A Study on the Vestibular Function in the Pilots

Ahn, Seung Cheol; Park, Jae Beom; Kim, Sung Won

Abstract

To investigate the short-term vestibular responses in the pilots, the 4 successive velocity step tests were done on the 25 pilots, who are in active service in ROKAF (Republic of Korea Air Force), and the obtained results were compared with those of the non-pilots. As the repeated rotations might alter the vestibulo-ocular reflex (VOR), sinusoidal harmonic acceleration (SHA) test at a frequency of 0.16 Hz were also given before and after the 4 successive velocity step tests to investigate the changes of gain and phase of VOR. In the 25 pilots (mean age 31 year), the mean values of the slow cumulative eye position (SCEP), the time integral of eye velocity during nystagmus and time constants were gradually reduced with 4 successive trials. These values were significantly greater than those obtained in the 25 non-pilots. The gain of vestibulo-ocular reflex (VOR) induced by SHA test at a frequency of 0.16 Hz decreased from 0.64+/-0.04 to 0.58+/-0.03 in the pilots, while the VOR gain increased from 0.59+/-0.03 to 0.78+/-0.06 in the non-pilots. However, this result did not indicate that the pilots' gains of VOR were out of normal range. In another SHA tests in which the 30 pilots participated, the gains, phases and the symmetries of VOR lied in the very normal range in every test frequencies (0.01, 0.02, 0.04, 0.08, 0.16, 0.32 Hz). From the above results, it might be suggested that the vestibular responses of the pilots are different with those of the non-pilots.