Application of subjective visual otolith function test on the medical evaluation of pilots

Objective To provide the references on otolith function evaluation by investigating subjective visual vertical (SVV) and subjective visual horizontal (SVH), as well as the tilt range of SVV and SVH when pilot's head tilted 45° to the left or right side for the selection and the medical evaluation of pilots . Methods XZ-2008 Otolith function test instrument was chosen for the tests. ①One hundred active fighter pilots were chosen as the subjects and the angle range of their head upright SVV was recorded. ②Twenty-four active fighter pilots were chosen as the subjects. The angle range of their head upright SVV and the angle ranges of head 45°right or left tilt SVH and SVV were recorded. Normal value range was caculated according to Mean±1.96 SD Results ①The angle range of head upright SVV of 100 pilots was -1.61°-1.73°. ②The angle range of head upright SVH of 24 pilots was -2.34°-3.18°, the angle range of head 45° left tilt SVV was -7.12°-6.12°, and the range of -6.76°-4.84° for their head 45° right tilt. The angle range of 45° left tilt and 45° right tilt SVH was respectively -9.84°-6.74°, and -6.70°-6.20°. Conclusions The study has established the test method and the normal angle range of SVV and SVH in military pilots, which is crucial for the assessment of the otolith function in medical selection and medical evaluation of military pilots. When head tilts to left or right by 45° the angles of SVV and SVH will change. We will further study its clinical signification and provide more evidence for the vestibular function medical evaluation of military flying personnel. Key words: Vestibule; Visual; Otolith membrane; Saccule and Utricle; Eligibility determination; Pilot