Patient Information

Eye surgery leaflets

Colchester Eye Centre
Colchester Primary Care Centre
Tel: 07780 005 814


Preserflo microshunt


What is a Preserflo microshunt?

The Preserflo is an 8 millimetre long tube that is inserted into the eye to help lower eye pressure in glaucoma and reduce the need for medication.

It is made entirely of a synthetic and biocompatible material.

The Preserflo will not cause an allergic reaction, will not be rejected by the body and will not disappear or disintegrate with time.

As it is not metallic, it will not set off airport scanners and is safe if you need to have an MRI or CT scan.


Why do I need it?

The Preserflo is suitable for patients with uncontrolled eye pressure and with moderate-to-advance glaucoma.

The Preserflo will not cure your glaucoma, reverse any damage already caused by glaucoma, or bring back any lost vision.

It will help by decreasing the eye pressure. This will improve the control of the glaucoma and decrease the risk of further visual loss.


How does it work?

Glaucoma is most commonly associated with a build-up of fluid pressure inside the eye. This is caused by a partial blockage of the natural drainage channel of the eye. This pressure can damage the optic nerve which carries images from the eye to the brain affecting your vision. The fluid produced inside your eye is called aqueous humor.

Like glaucoma surgery, the Preserflo drains the fluid from inside the eye to the outside, under a thin skin-like membrane covering the white of the eye called the conjunctiva. The fluid is drained and pooled under the conjunctiva forming what is called a bleb.

This surgery can also be combined with cataract surgery if needed.


Is the surgery guaranteed to work?

The outcomes for the Preserflo appear to be comparative with other glaucoma surgery such as trabeculectomy.

A three year outcome study has reported a 60% fall in the eye pressure as well as a significant reduction in the number of eye drops a patient needs to take.


Are there alternatives to surgery?

There are three ways to lower the pressure inside the eye on a long-term basis:

  • eye drops
  • lasers
  • operations

You may already be using eye drops, but they may not have lowered the eye pressure enough. You may be getting side-effects or finding it difficult to use the drops.

Generally, an operation is reserved for patients for whom eye drops and lasers have not worked or are not suitable. If you do not want surgery, then your eye doctor will recommend either more eye drops to lower the pressure in your eye, or a laser procedure.


Preparing for the operation

Please continue to use your eye drops for your glaucoma as prescribed, unless otherwise directed by the eye doctor.

If you take any blood thinning medication (such as warfarin), it may need to be adjusted prior to surgery, the eye doctor will advise you.


What happens during the surgery?

The operation is performed under local anaesthetic, meaning that you will be awake but your eye will be numb so you will not feel anything.

Your eye will be numbed with eye drops before the local anaesthetic is given. Sometimes the surgery
is done under topical anaesthesia. The injection may cause a pressure sensation and brief discomfort. The local anaesthetic may take several hours to wear off and may affect your vision during this time.

A medication called mitomycin C, which is an anti-scarring medication, will be applied to enhance the long term success of the surgery.

The thin skin-like membrane covering the white of the eye (conjunctiva) will be opened and the Preserflo inserted inside your eye. The conjunctiva will be closed with one or two stitches. These stitches will be removed later in clinic.

The entire surgery is likely to take no more than 20–30 minutes.


What happens after the operation?

You can go home when you feel ready and you will need someone to take you home. The operated eye will be covered by a protective plastic shield. This can be removed the morning after surgery when you can gently bathe the eye.

You can then start the post-operative eye drops. There will be two different drops to go into the operated eye; an antibiotic for two weeks and a steroid which will be adjusted after each follow-up clinic visit.

You will usually be reviewed in the eye clinic one week after the operation and at one month.

We occasionally review on the following day depending on the severity of the glaucoma.


What about my medication?

If you are using eye drops in the other eye then you should continue to do so unless otherwise directed.

Please stop your usual glaucoma drops in the operated eye so we can assess the effect of the Preserflo.

Some drops may need to be restarted according to the pressure response to the implant.


What are the risks and possible complications?

Serious complications are rare. You could have a small amount of bleeding inside your eye. If this happens, your vision could be blurred for one to two weeks or occasionally longer.

Like any other glaucoma surgery, the eye pressure lowering effect of the Preserflo may wear off with time. This is most often due to scarring around the Preserflo. If this happens, you will need to restart your glaucoma drops or have further procedures to control your eye pressure.

There is probably a very small life-long risk of infection after the Preserflo operation due to the creation of the bleb.

There is also a small risk that the shunt might become exposed and need to be repaired. The risk of very low pressure after the operation is much less than with a trabeculetomy and persistent very low pressure is rare.


Post-operative instructions

  • Do not rub or press on the eye after the operation. As this can happen when you are sleeping we will ask you to continue wearing the plastic shield at night for a few weeks.
  • Reading, watching television and using the computer are fine.
  • Do not drive until the doctor tells you it is OK to do so.
  • Most people need 1–2 weeks off work after the operation.
  • Keep the eye dry for two weeks. This is to reduce the risk of infection.
  • Please ensure you wear goggles when swimming.
  • It is safe to fly after the operation. However, you will need to be seen a number of times by the eye doctor in the first three months.


Contact us

Please ring the Eye Clinic on 01206 286 882 if you have any problems or concerns.
The Eye Clinic is available:
Monday to Friday, 8am to 7pm
Weekends and bank holidays 11am to 4pm

Outside these times please contact your GP.

In an emergency either telephone 111 or visit the NHS 111 website, go to an urgent treatment centre or your nearest emergency department (A&E).


Your experience matters

We value your feedback. Please help us improve our services by answering a simple question, in our online survey – “Overall, how was your experience of our services?”
This survey is known as The Friends and Family Test.




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