摘要： BACKGROUND: The exoscope has been reported as a novel neurosurgical instrumentation in clinical practice. OBJECTIVE: To investigate the possibility that ORBEYE (OE), a novel instrument that excludes eyepiece lenses and allows for microsurgery by observation of the 4K3D monitor, could replace microscopes. METHODS: We report 22 clinical cases by 5 experienced neurosurgeons and the comparative results of training 10 residents. An observation study with questionnaire survey was conducted on usability. Twelve items including image quality, eyestrain, and function of the arm were evaluated. RESULTS: The following 22 clinical procedures were conducted: surgery for intracranial hemorrhage (n = 2) and brain tumor (n = 8), laminectomy (n = 3), aneurysm clipping (n = 3), vascular anastomosis (n = 2), carotid endarterectomy (n = 2), and nerve decompression (n = 1). No complications were observed. The fluorescent study, including indocyanine-green and 5-aminolevunic acid, allowed for clear depiction on the 4K monitor. The surgeon could operate in a comfortable posture. Similar to the microscope, it was possible to change the optical and viewing axes with the OE, but the OE was switched to the microscope or endoscope in hematoma removal and pituitary surgery. Residents judged that eyestrain was strong (P = .0096). Experienced neurosurgeons acting as assistants judged that the scope arm’s range of movement was narrow (P = .0204). Sixty percent of residents judged that the OE was superior to the microscope. CONCLUSION: Although based on limited experience, it was not possible to substitute the microscope with the OE in all operations; however, the OE surpasses the microscope in terms of ergonomic features.