It is an interventional study for the treatment of Primary Open-Angle Glaucoma (POAG) using the Hexiris Microinvasive Scleral Trephine (MIST) system. This medical device includes a sclerectomy punch and injector assembly. It is a multicenter, open-label, non-randomized, single-arm study. Adults aged 40 years or more will be enrolled if the POAG is inadequately controlled by topical drug therapies. Only one eye per subject will be treated. The study will be performed on the first five patients in the operating room and the subsequent 20 patients will be treated under a slit-lamp in an aseptic environment (external patient clinic).Once treated with the MIST device, patients will return the next day, 1 week later and 1, 2, 3, 6, 9 and 12 months later. During these follow-up visits, the ophthalmologist will examine the eye and take measurements of the intraocular pressure.