THE EFFECTS OF EXPOSURE TO SMALL QUANTITIES OF CARBON MONOXIDE ON VISION

This paper discusses the results of experiments on the effects of small amounts of carbon monoxide (CO) on visual perception. The quantities of CO inhaled during these studies varied from 25 to 100 ppm in the inspired air. The tests of visual perception involved measurements of both central (cones) and peripheral (rod) vision during 20-30 minutes of dark adaption. Also, tests for differential light sensitivity were made on foveal vision and on vision acuity. Discussed are studies of light sensitivity and dark adaption in relation to hypoxia, the role of oxygen want in the aging process, the role of CO in accentuating the effects of high altitude, and the effects of CO on light sensitivity. It was concluded that recovery from the detrimental effects of CO on visual function lags behind the elimination of CO from the blood. This impairment appears to be determined by the duration and concentration of the CO. The time course followed by the COHb and visual impairment appears to depend on the composition of the gas during the postanoxic period. Carbogen was 2.5 times more effective than 100% oxygen in promoting CO elimination and an associated drop in the visual threshold. Subsequent exposure to room air caused an increase in the visual threshold, although the COHb levels began to fall. A hypothesis is the existence in the central nervous system or visual system of some enzyme or other vitally important constituent which combines competively with CO and carbon dioxide./SRIS/