The glycocalyx is a fibrillary lining structure that covers the inner surface of blood vessels. Composed of glycoproteins and polysaccharides, it is an essential determinant of vascular endothelial physiology: it limits coagulation activation and adapts capillary perfusion. Studies have shown glycocalyx alteration in various vascular and autoimmune pathologies such as diabetes, high blood pressure, chronic renal failure, ischemic heart disease, stroke, dementia, septic shock, and several other inflammatory pathologies with a common basis in vascular insufficiency.

Glaucoma is a progressive, chronic and asymptomatic optic neuropathy characterized by visual field damage and abnormalities of the optic nerve head. Two hypotheses have been proposed as a basis for this progressive damage:

• the mechanical theory, which explains the papillary excavation by a compression of the optic nerve head under the effect of high intraocular pressure; and
• the ischemic theory, explained by a circulatory insufficiency at the level of the blood capillaries of the retina and especially of the optic nerve head. This latter theory is related to several pathologies that have circulatory insufficiency as common underlying pathophysiology, and in which damage to the glycocalyx has been well studied.

Glycocalyx damage has rarely been studied in glaucoma. Yang et al. showed that the glycocalyx, present in Schlem's canal, plays a major role in the transduction of shear stress and regulation of outflow resistance to the aqueous humor, which may constitute an interesting biomarker for glaucomatous pathologies.

This study propose to extend the exploration of the ischemic theory of glaucoma by a specific imaging technique (the GlycoCheck) which allows an assessment of the microvascular system integrity by giving a "vitality score" of this system. This score, known as the MicroVascular Health score (MVHS), depends on the following measured parameters: Capillary density (CD), Red blood cell filling Percent (RBF), and Perfused boundary region (PBR).

Inclusion Criteria:

• Express consent to participate in the study
• Only for case group: primary open angle glaucoma (defined as the presence of visual field damage attributed to glaucomatous optic neuropathy) in both eyes
• Only for control group: Absence optic nerve pathology (including primary open angle glaucoma)

Exclusion Criteria:

• Pregnant or breastfeeding woman
• Sleep apnea
• Renal insufficiency
• Parkinson's disease
• Alzheimer's disease
• Antiphospholipid syndrome
• Cancer for which treatment ended less than 2 years ago
• Stroke less than 1 year ago
• Myocardial infarction less than 1 year ago

Case group: patients with primary open angle glaucoma Control group : patient with no optic nerve pathology, matched with patients in case group on age (± 10 years), sex (male/female), and smoking status (active smoker/non-smoker or non-smoker or former smoker who had quit smoking for more than 6 months).