Minimally invasive glaucoma surgery (MIGS)

What is MIGS?

Minimally invasive (also known as micro-invasive or micro-bypass) glaucoma surgery refers to a class of surgical treatment used to manage mild-to-moderate cases of primary open-angle glaucoma. This is the most common type of glaucoma and results when the trabecular meshwork that drains aqueous fluid from the front of the eye is not working properly.

As a result, pressure in the eye (called intraocular pressure or IOP) increases and pushes on the optic nerve. Over time, damage to the nerve fibres causes peripheral (side) vision loss and eventually central vision loss.

MIGS procedures involve placing tiny medical devices in the eye to improve fluid outflow through the trabecular meshwork. This helps to reduce pressure on the optic nerve and prevent further damage.

Occasionally, MIGS may be used to treat some secondary glaucomas, such as pseudoexfoliation glaucoma or pigmentary glaucoma.

MIGS in Australia

The following implants are currently approved for use in Australia:

• iStent inject^® consists of two tiny (less than 0.4 mm) titanium stents that are implanted using a preloaded injector.¹ These stents bypass the blockage in the trabecular meshwork, allowing the aqueous humour to drain from the eye at the same rate it is produced.
• Hydrus^® is a curved, flexible stent that is roughly the size of an eyelash. Once inserted, it bypasses the trabecular meshwork and acts as a scaffold to widen the natural drainage canal.² More fluid can flow via the canal into collector channels, thereby reducing the pressure in the front of the eye.
• XEN^® gel stent is a small, 6 mm shunt made from non-degradable gelatin that softens and conforms to the shape of the eye once inserted in the front chamber of the eye.³ It diverts fluid through the trabecular meshwork into a small blister (bleb) underneath the conjunctiva (skin of the eye), just below the upper eyelid.

Medicare rebate for MIGS as a standalone procedure

MIGS is typically offered after conventional treatments (medicated eye drops, laser therapy) have failed to achieve a satisfactory reduction in eye pressure. This type of surgery has a good safety profile and can delay the need for more invasive surgical procedures (trabeculectomy, drainage devices) in some people.

Previously, patients could only qualify for a Medicare rebate for MIGS when it was combined with cataract surgery. However, as of 1 May 2020, a standalone MIGS rebate (not performed in conjunction with another surgery) is available for patients with glaucoma who fail or are not eligible for conventional treatment with drops or laser therapy.⁴

Eligible patients can receive the Medicare rebate for MIGS when it is performed by an ophthalmologist with recognised training in these procedures.

FAQs

How long does a MIGS procedure take?

MIGS in combination with cataract surgery typically takes 30–40 minutes operating time, while standalone MIGS may only take 5–10 minutes. Allowing for admission, preparation, surgery and recovery time, you should expect to be in the day surgery for around 2–3 hours.

Will the procedure hurt?

MIGS is performed under a local anaesthetic. You may feel some slight pressure on your eye during the operation, but there won’t be any pain.

Will I be able to feel the stent in my eye?

No, stents cannot be felt once placed in the eye.

How long is the recovery period for MIGS?

Recovery is rapid and typically no longer than the recovery period for cataract surgery (approximately 2–4 weeks). You will be prescribed medicated eye drops after the surgery to treat any swelling and inflammation. Your doctor will advise you on how often and how long to use the drops. You should be able to resume normal activities after 2 weeks.

Are MIGS safe?

The MIGS devices that are currently approved for use in Australia are safe. However, as with all surgical procedures, there are potential risks.

Minor postoperative complications include:

• Increase in eye pressure
• Very low eye pressure (hypotony) – this is more of a risk with XEN compared to iStent and Hydrus
• A bleed inside the eye (hyphema) is common with the iStent and Hydrus – this typically resolves a few days after surgery
• Endothelial cell loss (uncommon)

A rare but serious complication that can occur after MIGS is endophthalmitis (infection within the eye). If left untreated, this can lead to irreversible vision loss.

Will I still need my glaucoma eye drops after MIGS?

After a MIGS procedure, you will temporarily stop all your regular glaucoma medication so that your eye pressure can be reassessed and monitored. Many patients find that they no longer need glaucoma medication or can reduce the number of drops they take, but this is not guaranteed. Some patients may also need to restart eye drops or laser treatment in the future if their eye pressure goes back up.

Conclusion

When deciding the best course of treatment, your ophthalmologist will take into account your lifestyle, pre-existing eye conditions, type and severity of glaucoma and initial eye pressure. Glaucoma requires long-term management by an ophthalmologist to keep your eye pressure controlled and prevent or minimise vision loss.

Glaucoma treatment is offered at our clinics in NSW, VIC and SA.

Learn more about our glaucoma service