 This clinical project will include OSA patients with the following inclusion criteria: OSA defined by a respiratory-disturbance index 15hour number of episode of partial hypopnea or complete apnea upper airway obstruction, age between 18 and 80 years, affiliation to the health care system. The exclusion criteria are: ocular disease including cataract or retinal disease, ametropia 3 diopters, optic neuropathy other than NAION in group 2, uncontrolled high blood pressure, cardiovascular treatment vasoconstrictors, vasodilatators, beta and alpha agonists or antagonists, nitric derived medication, corticosteroids, theophylline, sildenafil, immunosuppressors, neuroleptics, non steroid anti inflammatory, oestroprogestative treatment, hypnotics benzodiazepines, local treatment for ocular hypertension or glaucoma. 