The relationship of intraocular pressure to intracranial pressure

The early detection of intracranial hypertension can lead to timely medical and neurosurgical intervention, preventing brain herniation and death. In this investigation, we hypothesize that an increase in intracranial pressure can be detected by an increase in intraocular pressure using noninvasive existing technology, the handheld tonometer. This was a prospective observational pilot study conducted at a community hospital. Admitted patients with an invasive intracranial pressure monitor were solicited for participation. Patients were excluded if they had known glaucoma or had sufficient ocular or facial trauma that precluded intraocular pressure determination. Simultaneous measurements of intracranial and intraocular pressure were recorded. Twenty-seven patients were enrolled, and 76 individual measurements were performed. All patients with an abnormal intracranial pressure had an abnormal intraocular pressure; similarly, all patients with a normal intracranial pressure had a normal intraocular pressure (sensitivity 1.00, 95% confidence interval 0.86 to 1.0; specificity 1.0, 95% confidence interval 0.93 to 1.0) Abnormal intraocular pressure as measured with the handheld tonometer is an excellent indicator of abnormal intracranial pressure in patients with known intracranial pathology.