Minimally Invasive Glaucoma Surgery (MIGS)

Why MIGS exists

Traditional glaucoma surgery (trabeculectomy and drainage tubes) lowers pressure powerfully but carries meaningful risks and a long recovery, so it is reserved for advanced disease. Between drops and that surgery there was a gap: patients with mild or moderate glaucoma who were poorly controlled on drops, or who could not tolerate them, had few options. MIGS fills the gap with procedures that are safer than filtration surgery, more effective than laser for some patients, and conveniently combined with the cataract surgery many of these patients need anyway.

The types

• Trabecular micro-bypass stents: one or more tiny titanium or nitinol stents placed through the meshwork into the natural drainage canal, creating a direct path for fluid; performed through the cataract incision
• Canal-based procedures: a micro-catheter or device dilates or removes a section of the trabecular meshwork to open the natural drain
• Subconjunctival micro-stents: a small tube that drains fluid to a space under the conjunctiva, for patients needing lower pressures; somewhat more involved

Laser cyclophotocoagulation, which treats the fluid-producing tissue, is a separate glaucoma procedure rather than MIGS and is used in selected cases.

Combined with cataract surgery

Cataract surgery itself lowers pressure modestly. Adding a MIGS procedure, through the same incision, typically lowers it further and reduces the number of drops afterward, often to none in mild disease. The added operating time is a few minutes and recovery is essentially that of cataract surgery. For a patient with both a cataract and glaucoma this is often the best opportunity to improve control with the least additional risk, and it is discussed at the cataract evaluation of a glaucoma patient, with referral to a glaucoma subspecialist where appropriate.

Expectations and limits

MIGS lowers pressure moderately, not dramatically. It suits mild to moderate open-angle glaucoma with a target in the mid to high teens. Advanced disease needing very low pressures still requires filtration surgery, which is arranged with a glaucoma subspecialist. Devices and eligibility vary, and your surgeon will tell you which, if any, is appropriate for your eye.