Micro-invasive Glaucoma Surgery (MIGS) is the Least Invasive Surgical Option for Glaucoma
Micro-invasive glaucoma surgery (MIGS) procedures are the least invasive surgical options for glaucoma, offering a more favorable safety profile with minimal trauma to ocular tissues compared to traditional surgeries. 1
Understanding MIGS Procedures
MIGS procedures share several key characteristics that make them minimally invasive:
- Ab interno approach (from inside the eye)
- Minimal trauma to ocular tissues
- Bleb-independent (most types)
- Conjunctival-sparing
- Shorter surgical time
- Faster recovery
Types of MIGS by Target Outflow Pathway
Trabecular Outflow MIGS
- iStent and iStent inject (trabecular microbypass stents)
- Hydrus microstent
- Trabectome (ab interno trabeculectomy)
- Gonioscopy-assisted transluminal trabeculotomy
Suprachoroidal Outflow MIGS
- CyPass microstent
- iStent Supra
Subconjunctival MIGS
- XEN gel stent
Efficacy vs. Safety Considerations
While MIGS procedures provide modest IOP reduction compared to traditional surgeries, they offer significant safety advantages:
- Postoperative pressures typically in mid to upper teens 1
- Less effective in lowering IOP than trabeculectomy or aqueous shunt surgery
- Significantly fewer complications than traditional surgeries
- Often combined with cataract surgery for enhanced effect
Specific MIGS Options and Their Features
Trabecular Microbypass Stent (iStent)
- FDA-approved for use with cataract surgery in mild to moderate open-angle glaucoma
- Heparin-coated titanium device implanted into Schlemm's canal
- Studies show small but meaningful IOP reduction when combined with cataract surgery
- Multiple stents may provide better IOP lowering than a single stent
- Low complication rates (mainly stent malposition or obstruction) 1
Ab Interno Trabeculectomy (Trabectome)
- Removes strip of trabecular meshwork using high-frequency electrocautery
- Reduces IOP and medication requirements with minimal complications
- Can be combined with phacoemulsification
- Prior laser trabeculoplasty doesn't significantly affect results 1
Comparison to Other Surgical Approaches
Non-penetrating Glaucoma Surgery
- Deep sclerectomy and viscocanalostomy are less invasive than trabeculectomy
- Higher surgical difficulty than trabeculectomy
- Require special instrumentation
- Fewer complications than trabeculectomy but less effective IOP reduction 1
Canaloplasty
- Involves circumferential viscodilation of Schlemm's canal
- Combined with deep sclerectomy
- Less effective than trabeculectomy for IOP reduction
- Better safety profile than trabeculectomy 1
Traditional Surgeries (Most Invasive)
- Trabeculectomy
- Aqueous shunt implantation
- Higher complication rates including hypotony, bleb-related issues, and infection
- More effective IOP reduction but higher risk profile
Clinical Decision Making
When selecting the least invasive option:
Consider disease severity:
- MIGS is most appropriate for mild to moderate glaucoma
- More severe disease may require more invasive approaches despite higher risks
Evaluate need for combined procedures:
- MIGS is commonly combined with cataract surgery
- Combined procedures may enhance IOP-lowering effect
Assess target IOP:
- If modest IOP reduction is acceptable, MIGS offers better safety
- If very low target IOP is needed, more invasive surgery may be necessary
Limitations and Considerations
- Limited long-term data available for many MIGS procedures 1
- Uncertainty regarding comparative effectiveness of different MIGS devices 1
- Some MIGS devices have been withdrawn from market due to safety concerns
- Surgical expertise and learning curve must be considered
- Cost and insurance coverage may influence availability
MIGS represents an important bridge between medical/laser therapy and traditional invasive glaucoma surgeries, offering patients with mild to moderate glaucoma a safer surgical option with fewer complications and faster recovery.