Glaucoma is a chronic and lifelong disease which results in reduced vision if left untreated. This is as a result of damage to the optic nerve at the back of the eye, due to an excessively high pressure of the fluid inside the eye. In all cases of glaucoma, the aim is to reduce the pressure inside the eye to a level which prevents any further deterioration of the optic nerve. This is most commonly achieved by using eye drops on a daily basis. However, for some people, the drops do not stop the progression of the glaucoma and so surgery is needed to lower the pressure further. The surgery is called a trabeculectomy operation.

A trabeculectomy allows the fluid inside the eye to leave more quickly than before the operation. This is done by creating a tiny flap in the white of the eye, at the top of the eye and beneath the upper eyelid. The flap is secured with stitches that can be released after the operation, allowing the pressure in the eye to be adjusted after the operation. The white of the eye is covered by a transparent membrane, the conjunctiva and this covers the flap after the operation. The aim of the operation is to allow the fluid from the eye to leave more quickly but not to leak out onto the surface of the eye (otherwise there would be a route for infection to travel into the eye).


The operation can be carried out under a local anaesthetic or if required a general anaesthetic. It is important to monitor the pressure closely after the operation as the stitches securing the pressure controlling flap may need to be released to lower the pressure further. This results in several visits to the clinic after the operation, within the first two months after surgery. It is also important to use antibiotic drops after the operation as instructed.

In some cases the pressure is low enough that no further glaucoma medications are needed. In other cases the number of drops can be reduced as the new pressure, after the operation, is considerably lower.

Complications from trabeculectomy surgery can occur. Bruising and redness are common after surgery but settle after 1-2 weeks. The eye may feel gritty during this period as well. Occasionally the new drainage site, underneath the upper eyelid, can cause some persistent irritation but lubricating drops should settle this problem.

Rare but serious complications of trabeculectomy surgery include visual field ‘wipe out’. This can happen in patients with very poor vision at the time of trabeculectomy surgery whereby the remaining vision is severely affected after the surgery. This very uncommon complication can take away the little remaining vision in the eye. Other serious complications include a bleed starting at the back of the eye during surgery, which can result in poor vision after the operation and endophthalmitis or an infection which gets into the eye and can cause significant damage to the eye with subsequent reduced vision.

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Surrey Eye Surgeons

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