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Bleb needling

Understanding the procedure and what to expect.

Bleb needling is a procedure which is sometimes needed by people who have previously had glaucoma surgery.

With certain forms of glaucoma surgery, fluid from the inside of the eye drains into a space that is covered by the conjunctiva, which is the superficial layer on the white of the eye. This drainage area is known as a “bleb” and is usually hidden by the upper eyelid.

Sometimes excessive scar tissue can form inside the bleb. Scar tissue reduces the amount of fluid draining from the eye and causes the eye pressure to increase. This can happen either soon after glaucoma surgery, or months or years later.

The types of glaucoma surgery which lead to the creation of a bleb and may require needling are usually a trabeculectomy operation, or sometimes a Preserflo microshunt or tube shunt surgery.

  • With trabeculectomy surgery fluid drains into the bleb through a trapdoor-like opening, which is made in the white of your eye.
  • With the Preserflo microshunt fluid drains into the bleb through a small implant. 
  • With tube shunt surgery a drainage area (also called a bleb) is formed around the plate, which is the wide part of the tube secured at the back of the eye. Sometimes excessive scar tissue can form inside this space, which reduces the amount of fluid drained by the tube. 

Why is Bleb needling required?

A bleb needling is performed to address scarring that has occurred in the bleb. It aims to restore the amount of fluid draining from the eye to reduce the eye pressure, which in turn will reduce the chance of irreversible damage to the vision from glaucoma. 

What does the procedure involve?

A bleb needling can be performed in the clinic or as a day case procedure in the operating theatre, which means you can go home on the same day. Although the procedure is essentially the same, there are pros and cons with having the needling in clinic versus in the operating theatre. For example, needling in clinic can be done then and there at the slit-lamp, but requires a good level of patient co-operation. Needling in theatre may be more comfortable for the patient, but requires scheduling. Further details should be discussed with your specialist.

Before the procedure, you will have eye drops to numb the eye. An injection of local anaesthetic may also be given around the eye.

Needling involves the careful use of a fine needle to break up scar tissue around your bleb to restore fluid flow. Sometimes, anti-scarring agents (such as Mitomycin C, 5 Fluorouracil and/or Bevacizumab) may be used to reduce the risk of scarring later. 

What is the success rate of bleb needling?

The success of your bleb needling procedure depends on multiple factors which you should discuss with your specialist. On average, bleb needling is successful in 50% of patients at 1 year, and in 15% of patients at 2 years following the procedure. However, individual success rates can vary a lot from one patient to the other. If needling is successful, then you may be able to avoid or push back a bigger glaucoma operation and the associated risks.  

What are the risks of bleb needling?

As with any surgical procedure, bleb needling carries some risks, including:

  • Inflammation – you will be given steroid drops to be used after the procedure.
  • Pain - you might feel some discomfort after the procedure which is usually mild and short-lasting. Paracetamol can be taken if needed.
  • Failure to reduce the eye pressure - Bleb needling may fail to initially lower the eye pressure or may be successful for a period of time and then fail.  Bleb needling is sometimes repeated to increase the period of successful eye pressure lowering.
  • Eye pressure that is too low - This is usually temporary but if persistent it may require further intervention to address the low pressure. This may include an injection into the front chamber of the eye in the clinic, or a surgical procedure in the operating theatre.
  • Irritation to the clear window of the eye (the cornea) that can be caused by the anti-scarring agent – this usually resolves fully.
  • A serious infection of the eye which can lead to loss of vision – this is very uncommon (1 in 1000 or less).
  • A significant bleed in the eye which can cause loss of vision – this is very uncommon (1 in 1000 or less).
  • The overall risk of losing vision because of bleb needling is very small (1 in 1000 or less).

Will bleb needling improve my vision?    

The purpose of this procedure is not to improve your vision but to reduce the eye pressure, in order to help preserve the vision you currently have.

Are there other treatment options?

The main alternative options are to continue on drops to lower the eye pressure or proceed to an alternative procedure, such as laser or tube surgery (in those with previous tube surgery, a second tube may need to be considered). The success rate of each alternative option depends on various factors, so you will need to discuss this with your clinician. 

Before and after the procedure

You should continue all your glaucoma medications until the day of procedure. Let us know if you are taking any blood thinners. If a preoperative assessment is required, we will let you know.

Your vision may be temporarily affected after the procedure. If the procedure is done in the operating theatre, you will go home with a plastic shield covering the eye. Our nursing team will provide you with instructions on how to use the drops post-surgery.

The next morning, remove the shield and if required gently clean your eyelashes with cooled, boiled water. Start your prescribed eye drops. Do not rub or press on the eye. Continue to wear the shield when sleeping to protect the eye, until your doctor advises you that you can stop.

You must continue your usual drops to the other eye, if you are taking any. You will have multiple clinic appointments after the procedure to monitor your eye pressure and healing process.

Most patients require at least one week off work, but if you work in a dirty environment or perform manual work you may require more time off.

If you experience any problems postoperatively, you can always contact the Moorfields Direct telephone helpline at 020 7566 2345.

When to contact the hospital?

If you experience increasing pain, redness, worsening vision or green or yellow sticky discharge, please go straight to your local accident and emergency department, or the accident and emergency department at Moorfields Eye Hospital, 162 City Road, EC1V 2PD, which is open 24 hours, 7 days a week.

Author:  Panagiota Founti
Review date: October 2028

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