Effect of Hypoxia on Simultaneous Visual Contrast

¹ Department of Physiology, Division of Basic Health Sciences, Emory University, Atlanta, Ga.

The effect of hypoxia on simultaneous visual contrast was studied in 7 test subjects. The contrast sensitivity was quantitated in luminace units and recorded every 10 seconds. Hypoxia was induced by having the subject breathe 10 per cent oxygen and 90 per cent nitrogen for 15 minutes. The contrast sensitivity began to decrease shortly after transition to 10 per cent oxygen and continued to decrease throughout the hypoxia period. Furthermore, the contrast sensitivity decreased markedly during the posthypoxia period and failed to return to the prehypoxia level within 10 minutes. It is concluded that inhibitory processes responsible for visual contrast phenomena are sensitive to hypoxia and are especially affected during the posthypoxia period. The effect persists much longer than the reduction of the oxygen partial pressure in the blood.