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March 1954


AMA Arch Ophthalmol. 1954;51(3):343-355. doi:10.1001/archopht.1954.00920040349008

ONE OF the consequences of flying at high velocities is that changes in direction or speed may produce profound physiological effects in the pilot. These accelerative forces are known as g forces (expressed as multiples of the gravitational attractive force). Depending upon how the force is vectored through the body of the subject, it is referred to as a positive, negative, or transverse g force. Military maneuvers, such as gunnery and dive bomb runs and steep inside turns, produce a characteristic group of symptoms culminating in black-out and unconsciousness which are known collectively as the physiological effects of positive g.*

Many authors use the words "black-out" and "unconsciousness" interchangeably. In an effort to counteract this semantic error, the term amaurosis fugax has been substituted as a more accurate and all-inclusive description.† However, this is not fully warranted, because clinically amaurosis fugax refers to a temporary loss of vision, such as