Inclusion Criteria:  patient who have undergone combined phacoemulsification surgery and insertion of at least one iStent® for chronic open-angle glaucoma in the ophthalmology department of the Amiens University Hospital or the Saint-Quentin University Hospital (iStent® group). patient who have undergone simple phacoemulsification surgery in a patient with chronic open-angle glaucoma in the ophthalmology department of the Amiens University Hospital (control group). patient with Chronic open-angle glaucoma confirmed by gonioscopic examination, visual field, optical coherence tomography of the optic nerve, fundus examination, pachymetry and intraocular air pressure and/or applanation.  Exclusion Criteria:  acute angle closure glaucoma, chronic angle closure glaucoma, uveitic glaucoma, traumatic glaucoma, exfoliative glaucoma. Previous filtering surgery on the operated eye. Intraoperative complication.