Development of a Non-invasive Negative Ophthalmodynamometer Capable of Measuring Intracranial Pressure in Humans

Measurement of intracranial pressure (ICP) is essential in the diagnosis and management of numerous life threatening conditions. All current methods used clinically to measure ICP are invasive and require direct access to the cerebrospinal fluid giving them a significant side effect profile. The ability to measure ICP non-invasively would be a major milestone for patients. Spontaneous venous pulsations (SVPs) in the human eye are caused by differences in the intraocular (IOP) and intracranial pressure. The IOP at which SVPs cease is termed the venous pulsation pressure (VPP), and is equivalent to the ICP. Negative ophthalmodynamometry can measure VPP by lowering the intraocular pressure to the point in which the SVPs cease and the retinal veins dilate and has thus far been impossible to consistently perform due to the inability to quickly and non-invasively lower the IOP. The applicants have developed a novel, highly portable device that is able to lower the IOP and measure the VPP in a safe, rapid, non-invasive manner. We have successfully shown that we can measure VPP in humans with our device. The proposed study will compare ICP measured with our device with the measurement obtained from human volunteers undergoing lumbar puncture the same day.