Technology and Techniques for Precision, Customization, and Optimized Safety: Microinvasive Refractive Cataract Glaucoma Surgery
Narrative Responses:
Purpose
To describe advancements and treatment algorithms of micro-invasive glaucoma surgery (MIGS), and to update the body of clinical evidence that shows intraocular pressure (IOP) and medication burden for treatment of open-angle glaucoma (OAG).
Methods
The foundation of trabecular bypass technology in the MIGS algorithm is 50- 90% of resistance to aqueous is in the trabecular meshwork, a single patent trabecular bypass can increase outflow facility, and multiple bypass can further reduce IOP. Trabecular bypass stents can be used as initial therapy to restore natural physiologic outflow in OAG. With multiple stents, titratable IOP reduction (≤ 15 mmHg) is possible with minimal risk of hypotony, and long-term sustained efficacy and safety. To achieve further IOP reduction in refractory OAG, one can consider as the next step either topical ocular hypotensive medication, suprachoroidal stent, or both.
Results
A large-scale prospective, randomized study of iStent with cataract surgery (Samuelson, et al.,Craven, et al.) demonstrated that iStent offers long-term IOP control, reduced medication burden and a favorable safety profile. Five-year follow-up of this study will be presented. The long-term efficacy and safety through five years was corroborated by Fea, Neuhann, Au and Arriola-Villalobos, et al. Long-term findings through 2 years by the MIGS study group have demonstrated sustained efficacy and safety to 18 mmHg or lower with one trabecular bypass stent and to 15 mmHg or lower with multiple stents.
Conclusion
OAG patients can safely achieve IOP ≤ 18mmHg with reduced medication burden using one trabecular stent and ≤ 15mmHg with two stents as initial therapy. Continued standard-of-care evolution to episcleral venous target pressures via trabecular bypass combined with one medication or a suprachoroidal stent is possible for more advanced disease.