What is a PreserFlo Microshunt?
The MicroShunt is an 8-millimeter-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.
It creates an escape tunnel for any excess fluid from inside the eye to safely drain into a small blister, or filtering bleb, behind the eyelid. From there, the fluid is slowly absorbed into the bloodstream.
The MicroShunt will not cause a reaction or be rejected by the body. It is meant to be permanent. 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 MicroShunt is suitable for patients with uncontrolled eye pressure and its pressure-lowering effect is generally superior to other implants. It may be as effective as a trabeculectomy and it is therefore potentially suitable for moderate-to-advanced glaucoma.
The MicroShunt will not cure your glaucoma, reverse any damage already caused by glaucoma, or bring back any lost vision, but by decreasing the eye pressure, it can help to prevent further vision loss.
How does it work?
Glaucoma is most commonly associated with a build-up of fluid pressure inside the eye. This build-up of fluid pressure is caused by 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 PreserFlo MicroShunt drains fluid from inside the eye to outside and pooled under conjunctiva forming what is called a bleb. Your eye surgeon may combine this operation with a cataract operation.
Please see the cataract surgery leaflet for further information.
Is the surgery guaranteed to work?
Studies have shown a 60% fall in the eye pressure as well as a significant reduction in the number of eye drops a patients needs to take.
We currently do not have long-term studies on the device.
Are there alternatives to surgery?
There are three ways to lower the pressure inside the eye on a long-term basis: eye drops, lasers and operations. You may already be using eye drops, but they did not lower the eye pressure enough, you are getting side-effects, or you find it difficult to use the drops. Generally, an operation is reserved for patients in whom eye drops and lasers have not worked or are not suitable.
What if I don’t want surgery?
Then your eye surgeon 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 any eye drops and tablets for your glaucoma as prescribed, unless directed otherwise by your ophthalmologist.
If you take any blood-thinning medication (e.g. Warfarin, Aspirin) or have had bleeding problems in the past please discuss this with your ophthalmologist prior to surgery.
Prior to the operation, you will be asked to attend a pre-operative assessment appointment to check you are fit for the procedure and anaesthetic.
What happens at the time of surgery?
The operation is usually performed under a local anaesthetic, meaning that you are awake but your eye is numb so you will not feel anything. 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 will have the option of requesting sedation or a general anaesthetic so you are fully asleep during the operation.
The local anaesthetic takes several hours to wear off and may affect your vision during this time. A medication called Mitomycin C will be applied to enhance the long term success of the surgery.
The conjunctiva (covering of the white part of the eye) will be opened and the MicroShunt is inserted inside your eye.
The conjunctiva will be closed with one or two stitches. These stitches may either be removed later in clinic or, in some cases, dissolve by themselves.
The entire surgery is likely to take 30 minutes.
What happens after the operation?
You can go home after the surgery.
The operated eye will be covered by a protective plastic shield which you can remove the morning after surgery. Do not worry about instilling any drops in the eye until after the shield has been removed. The morning after your operation you can remove the shield and gently clean the eye. You can then start the post-operative drops. You will usually be reviewed in the eye clinic one week after the operation and at 2 weeks.
We occasionally review on the following day depending on the severity of the glaucoma.
What about my medication?
If you are using drops in the other eye you should continue to do so unless directed otherwise.
Please stop your normal glaucoma drops in the operated eye so we can assess the effect of the PreserFlo MicroShunt (some drops may need to be restarted according to the pressure response to the implant).
There will be two different drops to go in the operated eye-an antibiotic and a steroid which need to be continued for approximately 3 months post-surgery.
What are the risks and possible complications of surgery?
Serious complications are rare. You could have a small amount of bleeding or inflammation inside your eye. If this happens, your vision could be blurred for one to two weeks or occasionally longer.
Like all glaucoma surgery, the eye pressure-lowering effect of the MicroShunt may wear off with time. This is most often due to scarring around the MicroShunt. If this happens, you will need to restart your glaucoma medications or have further procedures to control your eye pressure, which would usually be another aqueous shunt (Baerveldt, Ahmed or Paul Glaucoma implant).
There is probably a very small life-long risk of infection after MicroShunt surgery due to the creation of a bleb, which in very rare cases may cause blindness.
There is also a small risk that the shunt might expose and need to be repaired. There is a risk of very low pressure after surgery, and persistent very low pressure is rare.
5 in 100 may require taken back to theatre for tube blockage
Post-operative Instructions
No rubbing or pressing on the eye after surgery. As this may happen when you are sleeping, we advise you to continue to wear the plastic shield at night for the first two weeks after surgery. Reading, TV & using the computer are fine. Do not drive until your surgeon says it is OK to do so. Most people need 1-2 weeks off work after surgery. Keep the eye dry for 2 weeks. This is to reduce the chance of infection. Do not swim after surgery. It is safe to fly after the surgery, however, you will need to be seen a number of times by your surgeon in the first 3 months.