the procedure.

You need to take care of the following before going to the hospital on the day of the surgery:

• Avoid wearing any jewellery, nail varnish, and makeup as you will need to remove them before the procedure.
• If the surgeon has advised any dietary restrictions on the day of the surgery, follow them accordingly. If no such restrictions have been suggested, you can drink and eat normally.
• Bring all your regular medicines, including inhalers and eye drops, to the hospital.
• Carry clean, comfortable clothes and a pair of slippers, in case the surgeon wants you to stay at the hospital overnight for observation.
• You may also need to ask a family member or friend to drive you home after the surgery.

This surgery is performed under general anaesthesia (medicines that make you fall asleep) or local anaesthesia (medicines that numb a specific part of the body). The procedure usually involves the following steps:

• You will be given local or general anaesthesia by an anesthesiologist. Depending on the anaesthesia, you will either be awake or asleep during the procedure.
• A surgeon will clean your eye (the one that needs to be operated) and place a device called a lid speculum on the affected eye to keep it open during the procedure.
• The surgeon will then remove a small piece of tissue from the drainage angle under your upper eyelid to create an opening. The opening created is such that it is partly covered by a flap created from the tissue of the sclera (the white part of the eye). As the aqueous humour drains out through the new opening, the flap tissue rises to form a bubble. This bubble is called a bleb, which is used by doctors to check drainage from the new opening during follow-up visits.
• The surgeon will stitch the flap over the bleb such that the new opening does not close or reseal during the recovery period. The placement of stitches also decides the amount of aqueous humour that should drain from the new opening. The stitches will be removed in about two weeks after the surgery.
• Finally, the surgeon will apply antibiotics in the operated eye and shuts it tight with tape.
• After the procedure, the operated eye will be covered with an eye patch or shield.

The surgery takes about an hour to complete. Mostly, you will be discharged on the same day. However, in some cases, the surgeon may ask you to stay overnight in the hospital.

It is normal to experience blurred vision and discomfort in the eye after a trabeculectomy. It may take about two months for you to recover your normal sight. You need to take care of the following during the recovery period:

• Your eyes will be swollen after the surgery. The surgeon will prescribe anti-inflammatory eye drops for the same. Use them as directed.
• You will also have to use antibiotic drops to prevent infections in the eye.
• Before cleaning your eyes or putting eye drops, it is essential that you wash your hands thoroughly.
• It is normal to experience sticky eyes when you wake up in the morning. Clean your eyelids gently using water that has been boiled and cooled.
• Avoid rubbing your eyes after surgery. The surgeon will ask you to wear a plastic shield over the eyes to prevent you from rubbing them accidentally during sleep. Wash and clean the plastic shield before every use. You can also wear the shield during the daytime.
• Discontinue the use of glaucoma eye drops and medicines like acetazolamide (a medication for controlling IOP) immediately after surgery.
• Avoid swimming, contact sports, strenuous activities, and activities that require bending during the first two weeks following surgery. You can, however, watch television and read.
• You can bathe or shower normally.
• Inform your eye doctor before travelling out of the country. It is recommended to get your eye checked before such travels. You will also need to carry an adequate supply of eye drops.
• The time required away from work depends on the nature of your work and your vision in the other eye. It is usually advisable to rest for at least two weeks after the surgery. This time may increase if your job requires heavy labour.
• You will need to consult your eye doctor before resuming driving. 

Trabeculectomy helps to lower increased IOP. However, the surgery does not restore any vision loss caused due to glaucoma but merely prevents further damage to the eye.

When to see the doctor?

Contact your doctor immediately if you have any of the following symptoms after surgery:

• Loss of vision
• Excessive pain
• Sticky discharge from the eye
• Increased redness in the eye

Scarring generally occurs after trabeculectomy and can interfere with the functioning of the new surgical opening. If the opening does not work properly, you may need another surgery. Hence, the surgeon will prescribe medicines after surgery to prevent scarring. Other ocular complications that could develop within a few days of surgery are:

• Bleeding
• Infection
• Sudden and permanent loss of vision
• Blurred vision
• Increase in IOP

Some complications do not develop immediately after surgery but may develop after a few days of the procedure. These include:

• Infection
• Droopy eyelid
• Continous damage to optic nerves even after the procedure
• Blurred vision, which is in a worse condition than usual

You will need to visit the hospital a day after the surgery to get IOP and bleb checked and to get the eyepatch removed.

You may need to visit the hospital frequently during the first month after surgery to ensure there are no complications. Further visits, if required, will be decided by the eye surgeon. 

Disclaimer: The above information is provided purely from an educational point of view and is in no way a substitute for medical advice by a qualified doctor.