with reflectance oximetry of the retina or ultrasound measurement of blood flow in the central retinal artery, or automate the method by adding a camera and an image processing software capable of recognizing venous pulsations from a sequence of images of the eye fundus. evaluation in patients confirmed a strong linear relationship and clinically negligible differences (2-3mmhg) between vop and the invasively measured icp. ophthalmodynamometry requires dilated pupils, a skilled physician or medic, and collaboration of the patient, which all hampers its applicability in the field. it cannot be applied in cases of ocular trauma or conditions that selectively affect the optic nerve and gives erroneously high readings in the presence of a papilledema, which may persist long after icp has returned to normal. neurolife non-invasive solutions inc. developed technology based on braxton's patent. they won purdue university's business plan competition in 2006 and were using the funds to develop iscan, its initial prototype. the approach worked on measuring icp non-invasively by assessing changes in the retinal blood flow. however this is dependent on other factors apart from icp, so it will be difficult to generate accuracy sufficient for clinical practice. third eye diagnostics, inc. is developing the cerepress™, a non-invasive, hand-held intracranial pressure monitor that gathers information from the patient's un-dilated eye. the cerepress™ measures blood pressure in the eye's central retinal vein (crv) and blood velocity in the ophthalmic artery, which taken together highly correlate to intracranial pressure. to obtain crv pressure, 3ed has developed a novel apparatus that simultaneously record images of the crv and measures intraocular pressure (iop) while the pressure in the eye is increased. a medical technician aligns the system by easily centering the field of view to patient's pupil eye. the system then contacts the patient's cornea and simultaneously collects images of the cornea and the retinal fundus. the contact force increases the iop and momentarily compresses the crv. at the instant of complete crv compression, the cerepress™ records the eye pressure, which is equivalent to crv pressure. crv pressure is a known to be a good correlate to icp. this method requires an individual patient-specific calibration as every other "correlation-based" method.