Venous opthalmodynamometry: a noninvasive method for assessment of intracranial pressure

The goal of this study was to examine the potential use of ophthalmodynamometry in the noninvasive assessment of intracranial pressure (ICP). Under normal conditions, pressure within the central retinal vein is equal to or greater than ICP, because the central retinal vein basses through the optic nerve before it drains into the cavernous sinus. The optic nerve sheath is the place where ICP affects retinal venous pressure. Suction ophthalmodynamometry is an established method of investigation in ophthalmology to determine the pressure of the central retinal artery. Although observations of papilledema and lack of venous pulsations are commonly used to provide a vague assessment of ICP, ophthalmodynamometry may be used to determine the pressure of the central retinal vein. This venous pressure has never been compared with ICP.

In this study the pressure of the central retinal vein was recorded in 22 patients who underwent continuous simultaneous registration of ICP for various reasons, mainly for suspected hydrocephalus. A comparison of the two pressures was made. The results indicated a highly significant linear correlation between central retinal vein pressure and ICP. These results are of great practical value because up-to-date reliable ICP monitoring has only been possible by using invasive means, by placing a probe extradurally or subdurally into the brain parenchyma or a ventricle.

Ophthalmodynamometry can be relevant for momentary assessment and is not suitable for continuous monitoring. However, this technique can easily be repeated and may be used whenever increased ICP is suspected in a patient suffering from hydrocephalus, brain tumors, or head injury.