This page aims to answer some of the questions you may have about having PRESERFLO™ MicroShunt surgery. It explains the benefits, risks and alternatives of the procedure as well as what you can expect when you come to hospital. If you have any questions or concerns, please do not hesitate to speak to the eye care practitioner caring for you.

PRESERFLO™ MicroShunt surgery
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What is PRESERFLO™ MicroShunt surgery?

The PRESERFLO™ MicroShunt is a small tube about 8mm long that is inserted into the eye to help reduce the eye pressure or the need for glaucoma medications. It is made of a soft, flexible material that fits to the curve of your eye and can remain in place lifelong.

The surgeon makes an opening through the thin membrane called the conjunctiva which covers the white of your eye. A medication called Mitomycin C is applied during surgery to reduce scarring and to enhance the long term success of the operation. The use of mitomycin for this condition is unlicensed. This means although the manufacturer of the medicine has not specified it can be used in this way, there is good evidence it will be beneficial to help with healing and it has been used routinely in eye surgery for many years. The conjunctiva will be closed with stitches.There will be a small raised area under your upper eyelid that will not be noticeable unless you pull up your eyelid.The operation takes 30 to 45 minutes.
Why do I need to have PRESERFLO™ MicroShunt surgery?
Your eye surgeon has recommended the surgery because:
  • medical treatments, eye drops, or laser, have not controlled your eye pressure adequately and/or
  • you are not able to tolerate eye drop treatment
What are the benefits of having PRESERFLO™ MicroShunt surgery?
The purpose of the operation is to reduce the eye pressure, in order to preserve the sight that you have. It will not restore any sight you have already lost or improve your sight but aims to reduce the risk of further loss of vision.
What are the risks of having PRESERFLO™ MicroShunt surgery?

This type of glaucoma surgery may be preferred to other types of glaucoma surgery as there are lower chances of complications, but the following are problems that can occur after surgery:

If you have any of these symptoms, you can attend the Kersley Eye Clinic or the emergency department at your local hospital.

Are there any other alternatives??

The usual alternative to PRESERFLO™ MicroShunt surgery is an operation called Trabeculectomy. Recent research shows similar reduction of the eye pressure after surgery, but trabeculectomy is associated with a higher risk of complications than PRESERFLO™ MicroShunt and also requires more intensive follow-up. However, PRESERFLO™ MicroShunt is a newer surgery so we do not know the long term outcomes and how it compares with Trabeculectomy over a long period of time.

Will I still need to use eye drops for glaucoma after the operation?

We will usually ask you to stop all current glaucoma drops after surgery to the eye having the surgery. Some patients will be able to stay off glaucoma eye drops for many years.

Other patients, especially those needing very low eye pressures, will need to be started back on glaucoma eye drops at some point after the operation. Please continue any usual glaucoma eye drops to the eye NOT having surgery.

You will be given new drops to use for about a month in the operated eye after your surgery Details of these are given later in this leaflet.

What do I need to do to prepare for the surgery?

You will attend the day ward for approximately half a day as a day case. Sometimes you may need to stay overnight. The treatment will take place either at St Thomas’ Hospital or The London Clinic.

Will I need an anaesthetic?

The surgery can be performed under local anaesthetic (where the eye is numbed) or general anaesthetic (where you will be asleep). The type of anaesthetic used depends on the surgeon and the patient and will be discussed with you prior to your surgery.

If the surgery is performed under a local anaesthetic, you will be awake. Your eye will be numbed with eye drops and then a small injection will be given around your eye. The injection may cause a pressure sensation and brief discomfort. You should not feel any pain during the operation although you may feel a little pressure around your eye and face.The local anaesthetic takes several hours to wear off and may affect your vision during this time.

We advise that you have someone to accompany you after your surgery and you must not drive home.

If you are having a general anaesthetic or sedation, you should follow the instructions about fasting (not eating or drinking) before your operation. If you are having general anaesthetic or sedation, you will also need to have someone to accompany you home after your operation.


If you are taking any medications, these may need to be temporarily stopped or adjusted around the time of your operation or treatment. Do not make any changes to your usual medicines and continue to take them unless you have been advised to do so. Please remember to bring them into the hospital with you. 

If you are taking any medicines that thin your blood, such as antiplatelet medicines (for example aspirin or clopidogrel) or anticoagulant medicines (for examples warfarin, edoxaban or rivaroxaban), please tell your doctor or the nurse as you may need to stop or change them temporarily before your operation. Also tell your doctor or nurse if you have diabetes as you may need to alter the dose of your diabetes medicines, as if you will need to fast before the procedure. Further information on stopping any medicines will be given to you when you come for pre-assessment. 

Please ask us if you have any questions. Please let us know if you are taking any regular medicines (including anything you buy yourself over the counter or any herbal or homeopathic medicines) and if you have any allergies to any medicines.

Should I do anything special on the morning of the operation?

Advice regarding eating and drinking on the day of the surgery will be given to you before the operation. Please use your eye drops as normal on the morning of the operation unless you are told otherwise. If the surgery is under local anaesthetic then you can eat and drink as normal

Will I feel any pain?

After the anaesthetic is given you should not feel pain during the surgery. After the surgery, it is usual for your eye to be a little red and swollen and feel a little uncomfortable, gritty or light sensitive. Although uncomfortable, these symptoms are not serious, and will get better over the first few weeks.

If you have pain after the surgery you can take your usual painkillers like paracetamol or ibuprofen (unless you have been advised against using these).

You must avoid rubbing your eye at any point as this could cause problems in the eye which could potentially lead to serious complications.

What happens after the surgery?

In most cases, the surgery is done as a day case so you can go home once you have recovered sufficiently.

To protect your eye, you will have a patch and shield placed over your eye before we discharge you. This can be removed when you wake up the following day. If you have poor vision in the eye that has not been operated on, you will usually have a clear shield instead of a patch on the operated eye, so that you can still see and move around.

After the surgery, the inside of the eye is often inflamed. You will be given anti-inflammatory eye drops, usually dexamethasone to reduce this. You will also be given antibiotic eye drops to prevent infection following the surgery, usually chloramphenicol. Your doctor will give you specific instructions about how often and for how long to use these eye drops.

The eye is likely to feel uncomfortable for the first few weeks,so you can take tablets for the pain such as paracetamol, as required.Your vision will be blurred initially but should improve over a few weeks. Additionally, under the upper lid you may see a small blister-like area called a ‘bleb’ which is a result of the surgery. This is nothing to worry about.

Often the upper eyelid can be a little bit lower after surgery, sometimes giving the impression that the eye is more closed. This often improves over time. If the drooping of the eyelid affects your vision, a surgical procedure can be performed to improve the position of the upper eyelid and will be discussed at your follow up appointments.

What do I need to do after I go home?

You should continue to use the prescribed anti-inflammatory and antibiotic eye drops as directed by your doctor. Please use ONLY the eye drops that your doctor has told you to use. 

If you use glaucoma drops, you will usually stop putting them into your operated eye. If you are unsure what to do, please check with the nurse or the doctor before you leave the hospital.

If you are using glaucoma drops in the un-operated eye, please continue to use them unless clearly instructed otherwise. 

If you have been on acetazolamide tablets for eye pressure control before the operation, these should be stopped immediately after the operation.

Activity and advice following PRESERFLO™ MicroShunt surgery
Will I have a follow-up appointment?

You will be given a follow-up appointment in the clinic within a few days of your surgery so we can make sure your eye is recovering well.

It is important that you attend all planned follow-up visits after your surgery. In the initial period we need to see you quite frequently to ensure that the surgery is working well and that there are no complications. You will be given advice about the eye drops and medication you need to use at each appointment. Do check with the doctor if you are unsure about exactly what drops to use. Please bring all your eye drops and tablets with you to these appointments.

You will have to attend the clinic more frequently than usual after the surgery as the eye pressures in the first few months can be quite variable. Your doctor will decide exactly how often you need to be seen, as every patient is different.

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Kersley Eye Clinic Harley Street London

The Kersley London Eye Clinic provides Ophthalmic Services and Contact Lens in Harley Street Central London.


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Sat-Sun: Closed

42 Harley Street, London W1G 9PR, UK

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