Anoxia Cataract.

Abstract

The most vital requirement of tissue is an adequate supply of oxygen. Tissues possessing a blood supply are bathed in a medium containing 13 to 19 vol. % oxygen. This large amount is made possible by the hemoglobin of the red cells which holds the oxygen in a loose chemical combination. The amount of oxygen in physical solution in the body fluids is extremely small. For example, the aqueous humor has only from 0.08 to 0.12 vol. % oxygen (Friedenwald and Pierce 1 ). The necessary rapid replenishment of aqueous oxygen is made possible by rapid diffusion from the ciliary body (Pierce, Friedenwald and Freeman, 2 and Friedenwald and Pierce 1 ), and by the passage of oxygen from the atmosphere through the cornea (Fischer 3 ). From these considerations it is not surprising that there should be adverse effects upon the lens because of a lack of oxygen, an assumption substantiated by our experiments.

Biozzi 4 reported the effects of asphyxia on rats placed singly into 3-liter bell jars. He noted the development of cataract in some of these animals and subsequent regression after a short time in the fresh air.

Experimental. We undertook investigations to determine whether anoxia alone would produce cataract. Rats were placed in a steel chamber in which the pressure was gradually reduced until it was equal to that at an altitude of 30,000 feet or more. When the conditions were severe enough so that 50% of the animals died, about 75% of the dead animals and about 10% of the surviving animals had lens opacities. That the cataracts were due to anoxia and not to pressure was demonstrated by placing rats singly in glass chambers arranged so as to permit the constant flow of a mixture of gases consisting of 5% oxygen and 95% nitrogen at sea level. Again, the rats showed lens opacities. These experiments indicate that cataracts can develop in anoxia and that asphyxia and pressure are not important factors.