Abstract
Purpose: :
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
Methods: :
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)
Results: :
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.
Conclusions: :
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.
Keywords: oxygen • blood supply • computational modeling