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ESP 
Glaucoma is one of the leading causes of blindness worldwide, and its management has evolved significantly. Today, minimally invasive glaucoma surgeries (MIGS and MEPS) offer safer and more effective alternatives for controlling intraocular pressure (IOP). This article explores the latest trends and technologies in the field, based on an analysis of the document "SAMUR A-I #7: MIGS / MIBS SHOWDOWN", with a focus on IOP reduction, safety profile, and patient selection.
A Paradigm Shift in Glaucoma Treatment
Traditionally, trabeculectomy has been the gold standard for the surgical treatment of glaucoma. However, the current landscape has seen a "radical shift" toward less aggressive options. MIGS and MEPS aim to lower IOP to moderate ranges (between 10 and 16 mmHg) with a superior safety profile, offering a "much broader and, overall, safer therapeutic arsenal than trabeculectomy". The goal is to find the perfect balance between IOP reduction and safety, always selecting the ideal patient for each technique.
Flow Pathways and Specific Technologies in Glaucoma Surgery
Minimally invasive glaucoma surgeries are classified according to the flow pathway they seek to optimize:
1. Improvement of Trabecular Flow (Natural Route)
These techniques facilitate the outflow of aqueous humor through its natural pathway: Schlemm's canal and the trabecular meshwork.
- Implants/Scaffolds:
- iStent family: Implants designed to improve drainage. The newest versions allow multiple iStents to be placed for a greater effect.
- Hydrus: A small scaffold inserted into Schlemm's canal to keep it open. There are comparative data with iStent that spark debate about its superiority.
- Tissue Ablation/Cutting:
- Trabectome: Uses electrocautery to ablate trabecular tissue.
- Blade Goniotomies (Kahook Dual Blade, KDB): Allow precise cutting of the tissue.
- Bang Bent of Internal Needle Goniotomy (BANG): An "ingenious and accessible" technique that uses a bent insulin needle to perform the goniotomy. It stands out for its cost-effectiveness. Combined with phacoemulsification (cataract surgery), it has shown a 27% reduction in IOP and a 55% reduction in medication use at 6 months.
- Extensive Trabeculotomies:
- Transillumination-Assisted Goniotomy (GAT): A 360-degree trabeculotomy that opens the entire canal. It achieves "quite remarkable" IOP reductions of approximately 9.3 mmHg. However, it has the highest rate of transient hyphema (bleeding inside the eye), almost 28%, because more tissue is cut.
- OMNI: Combines canaloplasty and trabeculotomy.
- Internal AV Microhook: Has shown "36-month data", suggesting durability.
- HFDS: With "impressive 6-year results", which "gives confidence in its durability".
It is important to note that there is a clear "efficacy-safety balance": greater intervention in the trabecular meshwork, as with GAT or Microhook, often leads to a greater IOP reduction, but also a slightly higher risk of hyphema. In addition, if baseline IOP is high, the reduction tends to be greater in absolute numbers.
2. Suprachoroidal Flow
This route creates an alternative pathway between the choroid and the sclera.
- MiniJet: The device currently available for this route, with "5-year data" and a 38% reduction in IOP, as well as a "good safety profile".
- Safety Considerations (The CyPass Lesson): The withdrawal of the CyPass device due to long-term endothelial cell loss was a "hard lesson" about the importance of long-term follow-up. It underscored that design, material, and monitoring of patients over years are vital. The success of MiniJet suggests that the suprachoroidal route is viable with the right design.
3. Subconjunctival discharge (MIBS)
These techniques are closer to trabeculectomy, since they create a filtering bleb so that aqueous humor drains into the subconjunctival space.
- Ex-Press Gel Stent, XEN63, and PreserFlo MicroShunt: Achieve "more powerful" IOP reductions, sometimes 40-55%, approaching the results of trabeculectomy. (Watch the PresserFlo episode by clicking here)
- Bleb Management: Unlike trabecular MIGS, success here depends on healing of the outer conjunctiva. Mitomycin C is frequently used to prevent excessive scarring and, at times, needling is needed to keep the bleb functional.
- Complication Profile: They introduce a different complication profile, with less risk of hyphema but a higher risk of bleb-related problems such as leaks, hypotony, or, rarely, infection.
4. Reduction of aqueous humor production
These techniques act on the ciliary body, the "factory" of aqueous humor.
- Endoscopic Cyclophotocoagulation (ECP): Allows the ciliary body to be visualized and treated from the inside.
- Micropuls TSPC: Delivers the treatment externally, with a technology that aims to be "gentler and safer" and less destructive than traditional cyclophotocoagulation. These techniques are particularly useful in very advanced or refractory glaucomas.
Key Findings and Future Implications in Glaucoma
The field of minimally invasive glaucoma surgery has advanced considerably, offering new hope to patients:
- A Broad and Safe Therapeutic Arsenal: Ophthalmologists have a "much broader therapeutic arsenal" that is, overall, safer than trabeculectomy for controlling IOP in moderate ranges (10-16 mmHg).
- Efficacy-Safety Balance: It is essential to understand that the most powerful techniques, such as GAT or MIBS, achieve greater IOP reductions but carry different risks (hyphema or bleb complications).
- Patient Selection Is Crucial: "Patient selection is crucial". Factors such as baseline IOP, the state of the iridocorneal angle, glaucoma severity, age, and the presence of cataract are decisive. Nomograms are being developed to help with this decision-making.
- Long-Term Data and Durability: The experience with CyPass highlights the need for "long-term data, always". Durability and cost are essential factors in daily practice.
- Continuous Innovation: Innovation does not stop, with examples such as BANK for its cost-effectiveness, MiniJet validating the suprachoroidal route, and Micropuls improving safety.
Finally, a "final reflection" is raised: the role of Artificial Intelligence (AI). AI could analyze various patient factors (OCT, medical history, genetics) to "refine our ability to predict who will respond best to which technique". This would take the personalization of glaucoma surgery to a new level, with the ability to "predict individual response being the next big step".
