In short: the PreserFlo MicroShunt (Santen) is an 8.5 mm soft polymer tube placed through the wall of the eye to drain fluid into a small reservoir (bleb) under the lining of the eye, lowering pressure into the mid-teens or below. It suits moderate-to-advanced open-angle glaucoma that needs more pressure reduction than keyhole MIGS can give, and its built-in flow resistance means fewer early complications than a traditional trabeculectomy.
What is the PreserFlo MicroShunt?
When glaucoma is progressing despite maximum drops and laser — or when the optic nerve needs a low target pressure in the mid-teens or below — keyhole MIGS devices may not lower pressure far enough. Filtration surgery creates a new drainage route instead.
The PreserFlo MicroShunt is a 8.5 mm tube made from SIBS, a soft, biostable medical polymer, with a precise 70-micrometre internal channel. It is inserted from the outside of the eye through a tiny scleral tunnel; fluid drains through it into a low, diffuse bleb under the conjunctiva. The narrow channel gives a defined opening pressure of around 6 mmHg, which protects against the very low pressures (hypotony) that can complicate trabeculectomy. In the pivotal INN-005 trial it produced a mean pressure of around 13–15 mmHg at one year with materially fewer post-operative interventions than trabeculectomy.
Your options
Your consultant will recommend the approach that matches your target pressure, the stage of your glaucoma and whether you also have a cataract.
Not sure whether you need filtration surgery or keyhole MIGS? A consultant assessment makes it clear.
Book your assessmentHow the procedure works
PreserFlo is implanted “ab externo” — from the outside of the eye — as a day case under a local anaesthetic block, so you are awake but feel no pain.
Before — assessment
Your consultant confirms progressing open-angle glaucoma with pressure checks, gonioscopy, OCT of the optic nerve and visual fields, and sets your target pressure. Healthy conjunctiva is needed for the bleb to work.
In theatre — 25–40 minutes
A small flap of the eye’s surface lining is lifted, an anti-scarring agent (mitomycin-C) is applied, and the MicroShunt is tunnelled through the sclera into the front of the eye. The lining is closed water-tight over a low bleb.
Same day — home
You go home the same day with a shield and a course of antibiotic and anti-inflammatory drops. No overnight stay; arrange someone to drive you home.
Recovery
You’ll use drops for around six to eight weeks while the bleb settles, and attend a structured set of reviews over the first 12 weeks (typically six to eight visits). Some eyes need a quick “needling” at the slit lamp to keep the bleb draining — this is included in the 90-day package. Vision is often blurry for a week or two. Most patients are back to light activity within days and driving at one to two weeks, once the eye is comfortable and vision meets the legal standard. Glaucoma needs lifelong monitoring, so reviews continue every few months afterwards.
Cost
At our partner clinics across southern England, private PreserFlo MicroShunt surgery is typically £4,500–£6,500 per eye, all-inclusive of the consultant glaucoma surgeon, the implant, theatre, the anaesthetist and the full 90-day aftercare package (including any needling needed in that window). A staged two-eye pathway is usually £8,500–£12,500 in total, with the second eye treated a few weeks after the first. Many patients spread the cost with 0% finance. Book a consultation from £240 for a personalised quote, or see our full price list.
Frequently asked questions
How much does private PreserFlo MicroShunt surgery cost in the UK?
At our partner clinics in southern England, private PreserFlo MicroShunt surgery is typically £4,500–£6,500 per eye, all-inclusive of the consultant glaucoma surgeon, the implant, day-case theatre, the anaesthetist and the full 90-day aftercare package (including any needling needed in that window). A staged two-eye pathway is usually £8,500–£12,500 in total. Book a consultation from £240 for a personalised quote.
How is the PreserFlo different from a trabeculectomy?
Both create a new drainage route into a bleb under the lining of the eye, but the PreserFlo does it with a precision-made tube rather than a hand-fashioned scleral flap. Its narrow channel gives a defined opening pressure of around 6 mmHg, which protects against the very low pressures (hypotony) that complicate some trabeculectomies. In the INN-005 trial, trabeculectomy reached a slightly lower average pressure, but PreserFlo needed materially fewer post-operative interventions and less needling, with a quicker return to normal life.
Will I still need glaucoma drops after PreserFlo?
Many patients come off drops entirely — around 55–65% of eyes are drop-free at two years. Most of the remainder need just a single drop (usually a prostaglandin) to reach target, and only a small minority need two drops or a further procedure. The goal is the lowest drop burden compatible with your individual target pressure, which depends on how much optic-nerve damage you have.
Is PreserFlo surgery safe? What are the main risks?
In experienced hands it has an excellent safety profile. The main early issue is a temporary low pressure (hypotony) in about 7–10% of eyes, which usually settles within a few weeks. Around 15–25% of eyes need a quick needling in the first year to keep the bleb draining (included in the aftercare package). Bleb-related infection is uncommon at roughly 0.3–0.8% per year, and serious bleeding is rare (0.1–0.4%). Careful patient selection and a disciplined follow-up schedule keep risks low.
When can I drive and get back to normal after PreserFlo?
Most patients return to light activity within a few days and to driving at one to two weeks, once the eye is comfortable and your vision meets the DVLA standard. You’ll use drops for about six to eight weeks and attend several reviews in the first three months. Avoid heavy lifting, swimming and eye-rubbing while the bleb heals; your surgeon will give you tailored advice based on your job and activities.
Does private insurance or the NHS cover PreserFlo?
Bupa, AXA Health, Aviva, Vitality and WPA generally cover PreserFlo for open-angle glaucoma with pre-authorisation, provided your policy covers chronic eye conditions and your surgeon is recognised — we prepare the pre-authorisation package for you. The MicroShunt is also offered on the NHS in specialist glaucoma units under NICE guidance IPG622, but waits are typically 12–26 weeks to listing and longer to surgery; the private pathway compresses this to one to two weeks.