The purpose of this study is to compare the IOP-related fluctuations using the CLS (contact lens sensor) Sensimed Triggerfish in glaucoma patients before and after glaucoma surgery with iStent inject W under physiological conditions and compare these results with a control group of glaucoma patients treated only with hypotensive medical treatment requiring cataract surgery.

This is a prospective controlled pre-post intervention study conducted at a Hospital Clínic of Barcelona, a university hospital in Barcelona, Spain. This study will be adhered to the tenets of the Declaration of Helsinki. Informed patient consent and approval by the Institutional Review Board will be obtained prior to study commencement. Study duration is expected to be around 12 months, recruitment period would last between 6 to 8 months and study is expected to be finalized by Jun 2025.

The study will recruit consenting adults (over 18 years old) with unilateral or bilateral primary open-angle glaucoma (POAG) without previous eye surgery, treated with topical anti-glaucoma medications, who need glaucoma surgery with iStent inject W. The investigators will include patients with isolate iStent surgery and patients with combined cataract and iStent surgery. In cases of bilateral glaucoma, the two eyes of the same patient may be included consecutively.

One month prior to glaucoma surgery with iStent inject W, subjects will wear the CLS for 24 hours without changing the regimen of anti-glaucoma eye drops. The CLS will be placed on the subject's eye by an ophthalmologist in the clinic after a slit lamp examination and keratometry to determine the corneal curvature for selection of the appropriate CLS base curve. The subjects will then return home and carry on their routine activities (both indoor and outdoor), apart from showering or swimming (as the device cannot be in contact with water). Subjects will continue the same regimen of anti-glaucoma eye drops and slept in their habitual position at night. Each subject will carry a logbook to record sleeping and medication instillation times during the 24-hour period. After 24 hours, the subject will return to the clinic to have the contact lens removed followed by a slit lamp examination. The data recorded by the CLS will be uploaded into a computer database. Goldmann applanation tonometry (GAT) will be perform before and after each CLS wear by a single observer. At 1-month (n=9/44) and 3-month (n=44) post-glaucoma surgery with iStent implant, patients will wear the CLS in the same eye that received the first CLS recording. As before, the CLS will be removed 24 hours later. To extend the follow-up to 3 months after surgery will allow us to corroborate that the effects of the surgery on fluctuations of IOP for 24 hours are maintained over time. In the control group (n=10) , a first monitoring with CLS will be carried out one month before cataract surgery, and a second monitoring will be carried out 3 months after this cataract surgery, without us having introduced any changes in their hypotensive medical treatment.

Inclusion Criteria:

• Adult Patients (over 18 years old) with an initial diagnosis of POAG requiring an indication from the patient chart of an untreated IOP of over 21 mm Hg. Diagnosis of NTG requiring an untreated mean diurnal IOP of over 21 mm Hg from diagnosis to enrollment, indicated by the patient chart. Ocular hypertension is defined as a condition in which the IOP was greater than 21 mm Hg in the absence of glaucomatous defects in visual field testing, the normal appearance of the optic disc and nerve fiber layer, anatomic normality, open angles in gonioscopy, and the absence of ocular conditions contributing to the elevation of pressure, such as narrow angles, neovascular conditions, and uveitis.
• Adult Patients (over 18 years old ) diagnosed with POAG and NTG are defined as those with open normal appearing angles, typical glaucomatous optic atrophy (i.e., neural rim thinning, notching, saucerization, or nerve fiber layer disc haemorrhage), and typical glaucomatous visual field damage (i.e., arcuate, paracentral scotoma, or nasal step).
• Adult Patients (age over 18 years old ):

with unilateral or bilateral open-angle glaucoma (POAG) without previous eye surgery, treated with topical anti-glaucoma medications, who need glaucoma surgery with iStent inject W. The investigators will include patients with isolate iStent surgery and patients with combined cataract and iStent surgery. In cases of bilateral glaucoma, the two eyes of the same patient may be included consecutively.

For the control group only: Patients with topical hypotensive glaucoma treatment requiring cataract surgery.

Exclusion Criteria:

• Age under 18 years
• Visual defects attributable to nonglaucomatous conditions, primary angle closure glaucoma, neovascular glaucoma, history of ocular trauma, retinal disease or ocular inflammation, and laser therapy or secondary glaucoma.
• The patients have to meet best-corrected Snellen visual acuity of under 0.3 and spherical equivalent of under 6 diopter.
• We will not include patients with previous ocular surgery, except cataract surgery performed at least 6 months prior to the inclusion date.