V. The Effect of Altitude on Ocular Functions

The examination of the aviators for the Air Service of the United States is much more strict than that of any other nation.In spite of the careful examination that eliminates men with manifestly imperfect eyes, fliers sometimes exhibit marked derangement of the ocular functions under the stress of flying and the con- ditions connected with it.In all articles pertaining to the selection of aviators, from the Allies or from alien countries, normal vision is considered to be the chief requisite.Surgeon H. Fig. î.-Effect of lack of oxygen on visual acuity, showing decrease during test on rebreathing apparatus.Graeme Anderson of the Royal Naval Service and adviser to the British Air Medical Service, in a discus- sion of the physical qualifications of fliers, says, "Prac- tically every one of the physicians and officers taking part in the discussion agreed that the function of vision was of the greatest importance."With this in mind, visual acuity under oxygen depletion, as compared with the behavior of this function under normal oxygen supply, has been studied with the aid of the Ives visual acuity test object, Snellen's type and Johnson's apparatus.It was soon found that Snellen's type and similar test objects were unsatisfactory for use with the rebreathing apparatus and that the observations thus made were inconclusive.The accompanying tabulation .gives the results of visual tests made on thirty-three subjects on the rebreathing apparatus and in the low- pressure chamber, with the aid of the Ives instrument.From the Medical Research Laboratory, A[ill]Service, Mineola, L. I.The subjects are classified as normal and subnormal, that is, those who, so far as the eyes are concerned, would pass the examination for the flying corps and those who would be ocularly disqualified.