title: Short-term hypobaric hypoxia enhances visual contrast sensitivity.
abstract: The effect of hypoxia on early visual functions remains a controversial area of research. To explore this question, we measured static and dynamic visual contrast sensitivity in 14 healthy volunteers at a simulated altitude of 5500 m. In comparison with the baseline condition (mean arterial oxygen saturation: 98.4%), contrast sensitivity significantly increased after 5, 10 and 15 min of hypoxic exposure (saturation: 82.9%, 77.0%, 74.3%, respectively). After 10 min, this enhancement was markedly pronounced under dynamic conditions. Returning to the baseline altitude (saturation: 97.7%), contrast sensitivity recovered, mostly at the lower spatial frequencies. There was a significant negative relationship between arterial oxygen saturation and contrast sensitivity values at low and medium spatial frequencies (0.5-4.8 c/deg). These results suggest that early visual processing may be enhanced during short-term hypoxic challenge.
authors.affiliation: University of Szeged, Department of Neurology, Aeromedical Hospital, Hungarian Defense Forces, H-6725, Semmelweis u. 6., Szeged, Hungary.
authors.forename: Krisztina
authors.initials: K
authors.lastname: Benedek
authors.forename: Szabolcs
authors.initials: S
authors.lastname: Kéri
authors.forename: Andor
authors.initials: A
authors.lastname: Grósz
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Tótka
authors.forename: Erika
authors.initials: E
authors.lastname: Tóth
authors.forename: György
authors.initials: G
authors.lastname: Benedek
mesh_terms: D000328:Adult; D001274:Atmospheric Pressure; D001921:Brain / Q000503:physiopathology*; D002560:Cerebrovascular Circulation / Q000502:physiology; D015350:Contrast Sensitivity / Q000502:physiology*; D006801:Humans; D002534:Hypoxia, Brain / Q000503:physiopathology*; D008297:Male; D010775:Photic Stimulation; D012160:Retina / Q000503:physiopathology*; D013997:Time Factors; D015854:Up-Regulation / Q000502:physiology*; D014795:Visual Pathways / Q000503:physiopathology*