[Subconjunctival minimally invasive glaucoma surgery : Methods and clinical results]

Minimally invasive glaucoma surgery (MIGS) has been developed for all drainage pathways in glaucoma treatment. Besides implants overriding the resistance in the trabecular meshwork (iStent®, iStent Inject® [both Glaukos Germany GmbH, Wiesbaden, Germany], Hydrus Microstent® [Ivantis, Irvine, CA, USA]) and draining to the suprachoroidal space (Cypass Micro Stent® [Alcon Laboratories, Inc., Fort Worth, TX, USA], iStent Supra® [Glaukos Germany GmbH]), surgeons can further drain aqueous humor into the subconjunctival space with a transscleral MIGS implant (XEN45® [Allergan Plc., Dublin, Irland]). The XEN45® is a gelatine tube 6 mm in length, which is implanted ab interno via a small corneal incision through the sclera. Additional aqueous humor is drained from the anterior chamber via the tube and filtered in a filter cushion in order to sink the total drainage resistance. The internal diameter of the lumen of the implant is 45 µm, therefore a passive resistance is present for prevention of postoperative hypotension. The by-passed aqueous humor forms a conjunctival bleb. Although the first study results are promising in terms of efficacy and safety, further studies are necessary before a clear picture of the effectiveness, safety, advantages and disadvantages of the gelatine tube can be drawn.