The surgical procedure was tested extensively ex vivo, leading to a complete implantation within 20 minutes. Briefly, microstents were inserted through a temporoinferior paracentesis using an in-house developed applicator which was described in detail elsewhere.23 The applicator device is based on a 22G × 1½” cannulated needle (Sterican, B. Braun Melsungen AG, Melsungen, Germany) attached to a handgrip including the release mechanism for the microstent, loaded inside the tip of the cannulated needle.22 ,23 The design of the injector device allows the use of a fresh sterile cannulated needle after each implantation.
The surgical implantation process is schematically demonstrated in Figure 2. The cannulated needle of the applicator penetrated the iridocorneal angle and the sclera (Fig. 2c). For microstent release under the conjunctiva, the applicator device enables the microstent to be held in position and the cannula to be withdrawn in the process, leaving the inflow ending in the anterior chamber (Fig. 2e), ensuring drainage into the subconjunctival space. Microsurgical access via the conjunctiva was created and the microstents were mattress suture fixated onto the sclera (Fig. 2f) using 10-0 nylon (MPZ671, Ethicon, Johnson & Johnson Medical GmbH, Norderstedt, Germany) to prevent dislocation.
For in vivo implantations, animals were sedated using a subcutaneous injection of 50 mg kg−1 ketamine 10% (Belapharm GmbH & Co. KG, Vechta, Germany) and 5 mg kg−1 xylazine 2% (Rompun, Bayer Vital GmbH, Leverkusen, Germany). Animals were implanted with one microstent into the right (treated) eye. The left (untreated) eye remained without an implant and served as a control. All implantations were performed by the same surgeon. After stent implantation, antibiotic eye drops (Dexa-Gentamicin, Ursapharm GmbH, Saarbrücken, Germany) were administered postsurgically to the treated eye three times a day for 5 days.