Helmet or Head-Mounted Displays (HMD) applications have expanded to include a range from advanced military cockpits to consumer glasses. However, users have documented loss of legibility while undergoing vibration. Recent research indicates that undesirable eye movement is related to the vibration frequency a user experiences. In vibrating environments, two competing eye reflexes likely contribute to eye movements. The Vestibulo-ocular Reflex responds to motion sensed in the otoliths while the pursuit reflex is driven by the visual system to maintain the desired image on the fovea. This study attempts to isolate undesirable eye motions that occur while using a HMD by participants completing simple visual tasks while experiencing vertical vibration at frequencies between 0 and 10 Hz. Data collected on participants head and helmet movements, vibration frequency, acceleration level, and visual task are compared to eye movements to develop a method to understand the source of the unintended eye movements. Through the use of Electro-Oculography (EOG) eye movements were largest when a 4 Hz vibration frequency was applied, and are significantly different from the EOG signal at 2, 8 and 10 Hz. Stepwise regression indicated that head pitch acceleration and helmet slippage pitch acceleration were correlated with EOG values.