Biomaterial Database

Laser Doppler measurement of relative blood velocity in the human optic nerve head. 1982

C E Riva, and J E Grunwald, and S H Sinclair

The Doppler shift frequency spectrum (DSFS) of laser light scattered from red blood cells (RBCs) moving in the microcirculation of the optic nerve head has been recorded in normal volunteers by means of a fundus camera laser Doppler velocimeter. The width of the DSFS, which varies in proportion to the speed of the RBCs, has been characterized by a parameter alpha. With the use of a model for the scattering of light by tissue and RBCs and for the RBC velocity distribution, values of alpha recorded at normal intraocular pressure (IOP) suggest that the RBCs that contribute to the Doppler signal are flowing in capillaries. The parameter alpha was found to vary markedly with the IOP and with the phase of the ocular pressure pulse at elevated IOP. The return of the speed of RBCs toward normal, which is observed after a step increase of IOP above normal and after a step decrease below normal, has been attributed to an autoregulatory response of the optic nerve circulation.

UI	MeSH Term	Description	Entries
D007429	Intraocular Pressure	The pressure of the fluids in the eye.	Ocular Tension,Intraocular Pressures,Ocular Tensions,Pressure, Intraocular,Pressures, Intraocular,Tension, Ocular,Tensions, Ocular
D007834	Lasers	An optical source that emits photons in a coherent beam. Light Amplification by Stimulated Emission of Radiation (LASER) is brought about using devices that transform light of varying frequencies into a single intense, nearly nondivergent beam of monochromatic radiation. Lasers operate in the infrared, visible, ultraviolet, or X-ray regions of the spectrum.	Masers,Continuous Wave Lasers,Pulsed Lasers,Q-Switched Lasers,Continuous Wave Laser,Laser,Laser, Continuous Wave,Laser, Pulsed,Laser, Q-Switched,Lasers, Continuous Wave,Lasers, Pulsed,Lasers, Q-Switched,Maser,Pulsed Laser,Q Switched Lasers,Q-Switched Laser
D008027	Light	That portion of the electromagnetic spectrum in the visible, ultraviolet, and infrared range.	Light, Visible,Photoradiation,Radiation, Visible,Visible Radiation,Photoradiations,Radiations, Visible,Visible Light,Visible Radiations
D009885	Ophthalmology	A surgical specialty concerned with the structure and function of the eye and the medical and surgical treatment of its defects and diseases.	Ocular Surgery,Ocular Surgeries,Surgery, Ocular
D009898	Optic Disk	The portion of the optic nerve seen in the fundus with the ophthalmoscope. It is formed by the meeting of all the retinal ganglion cell axons as they enter the optic nerve.	Blind Spot,Optic Disc,Optic Nerve Head,Optic Papilla,Blind Spots,Disc, Optic,Disk, Optic,Head, Optic Nerve,Nerve Head, Optic,Optic Discs,Optic Disks,Optic Nerve Heads,Optic Papillas,Papilla, Optic,Papillas, Optic,Spot, Blind
D001783	Blood Flow Velocity	A value equal to the total volume flow divided by the cross-sectional area of the vascular bed.	Blood Flow Velocities,Flow Velocities, Blood,Flow Velocity, Blood,Velocities, Blood Flow,Velocity, Blood Flow
D004301	Doppler Effect	Changes in the observed frequency of waves (as sound, light, or radio waves) due to the relative motion of source and observer. The effect was named for the 19th century Austrian physicist Johann Christian Doppler.	Doppler Shift,Effect, Doppler,Shift, Doppler
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D012542	Scattering, Radiation	The diversion of RADIATION (thermal, electromagnetic, or nuclear) from its original path as a result of interactions or collisions with atoms, molecules, or larger particles in the atmosphere or other media. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)	Radiation Scattering,Radiation Scatterings,Scatterings, Radiation