Minimally Invasive Glaucoma Surgery (MIGS) | PristynCare

Risk Factors

Patients most suitable for advanced MIGS include those with:

• Moderate to advanced open-angle glaucoma not controlled on 2 or more drops
• Patients who are intolerant of multiple eye drop medications
• Those wishing to reduce medication burden alongside cataract surgery
• Glaucoma patients with mild conjunctival scarring not suitable for trabeculectomy
• Patients with elevated IOP after previous trabeculectomy revision

Who is a Candidate

Advanced MIGS candidates include patients with open-angle glaucoma with moderate to advanced damage who require more IOP lowering than standard trabecular MIGS can provide, but who wish to avoid trabeculectomy. Patients with mild to moderate conjunctival disease, prior cataract surgery, or desire for faster recovery are particularly suitable for Xen or PreserFlo procedures.

Diagnosis

Pre-operative assessment for advanced MIGS includes:

• Gonioscopy to confirm open angle and assess trabecular meshwork
• IOP measurement on maximum tolerated medication
• Visual field testing to document severity of damage
• OCT RNFL and optic disc imaging for baseline documentation
• Corneal endothelial cell count before any anterior chamber device
• Conjunctival health assessment for bleb-forming procedures

Treatment Plan

The choice of advanced MIGS procedure depends on target IOP, conjunctival health, prior surgeries, and glaucoma type. For mild to moderate open-angle glaucoma combined with cataracts, phaco-iStent or phaco-Hydrus is preferred. For more significant IOP reduction, Xen gel stent or PreserFlo with or without cataract extraction is chosen. Target IOP and medication burden guide post-operative management.

Advanced MIGS Procedure Steps

The Xen gel stent implantation procedure (representative advanced MIGS) involves:

• Pre-operative mitomycin C (MMC) injection into the subconjunctival space to prevent fibrosis
• A corneal side-port incision and a main paracentesis are made
• The Xen applicator is introduced into the anterior chamber through the corneal incision
• The stent is deployed through the trabecular meshwork, sclera, and into the subconjunctival space
• Correct positioning is confirmed – the stent should extend 2 mm subconjunctivally
• The anterior chamber is reformed with balanced salt solution
• A low diffuse bleb indicates proper drainage
• Post-operative topical antibiotics and steroids are started immediately

Recovery After MIGS

Recovery after advanced MIGS procedures requires:

• Post-operative bleb assessment at 1 day, 1 week, and 1 month
• Topical steroids are used more intensively than after standard cataract surgery
• Avoid eye rubbing and contact sports for 4 to 6 weeks
• Glaucoma drops may be temporarily stopped and reintroduced based on IOP response
• Needling procedure may be required if the bleb encapsulates (for Xen or PreserFlo)
• Monthly IOP monitoring for the first 6 months is recommended

Risks and Complications of Advanced MIGS

Potential complications of advanced MIGS procedures include:

• Bleb failure or encapsulation: Fibrosis around the stent reducing drainage; may require needling
• Hypotony: Excessively low IOP causing choroidal detachment or maculopathy
• Stent malposition: Incorrect placement requiring repositioning or removal
• Infection or blebitis: Bleb-related infection requiring urgent treatment
• Hyphema: Blood in the anterior chamber from trabecular injury
• IOP spike: Transient rise in IOP in the early post-operative period
• Subconjunctival hemorrhage: Common and self-limiting