Micro invasive glaucoma surgery (MIGS)

Micro invasive glaucoma surgery (MIGS) represents a major advancement in the management of open-angle glaucoma, offering a safer and less invasive alternative to traditional filtering surgeries. Miss Vesela Valchova, consultant ophthalmic surgeon in Cambridge, specialises in these modern micro-surgical techniques to effectively lower intraocular pressure (the fluid pressure inside the eye) while preserving the natural structure of the ocular tissues.

Glaucoma is typically caused by a build-up of fluid pressure that damages the optic nerve at the back of the eye. This article outlines the mechanical principles of MIGS, its clinical benefits, and what patients can expect during the treatment journey.

What is micro invasive glaucoma surgery?

Micro invasive glaucoma surgery encompasses a group of surgical procedures that utilise microscopic instruments and tiny medical devices to enhance the eye's natural fluid drainage pathways. It’s an increasingly common intervention, particularly for patients with mild-to-moderate glaucoma who are already undergoing cataract surgery.

Unlike traditional operations such as trabeculectomy, which require creating an artificial drainage hole in the eye wall, MIGS procedures work from within the eye through microscopic incisions. These microscopic devices, or stents, are precisely placed to bypass blockages in the trabecular meshwork; the eye's primary drainage sieve, allowing the fluid (aqueous humour) to flow away more freely.

Clinical data demonstrates that by restoring the natural fluid drainage, MIGS achieves a highly predictable reduction in intraocular pressure with an exceptionally low complication rate.

When is MIGS recommended for patients?

MIGS is primarily recommended for individuals with mild-to-moderate open-angle glaucoma whose eye pressure isn’t fully controlled by medicated eye drops, or who experience severe side effects and irritation from their daily drops. It’s frequently performed as a combined procedure alongside routine cataract surgery, as both can be completed through the same tiny, self-healing incision.

A specialist evaluation is essential to determine whether a patient's specific eye anatomy is suitable for a micro-drainage device. If a patient finds it difficult to comply with a complex eye drop regime, or if their glaucoma shows signs of steady progression despite medical therapy, a surgical assessment is highly advisable.

What are the primary types of MIGS procedures?

The selection of a MIGS technique depends on the patient's individual eye pressure targets and the specific location of the resistance within their fluid drainage system. Ophthalmic surgeons categorise these micro-interventions based on how they alter the fluid dynamics of the eye.

• Trabecular micro-bypass stents: The insertion of microscopic titanium tubes directly into the main drainage channel to create a permanent shortcut for fluid flow.
• Canaloplasty: The use of a micro-catheter to gently expand and flush out the natural circular drainage canal of the eye, restoring its original capacity.
• Subconjunctival micro-shunts: The placement of an ultra-thin, flexible tube that diverts fluid to a small space underneath the outer clear lining of the eye.
• Endoscopic cyclophotocoagulation (ECP): The targeted use of laser energy via a micro-endoscope to gently reduce fluid production from the internal tissues of the eye.

What does the recovery and long-term outlook look like?

Recovery from micro invasive glaucoma surgery is typically rapid and straightforward, with most patients experiencing minimal discomfort and returning to their normal daily activities within a few days. Because the incisions are microscopic and don’t require traditional stitches, the shape of the eye remains stable, and visual recovery is generally governed by the standard healing timeline of the accompanying cataract surgery.

Studies indicate that over 80 per cent of patients achieve a significant, sustained reduction in their intraocular pressure following a MIGS procedure, allowing many to substantially reduce or completely stop their daily glaucoma eye drops. By working alongside a specialist consultant to implement a tailored surgical plan, patients can reliably safeguard their optic nerve and preserve their long-term vision.

References

• The Royal College of Ophthalmologists. (2025). Clinical Guidelines for the Management of Open-Angle Glaucoma.
• NHS East of England. (2024). Specialised Ophthalmic Pathways: Micro Invasive Glaucoma Surgery.
• National Institute for Health and Care Excellence (NICE). (2023). Microinvasive glaucoma surgery for open-angle glaucoma (IPG752).
• British Journal of Ophthalmology. (2022). Five-year safety and efficacy outcomes of trabecular micro-bypass stents in modern glaucoma management