Minimally invasive glaucoma surgery (MIGS)
A group of small, keyhole procedures to lower eye pressure in milder glaucoma, often done at the same time as cataract surgery.
✓ Medically reviewed by a GMC-registered consultant · last reviewed September 2026 · next review September 2027 · how we review
In short
- MIGS is a group of small keyhole procedures that lower eye pressure in mild to moderate glaucoma, often combined with cataract surgery.
- It is generally lower-risk and quicker to recover from than traditional glaucoma surgery, but the pressure-lowering effect is usually more modest.
- It may reduce, but not always remove, your glaucoma drops, and the effect can fade over time, sometimes needing further treatment.
- It protects remaining vision rather than restoring lost sight; it is usually not suitable for advanced glaucoma needing a big pressure drop.
A plain-English summary. The detail — including risks and recovery — is below.
At a glance
A general guide. Your surgeon will give you advice for your situation.
Can lower eye pressure with less disturbance to the eye than traditional glaucoma surgery
Advanced glaucoma needing a large pressure drop, where MIGS alone is usually not enough.
Vision is blurry and the eye may be gritty and red. Eye pressure may be checked, as it can briefly rise. Rest, avoid rubbing the eye, and do not drive.
An early pressure check, as pressure can briefly rise after surgery.
Vision is blurry and the eye may be gritty and red. Eye pressure may be checked, as it can briefly rise. Rest...
Vision usually improves, especially if combined with cataract surgery. Use prescribed drops as directed and attend...
The eye settles and the surgeon assesses how much the pressure has fallen and whether drops can be reduced.
You continue regular glaucoma monitoring, as the effect can fade over time and your glaucoma still needs lifelong...
What is minimally invasive glaucoma surgery (MIGS)?
Glaucoma is a condition where high pressure inside the eye can gradually damage the optic nerve and reduce vision. Minimally invasive glaucoma surgery (MIGS) is a group of small 'keyhole' procedures that lower eye pressure with less disturbance to the eye than traditional glaucoma surgery.
Most MIGS procedures work from inside the eye through a tiny opening, often placing a very small device (a 'stent', for example an iStent) into the eye's natural drainage system to help fluid leave more easily. Unlike a trabeculectomy, MIGS usually does not create an external reservoir ('bleb'), which is part of why it tends to be lower-risk.
MIGS is most often done at the same time as cataract surgery, in people with mild to moderate glaucoma, to lower pressure and reduce the number of eye drops needed. It is generally not enough on its own for advanced glaucoma needing a large pressure drop.
It is important to be realistic. MIGS usually gives a more modest pressure reduction than traditional surgery, may reduce but not always stop your drops, and can lose effect over time. It protects vision rather than restoring sight already lost.
Types & techniques
There isn't one single operation. The right approach depends on you — which is something to discuss with your surgeon.
MIGS vs traditional glaucoma surgery (trabeculectomy)
| Feature | MIGS | Trabeculectomy |
|---|---|---|
| Glaucoma severity | Mild to moderate | Moderate to advanced |
| Pressure-lowering power | Usually modest | Strong |
| Creates a bleb? | Usually no | Yes |
| Recovery / follow-up | Usually quick | Several weeks, intensive |
| Often combined with | Cataract surgery | Sometimes cataract surgery |
MIGS and traditional surgery suit different stages of glaucoma. Your surgeon advises based on how advanced your glaucoma is and your target pressure, not on which is 'newest'.
Preparing for your surgery
- Discuss how advanced your glaucoma is and whether MIGS alone is likely to lower your pressure enough.
- Ask whether it will be combined with cataract surgery, and what each part is expected to achieve.
- Tell the team about all your eye drops and medicines, including blood thinners.
- Ask what is expected to happen to your glaucoma drops afterwards — reduction is the aim, not a guarantee.
- Arrange a lift home, as your vision will be blurry at first.
- Plan a few days of taking it easy, avoiding heavy lifting and rubbing the eye.
- Make sure you understand this protects your vision rather than improving sight already lost.
What happens
MIGS is usually done with anaesthetic eye drops or a local anaesthetic, sometimes with light sedation, so the eye is numb but you are awake. You lie flat and a clip gently holds the eyelids open.
The surgeon works through a tiny opening at the edge of the cornea — often the same opening used for cataract surgery — and, using a microscope and a special lens, places a small device into, or opens up, the eye's natural drainage system. There is usually no external wound to stitch and no bleb is created.
Done alone, a MIGS procedure often takes only around 10–20 minutes; combined with cataract surgery it takes longer. Most people go home the same day. Your eye pressure may be checked afterwards, and you go home with drops and instructions once the surgeon is satisfied.
Is this operation right for me?
A good consultation should explore whether it's the right choice for you now — including reasons to wait or consider something else.
May not be suitable if…
- Advanced glaucoma needing a large pressure drop, where MIGS alone is usually not enough.
- Narrow-angle, neovascular, traumatic or certain other secondary glaucomas, depending on the device.
- A drainage angle or meshwork that is scarred or abnormal in a way that prevents the device working.
- Glaucoma already well controlled, where the small added benefit may not justify surgery.
- Unrealistic expectations of a large pressure drop or being completely drop-free.
Delay surgery if…
- You have an active eye infection or significant inflammation.
- Blood-thinning medicines need adjusting and this has not yet been arranged.
- Your pressure is acutely very high and needs stabilising first.
- Other urgent eye or general-health problems need treating first.
- You are unsure and want time to weigh MIGS against other options.
Alternatives to discuss
- Continuing or changing glaucoma eye drops.
- Laser treatment of the drainage (such as SLT).
- Traditional glaucoma surgery (trabeculectomy or a drainage tube) for a bigger pressure drop.
- Cataract surgery alone, which can modestly lower pressure in some eyes.
- Close monitoring without surgery if the glaucoma is mild and stable.
Before you decide
Use this as a shared-decision checklist. The aim is not just “can this be done?”, but whether it is right for you, now, with the risks and alternatives clearly understood.
What matters most to me?
Think about symptoms, daily life, work, caring responsibilities, sport, fertility, travel, appearance and anxiety — the right choice depends on your priorities, not just the medical facts.
What are all my options?
Ask about waiting, monitoring, medicines, rehabilitation, a smaller or larger procedure, a different test, NHS referral, or a second opinion where that would help.
What would make me pause?
Active infection, pregnancy, unstable medical problems, smoking, medicines that increase bleeding, poor support at home, or feeling pressured are all reasons to slow down and get tailored advice.
What happens if I do nothing today?
For some problems, waiting is safe; for others, delay can make treatment harder. A good consultation should explain the trade-off in plain English.
Anaesthetic choices
The safest option depends on the operation, your health, the facility and your surgeon/anaesthetist. Ask what is planned and why.
Benefits
- Can lower eye pressure with less disturbance to the eye than traditional glaucoma surgery
- Often reduces the number of glaucoma drops needed
- Usually a quicker recovery and fewer follow-up visits than trabeculectomy
- Can be combined conveniently with cataract surgery in one operation
- Generally a lower risk of the serious complications seen with bleb-based surgery
Risks & complications
- Blurry vision for a few days while the eye settles
- A red, gritty or watery eye early on
- A small amount of bleeding inside the front of the eye, usually clearing within days
- A short-term rise in eye pressure soon after surgery
- The device becoming blocked or moving out of position
- Not enough pressure lowering, so you still need glaucoma drops
- Inflammation inside the eye that needs extra drops
- Loss of effect over time, sometimes needing further treatment or more invasive surgery
- Infection inside the eye (endophthalmitis), which is sight-threatening and needs urgent treatment
- More significant bleeding inside the eye
- Lasting reduction in, or loss of, vision
MIGS is generally lower-risk than traditional glaucoma surgery, but it is still surgery inside the eye and carries the rare but serious risk of infection. Its main limitation is effectiveness: the pressure drop is usually modest, may not remove all your drops, and can fade over time. Ask your surgeon how much pressure lowering is realistic for you, what happens if it is not enough, and whether your glaucoma is really mild enough for MIGS.
Published figures to discuss
MIGS covers many different devices and techniques, and the evidence base is still developing, so success and complication figures vary a lot and much of the evidence is short- to medium-term. Reviews generally describe a good safety profile but more modest and less certain pressure-lowering than traditional surgery, and outcomes depend on the device, the eye and whether cataract surgery is done at the same time.
| Figure | Reported range | How to interpret it | Source / confidence |
|---|---|---|---|
| Lowering eye pressure and drop use | Studies report meaningful reductions in many eyes (for example a fall around a third in some iStent reports), but the evidence quality is low and effects vary | A success measure; benefit is usually modest, may not remove all drops, and can fade over time. | Guide sourcesClinical context |
| Short-term rise in eye pressure after surgery | Recognised early complication; reported rates vary by device, roughly 1–33% in trial summaries | Often managed with drops; one reason pressure is checked soon after surgery. Robust single percentages vary by device, so this is qualitative. | MIGS safety and complications systematic review — PMCpmc.ncbi.nlm.nih.govPublished figure |
| Bleeding inside the front of the eye (hyphaema) | Recognised early complication; often low single figures in stent trials but higher with some angle-cutting procedures | More likely with some techniques that open the drainage meshwork. | MIGS safety and complications systematic review — PMCpmc.ncbi.nlm.nih.govSource-linked context |
| Infection inside the eye (endophthalmitis) | Rare, as with other intraocular surgery | Sight-threatening and needs urgent treatment; robust single percentages are not reliable, so this is qualitative. | MIGS safety and complications systematic review — PMCpmc.ncbi.nlm.nih.govSource-linked context |
These are literature figures, not a personalised prediction. Your own risks and likely benefits depend on your circumstances, your health, and how your care is carried out and followed up.
Recovery — what to expect, and when
Recovery from MIGS is usually quicker and gentler than traditional glaucoma surgery, especially when done with cataract surgery, though the eye still needs care and the pressure-lowering effect is judged over the following weeks.
- Blurry vision for a few days that gradually clears
- A red, gritty or watery eye early on
- Some awareness of light sensitivity for a short time
- Needing to use drops for a few weeks
- Vision fluctuating a little while the eye settles
Aftercare
- Use all prescribed drops (anti-inflammatory, antibiotic and any pressure-lowering) exactly as directed.
- Do not rub or press the eye, and wear any protective shield at night as advised.
- Avoid swimming pools, hot tubs and dusty environments for the advised period.
- Avoid heavy lifting and strenuous activity in the first days to weeks.
- Attend the early pressure check, as a temporary rise in pressure can occur.
- Ask before changing or stopping any glaucoma drops in either eye.
- Keep long-term glaucoma monitoring appointments, as the effect can lessen over time.
- Lift home arranged
- All prescribed drops collected and a dosing plan understood
- Protective eye shield ready if advised
- Early pressure-check appointment booked
- A clear plan for which glaucoma drops to continue
- Long-term glaucoma monitoring plan understood
- Clinic's urgent/out-of-hours number saved in case of pain or vision change
Scars and how they heal
MIGS is done through a tiny opening at the edge of the cornea, usually with no stitch and no external wound, so there is no skin scar. Most MIGS procedures do not create a bleb. If a device is used, it sits inside the eye where it cannot be seen.
⚠ Get urgent help if…
- Severe or increasing eye pain
- A sudden drop in or loss of vision
- Growing redness, light sensitivity or discharge (possible infection inside the eye — an emergency)
- Severe headache or eye ache with nausea, or seeing haloes (possible raised pressure)
- Vision that is getting worse rather than better over the first days
- Any of these should prompt immediate contact with your eye team or urgent eye care
Who to contact: your surgeon or clinic first (keep their number to hand). For urgent advice when you can't reach them, call NHS 111. In an emergency, call 999.
General guidance — it doesn't replace the specific advice your surgeon gives you.
Results & realistic expectations
A good result is a modest, useful fall in eye pressure that helps protect your remaining vision, often allowing fewer glaucoma drops. When combined with cataract surgery, your vision usually also improves from the cataract part of the operation. Studies suggest MIGS can reduce pressure and drop use in suitable eyes, though the evidence on how large and lasting the benefit is remains limited.
MIGS protects sight rather than restoring it: vision already lost to glaucoma does not return. The pressure-lowering effect is usually more modest than traditional surgery and may not remove all your drops.
The benefit from MIGS can lessen over time — a device may become less effective or the eye's drainage can change — so some people need additional drops, a repeat procedure or, eventually, more powerful glaucoma surgery. Because glaucoma is a lifelong condition, you will need ongoing monitoring regardless of how well the MIGS procedure works initially.
Combining with other procedures
MIGS is very often combined with cataract surgery, so one operation both improves cataract-related vision and helps lower eye pressure. It can also be a step before traditional glaucoma surgery if the glaucoma later needs a bigger pressure drop. Your surgeon will explain where MIGS fits within your overall glaucoma plan of drops, laser and, if needed, more invasive surgery.
Follow-up & long-term care
You should be seen soon after surgery to check eye pressure and healing, then over the following weeks to judge how much the pressure has fallen and whether drops can be reduced. Long-term, you continue regular glaucoma monitoring of pressure, the optic nerve and visual fields, because the effect can fade. Report pain or worsening vision immediately.
- Attend lifelong glaucoma monitoring (eye pressure, optic nerve and visual field tests).
- Use any continuing glaucoma drops exactly as prescribed, and check before changing them.
- Stay alert for infection and raised-pressure warning signs.
- Expect that further treatment may be needed over the years if the effect lessens.
- Have your other eye monitored too, as glaucoma often affects both eyes.
Revision and secondary surgery reality
- A device can become blocked or move, and the pressure-lowering effect can fade over time.
- Some people need additional drops, a repeat procedure, or eventually more powerful glaucoma surgery.
- If combined with cataract surgery, the cataract benefit is separate from the glaucoma benefit.
- Because glaucoma is lifelong, ongoing monitoring and possible further treatment should be expected.
Ask your surgeon for their own revision rate, what counts as a revision, and what is included in the written aftercare policy.
What good aftercare looks like
- An early pressure check, as pressure can briefly rise after surgery.
- Clear instructions on which glaucoma drops to continue, and a review of whether they can be reduced.
- A named contact route and written warning signs for infection and raised pressure.
- A long-term plan for monitoring pressure, the optic nerve and visual fields.
- An honest plan for further treatment if MIGS does not control the pressure or the effect fades.
What affects the cost
Costs vary a great deal between people and providers, and we don't publish prices. What matters is understanding what drives the cost and making sure your quote is complete. The main things that affect it:
- The type of MIGS procedure and any device (stent) used
- Whether it is combined with cataract surgery
- The surgeon's experience and seniority
- Whether assessment, the procedure and follow-up are included
- The clinic and facility fees
- Long-term glaucoma monitoring and the policy if further treatment is needed
- Whether the price covers the device, the procedure and any combined cataract surgery
- Whether all follow-up appointments and pressure checks are included
- Whether long-term glaucoma monitoring is included or arranged separately
- Which device or technique is included and why it suits you
- The named operating surgeon
- What happens, and what it costs, if it does not lower pressure enough or the effect fades
- What happens, and what it costs, if a complication such as infection occurs
On the NHS? Several MIGS procedures are funded by the NHS in suitable cases (NICE has assessed them), often combined with cataract surgery; private care may be chosen for timing or choice of surgeon.
You're entitled to your total cost in writing — including aftercare and any revision — before you decide.
Consent traps and marketing red flags
These are not small details. They are often where patients lose choice, time to reflect, or realistic expectations.
Consent traps
- Expecting a large pressure drop or to come off all drops when MIGS usually offers a modest benefit.
- Not being told the effect can fade and further treatment may be needed.
- Confusing the cataract benefit with the glaucoma benefit when the two are combined.
- Down-playing the rare but serious risk of infection because the procedure is 'minimally invasive'.
- No plan for what happens, and who to contact, if the pressure is not controlled.
Marketing red flags
- Promising MIGS will 'cure' glaucoma or get everyone off drops.
- Implying it carries no real risk because it is keyhole or 'micro'.
- Pushing a particular device as suitable for all glaucoma, including advanced disease.
- Suggesting it restores lost vision rather than protecting remaining sight.
- Quoting only a headline price with no long-term monitoring plan.
Choosing a surgeon safely
- Check your surgeon is on the GMC Specialist Register for this area.
- Make sure they practise at a CQC-registered location, and look for membership of bodies like BAAPS or BAPRAS.
- You're entitled to a two-stage consent process with time to reflect (a cooling-off period). The surgeon who will operate must consent you — not a salesperson.
- Be wary of pressure: time-limited offers, discounts or deposits taken before you've had time to think are red flags, not bargains.
- You're entitled to your total cost in writing — including aftercare and any revision — before you decide.
Questions to ask your medical professional
Take this to your consultation. A good surgeon will welcome every one of these.
- Is my glaucoma mild enough that MIGS is likely to lower my pressure enough?
- Will this be combined with cataract surgery, and what is each part expected to achieve?
- How much pressure lowering and drop reduction is realistic for me?
- What happens if it does not lower my pressure enough, or the effect fades?
- Which device or technique are you using, and why is it right for my eye?
- How will I be monitored long-term, and who do I contact urgently for pain or vision change?
- Are you on the GMC Specialist Register for this area, and which Royal College or professional body are you a member of?
- Will you be the surgeon who carries out my operation, and who looks after me afterwards?
- What are the risks for someone like me, and how often do your own patients have a problem or need it repeated or redone?
- What does a realistic result look like — and what can this operation not achieve?
- What are my options, including waiting, doing nothing for now, or choosing a different approach?
- Can I have written information, results and aftercare instructions in a format I can use, including any accessibility or communication support I need?
- What is the total cost in writing, including any follow-ups, and how much time do I have to decide?
Frequently asked questions
Is MIGS available on the NHS?
How is MIGS different from a trabeculectomy?
Will MIGS get me off my eye drops?
Will it improve my vision?
Is MIGS suitable for advanced glaucoma?
How long is the recovery?
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How we made this page
Medically reviewed by a GMC-registered consultant. Written in plain English, checked against NHS, NICE, GMC and relevant Royal College / specialist-society guidance, and kept under review. No clinic paid to appear on this page, and we publish no pricing. This is general information to help you prepare — it is not a substitute for advice from your own clinician. How we review our guides →
Source hierarchy: UK regulator and NHS/NICE guidance first, then relevant Royal College or specialist-society guidance, then peer-reviewed evidence for procedure-specific figures where available.
Sources & standards: NHS — Glaucoma NICE — Glaucoma: diagnosis and management (NG81) NHS (Dudley Group) — MIGS / iStent inject patient information Microinvasive glaucoma surgery — review (PMC) MIGS safety and complications systematic review — PMC American Academy of Ophthalmology — reporting endpoints in MIGS studies
Reviews reflect patients' experience of care, not clinical outcomes. For procedure volumes and outcome data see PHIN.
Last medically reviewed 2026-09-21. Spotted something wrong or out of date? Report an error in this guide.
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