MIMS Procedure: Concept and Evaluation of Safety, Feasibility, and Efficacy in a Porcine Experimental Model

Abstract

We present a novel stentless filtration system used to create a permanent sclerocorneal drainage channel that reduces intraocular pressure (IOP) without the need to create a conjunctival incision or a scleral flap. The purpose of this study was to evaluate the safety, feasibility, and preliminary performance of a novel surgical system, the minimally invasive micro sclerostomy (MIMS), in an in vivo porcine experimental model. MIMS is an ab externo stentless filtration procedure. An activation system is used to operate a handpiece that includes a 600 µm needle containing an injectable 300 µm triangular blade that spins around its longitudinal axis. The needle is inserted into the subconjunctival space and the blade is injected at the limbal area creating a drainage channel at the sclerocorneal junction, connecting the anterior chamber to the subconjunctival space. The first generation of the MIMS surgical system was assessed in a porcine experimental model, firstly on 6 pigs and thereafter on 10 pigs. All adverse events, IOP measurements, and bleb descriptions were recorded for up to 14 weeks. The shape and location of the scleral tunnel, the subconjunctival bleb, and the healing process were examined by slit-lamp examination, by histopathologic analysis, and by anterior segment optical coherence tomography imaging. No device malfunctions were recorded. Scleral tunnels were repeatedly achieved in all models. No significant intraoperative or postoperative complications were recorded. Effective fluid percolation was achieved in all eyes. The mean IOP statistically significantly decreased from 19.0±3.2 mm Hg preoperatively to 11.1±4.9 mm Hg on the first follow-up visit (P=0.0046) in the first leg of the study, and from 18.5±3.8 to 13.3±1.9 mm Hg in the second leg (P=0.0165). In both, IOP gradually returned to preoperative values toward the end of the follow-up period, as expected in a porcine experimental model. Histologic analysis of the analyzed tissue was not associated with significant tissue reaction. The MIMS procedure exhibited a consistent and relatively high safety, feasibility, and efficacy profiles. In the future, the MIMS procedure may provide a novel solution for uncontrolled IOP.