Changes of visual performance induced by exposure to whole-body vibration.

To clarify the effects of whole-body vibration (WBV) on visual performance, visual acuity and a self-rated assessment of difficulties in visible perception were determined after various frequencies of vibration in six healthy males. Two different sitting postures, an erect posture and a muscle-relaxed posture, were used. Sinusoidal vertical vibrations at ten frequencies (8, 10, 12.5, 16, 20, 25, 31.5, 40, 63.5 and 80 Hz) were applied to the seated subjects for 20 sec. The magnitude of acceleration at each vibration frequency was maintained at 2.5 msec-2 (r.m.s.). The visual performance was evaluated by a standard visual acuity test and a self-rated assessment for difficulties in visible perception. The disturbances of visual performance were dependent on the vibration frequency (p < 0.01, ANOVA) with a maximum reduction of visual acuity at a frequency of 12.5 Hz. The disruption of the visual performance was more severe with the erect posture than with the muscle-relaxed posture. In conclusion, short-term WBV exposure can affect visual performance, depending on the vibration frequency and the sitting posture. The visual acuity and self-rated assessment of disturbances of vision may be influenced by the resonance frequency of the eyeball.