Traumatic and nontraumatic brain injuries can cause elevated intracranial pressure (ICP), a complication that requires early recognition and management due to its associated poor prognosis. Optic nerve sheath diameter (ONSD), which can be visualized and measured utilizing ultrasonography, can reflect changes in intracranial pressure allowing early diagnosis, triaging, and management. For the neurointensivist, ONSD ultrasound can act as a tracking tool that provides a one-time measure and gives valuable information as a follow-up regarding response to therapeutic measurements.