An apparatus for non-invasively determining the absolute value of intracranial pressure of a living body comprising: a Doppler device for concurrently and noninvasively generating intracranial velocity and extracranial velocity signals representative of measured velocities of blood flow in an intracranial segment and extracranial segment, respectively of an ophthalmic artery extending from inside the cranium into an eye of the living body; a scan-mode processing unit for noninvasively locating the intracranial and extracranial portions of an ophthalmic artery extending from inside the cranium into the eye; a device for applying an external pressure against said eye and measuring and storing the applied external pressure; a spectral mode processing unit (1.7) adapted to generate an intracranial velocity spectrogram from said intracranial velocity signal and an extracranial velocity spectrogram from said extracranial velocity signal; a pulse wave spectrogram processing unit adapted to separate said intracranial velocity spectrogram and said extracranial velocity spectrogram into separate heart cycle spectrograms for individual heart cycles, aligning said heart cycle spectrograms for each heart cycle by cross-correlation, and calculating a maximum intracranial velocity envelope and a maximum extracranial velocity envelope by coherent averaging of a set of spectrograms representative of multiple heart cycles; and an absolute intracranial pressure calculation unit adapted to: measure intracranial blood flow pulsation parameters and extracranial blood flow pulsation parameters from the maximum intracranial and extracranial velocity envelopes, respectively; calculate intracranial and extracranial angle-independent blood flow factors from said intracranial blood flow pulsation parameters and extracranial blood flow pulsation parameters; and identify the absolute value of the intracranial pressure as that extracranial pressure which causes the ratio of the intracranial angle-independent blood flow factor to the extracranial angle-independent blood flow factor to be equal to 1. a Doppler device for concurrently and noninvasively generating intracranial velocity and extracranial velocity signals representative of measured velocities of blood flow in an intracranial segment and extracranial segment, respectively of an ophthalmic artery extending from inside the cranium into an eye of the living body; a scan-mode processing unit for noninvasively locating the intracranial and extracranial portions of an ophthalmic artery extending from inside the cranium into the eye; a device for applying an external pressure against said eye and measuring and storing the applied external pressure; a spectral mode processing unit (1.7) adapted to generate an intracranial velocity spectrogram from said intracranial velocity signal and an extracranial velocity spectrogram from said extracranial velocity signal; a pulse wave spectrogram processing unit adapted to separate said intracranial velocity spectrogram and said extracranial velocity spectrogram into separate heart cycle spectrograms for individual heart cycles, aligning said heart cycle spectrograms for each heart cycle by cross-correlation, and calculating a maximum intracranial velocity envelope and a maximum extracranial velocity envelope by coherent averaging of a set of spectrograms representative of multiple heart cycles; and an absolute intracranial pressure calculation unit adapted to: measure intracranial blood flow pulsation parameters and extracranial blood flow pulsation parameters from the maximum intracranial and extracranial velocity envelopes, respectively; calculate intracranial and extracranial angle-independent blood flow factors from said intracranial blood flow pulsation parameters and extracranial blood flow pulsation parameters; and identify the absolute value of the intracranial pressure as that extracranial pressure which causes the ratio of the intracranial angle-independent blood flow factor to the extracranial angle-independent blood flow factor to be equal to 1. measure intracranial blood flow pulsation parameters and extracranial blood flow pulsation parameters from the maximum intracranial and extracranial velocity envelopes, respectively; calculate intracranial and extracranial angle-independent blood flow factors from said intracranial blood flow pulsation parameters and extracranial blood flow pulsation parameters; and identify the absolute value of the intracranial pressure as that extracranial pressure which causes the ratio of the intracranial angle-independent blood flow factor to the extracranial angle-independent blood flow factor to be equal to 1.