Preserflo Microshunt

What is a Preserflo Microshunt?

This is a small 8.5mm length implant that is as thick as a human hair. It is made from an inert polymer material. This operation involves cutting through the surface tissue (conjunctiva) of the eye and inserting the implant through the white outer shell of the eye (sclera) and into the front compartment. The implant sits in the front compartment of the eye and extends to the space under the conjunctiva (bleb) to drain fluid out from the eye.

Mitomycin-C is applied to the operation site to reduce scarring and increase the success rate of the operation.

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Why do I need this procedure?

The main purpose of the Preserflo Microshunt is to lower eye pressure. The Preseflo Microshunt will help to prevent further loss of vision by reducing your eye pressure. However, it will not cure your glaucoma nor reverse any damaged vision from glaucoma. You may have been advised to undergo this procedure if your eye pressure is uncontrolled by glaucoma eye drops or to prevent progression of your glaucoma.

What are the preparations?

Please remember to fast at the time that you have been instructed to. You will be asked to arrive about 2 hours before your scheduled time for surgery. This is to allow eyedrops to be instilled into your eye to facilitate the operation. Continue your glaucoma medications up to the day of surgery. If you are on blood thinning medications, you will have to stop these prior to surgery as advised by the doctor.

How is the procedure performed?

Your operation will last between 60 to 90 minutes. You will be given either a local or a general anaesthetic to control pain. You may be able to feel the surgeon’s hand resting on your forehead but you should not feel any pain. If you do feel pain, please let the surgeon know. Try not to talk or move in order to minimise complications.

What are the chances of success for this surgery?

Your glaucoma specialist is the best person to give you an idea of the success rate. This may vary from 60 - 90%, depending on the patient, and the severity and type of glaucoma. The aim of surgical treatment is to reduce eye pressure. A secondary aim is to wean off glaucoma eyedrops. It is important for you to understand that the main aim of eye pressure reduction is to preserve remaining nerve fibres and prevent further nerve damage. Occasionally, the operation may not work as well as intended due to various factors.

In these cases, glaucoma eyedrops may have to be re-started in order to control the eye pressure adequately. Do remember that in glaucoma surgery, success means good eye pressure control without further visual loss, not improvement in vision.

What are the risks and complications of the procedure?

Mild

1. Transient blurring of vision: This is often temporary and resolves after about a month

2. Redness and discomfort: These are transient and resolve after a few weeks

3. Low eye pressure: Occasionally, the eye pressure can be low for a few days to a few weeks and this can induce swelling at the back of the eye which can impair vision. These usually resolve after some time

4. Cataract formation: If you have your natural lens left in place during the surgery, there is a chance that you will develop a cataract at an accelerated rate

5. Droopy eyelid: Occasionally, following the procedure, it is possible to have drooping of the upper eyelid. This may require another separate operation to restore normal lid position

6. High eye pressure: The eye pressure can be high for days to weeks or even months following the surgery. This is because the Preserflo is blocked. A minor procedure (bleb needling) can be performed to remove the blockage using a fine needle to sweep underneath the conjunctiva. An anti-scarring medication (Mitomycin C or Fluorouracil) may be injected around the bleb during time of needling

Severe

1. Infection (1 in 1000-2000 chance following surgery)

2. Severe sight-threatening bleeding: Occurring with the eye (1 in 1000-2000 chance) at the time of surgery or soon after

3. Severely low eye pressure: In some very rare instances, if the eye pressure drops too low after surgery and vision is affected, a second operation may be needed to tighten up the artificial channel and adjust the eye pressure

4. Loss of the central visual field: Rarely, in older patients with advanced damage due to glaucoma, central vision may be permanently lost suddenly after surgery

5. Implant-related: Rarely, the implant may be malpositioned or exposed from under the conjunctiva. Further surgery may be required to reposition the implant. If the implant is blocked and bleb needling is ineffective, surgery may be required to remove the blockage

6. Bleb-related:

• Dysesthesia “abnormal sensation”

The size, location and appearance of the bleb can cause discomfort immediately after surgery or even months later. Typically, larger sized blebs and those that are not covered by the eyelids (hanging/nasal/temporally located blebs) has an increased risk of causing discomfort. This is due to disruption of the tear-film layer over the surface of the eye and interference with eyelid closure. Treatment with lubricants will suffice in most cases, with the rare few requiring bleb modification with laser or surgery.

• Leak In some instances, the area of fluid space under the conjunctiva (bleb) may leak, which will result in low eye pressure. Treatment with medicated eyedrops or, rarely, surgery is required to prevent infection or implant extrusion.

• Infection Rarely, an infection localised to the bleb may spread into the eye and will require urgent treatment.

7. Like any glaucoma surgery, the eye pressure lowering effect of the surgery may wear off with time and glaucoma eyedrops may need to be re-started. Failing which a repeat glaucoma surgery may be performed.

Rare Risks of Anaesthesia:

1. General Anaesthesia:

• Risks of myocardial infarction (heart attack)

• Risks of cerebrovascular accident (stroke)

2. Regional Anaesthesia

• Risks of piercing the eyeball

• Risks of severe bleeding

• Risks of diplopia (double vision)

What can I expect after the procedure?

1. Sensations: It is normal to feel some discomfort and mild pain after surgery due to the presence of some stitches. However, this should very quickly subside but in some cases, it may persist for up to 4 weeks. You may also have some tearing and be sensitive to light for a short time. Care should be taken to avoid rubbing the eye.

2. Vision: Your vision may be blurred for the first few days and there may be slight redness or swelling. This will gradually disappear.

3. Medications: You will need to apply eye drops diligently, to aid healing and prevent infection following surgery, and any other medicines that your doctor may prescribe. These will be tapered off over three to six months.

4. Precautions: The eye should not be rubbed during the first few weeks after surgery. You may be asked to wear a shield over the operated eye, particularly while sleeping. For the first few weeks, be careful not to get any water, face cream, soap or shampoo into the operated eye.

5. Follow-up visits: You can expect to be followed-up closely for the first 3 weeks. In the following 6 months, you may also be required to undergo a series of injections to the surface of your eye, in order to facilitate the success of your operation. These will be done during your regular visits to the eye clinic and do not require any preparation on your part.

6. Activities: You may resume most normal activities after 1-2 weeks following surgery. Activities such as reading, watching television and cooking will not hurt the operated eye. Try to avoid bending at the waist or heavy lifting for 3-4 weeks after surgery. Light exercise like walking is allowed 6 weeks after the surgery. Swimming is prohibited.

7. Diet: There are no special dietary restrictions following surgery.

What are the other options?

The alternative to the Preserflo Microshunt would be conventional glaucoma drainage surgery (trabeculectomy) or Glaucoma Drainage Device (Tube) Surgery. These options albeit effective are more invasive in nature and carries potentially higher risks with longer visual recovery. Laser procedures for glaucoma may be performed, which may not be as effective as surgery.

What will happen if I do not undergo the procedure?

There is a risk of progressive vision loss or blindness if your eye pressure is not controlled.

DISCLAIMER: This information sheet mentions some of the more common or important risks of surgery/ procedure. This list is NOT meant to be, and CANNOT be exhaustive.

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This brochure was developed together with NHG Eye Institute partners.

Yishun Health is a network of medical institutions and health facilities of the National Healthcare Group in the north of Singapore. It comprises Khoo Teck Puat Hospital, Yishun Community Hospital and community extensions such as Admiralty Medical Centre and Wellness Kampung. Khoo Teck Puat Hospital • (65) 6555 8000 • www.ktph.com.sg Yishun Community Hospital • (65) 6807 8800 • www.yishuncommunityhospital.com.sg

The information is correct at the time of printing and subject to revision without further notice.