Objective: The study aimed to determine the influence of obstructive sleep apnea syndrome (OSAS), an entity characterized by repetitive upper airway obstructions during sleep, inducing hypoxia and sleep disruption, to the visual field of human with a view to morphological and physiological aspects. Patients and methods: In a prospective controlled cohort study 32 patients with a new discovered, until now untreated, moderate up to severe obstructive sleep apnea syndrome (apnoe-hypopnoe-index >20) was compared to 32 healthy people of a control group. Intervention: Detailed ophthalmologic examination including tonometry, biomicroscopic evaluation of the anterior and posterior segment of the eye, automatic and kinetic perimetry. Evaluation of polysomnographic results in relation to ophthalmologic outcome. Main outcome measures: Comparison (t-Test) of visual field indices (MD / CPSD) and local defects frequency, optic disc changes, intraocular pressure as well as correlations between MD and polysomnography are checked. Results: Mean deviation (MD) in OSA patients is significantly reduced (-1.66/-1.62 dB; p Conclusions: OSAS seems to lead to a reduced function by rarefication of nerve tissue in retina and/or optic nerve. The term of glaucoma according to his definition is applicatively.