Color discrimination under chronic hypoxic conditions (simulated climb "Everest-Comex 97")

Hypoxia is known to alter visual functions. In the present study, the effec ts of chronic hypobaric hypoxia upon Visual color discrimination were studi ed in 8 subjects participating in a simulated climb from sea level (PO2 = 2 10 hPa) to 8,848 m (PO2 = 70 hPa) over a 31-day period of confinement in a decompression chamber ('Everest-Comex 97'). During these investigations, th e subjects were required to discriminate between colors of different hue in the red, blue, and green ranges. Alterations in color discrimination incre ased slightly but significantly as altitude increased. Impairments occurred mainly in the red and blue ranges. In addition, our results further indica te that color discrimination would be affected only when a minimum threshol d of difference between color stimuli is not present. Methodological and ph ysiological implications are discussed.