A Preliminary Study of the Assessment of Visual Space Recognition in Stroke Patients using New Head Mounted Display (HMD) System with Visual Image Transformation

Various disturbances of visual space recognition include unilateral spatial neglect (USN) and visual field defects (VFD) has been strongly associated with an increased risk for injury and with poor functional outcome. To quantitatively evaluate visual-spatial recognition in cerebrovascular disease patients, we developed a new measurement system able to present a versatile visual information. The system uses a head-mounted display (HMD) as the device that presents visual information. The purpose of this study was the development of a method for presenting diverse visual information and assessing visual space recognition using a new head mounted display (HMD) system. A total of eight subjects participated in this study, comprising four with USN and four with VFD. A test sheet was placed on a desk, and its image was projected on the display of the HMD. Then, space recognition assessment was conducted using a cancellation test and motion analysis of the eye, head and trunk movements under four conditions with images reduced in size and shifted. Leftward visual search was dominant in VFD patients, while rightward visual search was dominant in USN patients. The angular velocity of leftward eye movement during visual search of the right sheet decreased in both patient types. Motion analysis revealed a tendency of VFD patients to rotate the head in the affected direction under the left reduction condition, whereas USN patients rotated it in the opposite direction of the neglect. A new HMD system was developed for presenting diverse visual information and assessing visual space recognition which identified the differences in the disturbance of visual space recognition of VFD and USN patients were indicated. The HMD system may be available and effective for evaluating and training visual recognition and ADLs in VFD and USN patients as a clinical device.