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Vasile Diaconu, Valentina Vucea; Retina Blood Oxygenation From Near Infrared Spectral-Reflectometry Measurements. Invest. Ophthalmol. Vis. Sci. 2011;52(14):2894.
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From similar principles to those of the technology developed in the field of the visible spectra (Diaconu 2009), the development of a new reflectometry technology and method in the near-infrared spectral area is proposed to derive blood oxygenation from retina vessels
The infrared reflectometry function was continuum recorded by the multi-channel technique, (800 wavelengths from 650 nm to 850 nm) from the optic nerve capillary and fovea zone, during 20 seconds with 1 second integrations to six healthy subjects. Model The mathematical equation used to derive the hemoglobin and the oxyhaemoglobin contribution spectra from the infrared reflectometry absorption function log (A () ) was expressed as a linear combination of three terms of SOHb(), SHb(), and SOH2() representing the spectral signature functions of the hemoglobin, oxyhemoglobin and water, one term -n representing scattering and a constant factor, k. A multi-Gaussian function is included in the model to compensate for the non-compatibility of the model and the experimental data in the red spectral zone. Eq. log (A () )= m1*SHb() + m2*SOHb() + m3*SOH2()+ m4* -n + m5* k - Σ (i) m5+i*N(µi,σ2)
The modeling results show that the light diffused by the heritocities represents an important contribution to the infra-red reflectometry function from retinal vessels. Consequently blood oxygenation derivation from infra-red reflectometry measurements will be able to offer less precision in comparison with blood oxygenation derived from the reflectometry function in the visible spectra.
The main advantage of this new technology is that the near-infrared radiation is not absorbed by certain structures of the retina (photo-pigment, pigment epithelium) etc. Consequently the infrared reflectometry technique will facilitate measurements of blood oxygenation from retina zones like the fovea and choroid.
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