The method of measurements of the blood's biophysical parameters by data of photometric measurements of a capillary with blood is considered. Method takes into account the absorption of light by hemoglobin, its derivatives and degradation products, as well as the scattering of blood cells. The regression approach to determining of biophysical parameters of retina by measurements of it's reflectance spectra is proposed. A set of wavelengths of the scattered radiation, which are the most informative about concentration of haemoglobin and oxygen saturation of blood in retina, are established. The equations of regression between spectral values of reflectance and required parameters of retina are obtained.