Validation of Non-invasive Absolute Intracranial Pressure Monitoring

Inclusion Criteria: * Adult patients, age ≥ 18 years, admitted after TBI, ICH, secondary edema after stroke or SAH at the Departments of Neurosurgery or Neurology, Kantonsspital Aarau, Switzerland. * Patients under sedation and ICP monitoring * Informed consent obtained from the legally authorized representative prior initiation of the measurements. Exclusion Criteria: Age \< 18 years at study entry. * Patients with wounds, scars including the front orbital region. * Perforating or penetrating mechanism of TBI * Patients with orbital injury or abnormal blood flow in both Ophthalmic Arteries * Patients with previous retina surgery * Patients with previous cataract surgery * Patients with any known ocular condition that may be worsened by sustained eye pressure in the opinion of the subject's ophthalmologist * Patients with radiological signs of calcification or atheromatose plaques in the internal carotid artery detected by CT or angiography (performed prior and independently of the study)