Inclusion Criteria:
1. Age, Capacity \& Consent:
1. Be 18 years of age or older.
2. Be able to understand all study instructions, and willing to comply with all study procedures and the visit schedule.
3. Provide written, informed consent to participate.
2. Glaucoma in the study eye, meeting all of the following requirements:
1. Diagnosed by the investigator, based upon untreated intraocular pressure, disc appearance and visual field abnormalities.
2. The glaucoma type is one of:
i. Primary open angle glaucoma (POAG). ii. Chronic angle closure glaucoma (CACG) where the eye is pseudophakic. iii. Mixed mechanism POAG/CACG where a laser iridotomy has previously been performed.
iv. Pigmentary open angle glaucoma. v. Exfoliation open angle glaucoma. vi. Neovascular glaucoma that is treated and regressed/quiescent. c. Glaucoma drainage surgery is indicated due to failure of previous treatment (the glaucoma is 'refractory'), with failure of maximum tolerated medical therapy and one of the following circumstances: i. No previous glaucoma surgery. ii. Prior trabecular bypass (using iStents or Hydrus) or cilioablation. iii. Failure of one prior glaucoma drainage operation (that is one of trabeculectomy, deep sclerectomy or Xen).
d. The mean diurnal IOP at Baseline is greater than or equal to 20 mmHg and less than or equal to 40 mmHg.
e. The conjunctiva in the target quadrant is suitable for glaucoma surgery.
Key Exclusion Criteria:
* Advanced glaucomatous optic neuropathy that threatens fixation, in the opinion of the investigator.
* The glaucoma type is any of the following:
1. Acute Angle Closure Glaucoma (AACG).
2. Chronic Angle Closure Glaucoma (CACG) where the eye is phakic.
3. Congenital glaucoma. Juvenile Open-Angle Glaucoma or Congenital Glaucoma.
4. Secondary glaucoma of any type not specified in the inclusion criteria, including inflammatory glaucoma, active neovascular glaucoma, traumatic glaucoma, Iridocorneal Endothelial (ICE) Syndrome, and silicone oil induced glaucoma.
* Previous glaucoma surgery with:
1. A tube-and-plate glaucoma drainage implant (GDI, e.g. Molteno, Baerveldt, Paul).
2. A suprachoroidal implant.
3. Multiple previous operations for glaucoma.
4. Glaucoma surgery within 3 months of screening.
* Cataract surgery or any other ocular surgery is indicated at the time of study intervention or is anticipated to be required during the study duration.
* Conjunctival scarring or pterygium in the target quadrant.
* Severe dry eye disease.
* Significant corneal disease.
* Accurate measurement of baseline central corneal endothelial density is not possible.
* Any treatment or condition that, in the opinion of the investigator, may impact corneal endothelial cell density beyond expected age \& disease-related decline.
* Significant retinal or posterior segment pathology, including but not limited to:
1. Active and clinically significant diabetic retinopathy.
2. Active choroidal neovascularization, branch retinal vein occlusion, central retinal vein occlusion, proliferative retinopathy.
3. Intraocular silicone oil.
4. Presence of a scleral buckle.
* Vitreous present in the anterior chamber.
* Active uveitis or clinically significant infection or inflammation.
* Unfit for surgery under local anaesthetic.
* Any uncontrolled systemic disease.
* The participant is pregnant, breastfeeding, or cannot guarantee they will not conceive or donate sperm or eggs during the study.
* Significant risk of bleeding.
* Any other clinical or social reason that, in the opinion of the investigator, means standard surgical treatment for glaucoma would be considered safer than participation in the study.
