METHOD AND DEVICE FOR EVALUATING BLOOD SUPPLY OF STRUCTURES OF EYE BOTTOM Russian patent published in 1995 - IPC

FIELD: medicine; ophthalmology. SUBSTANCE: eye bottom is illuminated by light flux in two spectral ranges, one of which corresponds to minimal and the other one - to maximal absorption of light by hemoglobin of blood. Light fluxes after being reflected from eye bottom are converted into electric signals and relations of these signals are determined. During process of cure the relation of electric signals are determined as relation of amplified value of difference of electric signals which correspond to reflected light fluxes with minimal and maximal light absorption by hemoglobin of blood, to corresponding reflected light flux with maximal light absorption by hemoglobin of blood. In this case zero value of difference of electric signals is set before cure by means of changing factors of conversion of reflected light fluxes into electric signals. Difference of electric signals after cure is determined at values of conversion coefficients of reflected light fluxes after cure. Value of signal difference is then amplified and relation of this difference to electric signal is determined which corresponds to reflected light flux with maximal light absorption by hemoglobin of blood at initial conversion coefficient. Changes in blood supply are evaluated according to value achieved. Device for evaluation of blood supply of structures of eye bottom has illumination-projection unit, ophthalmoscope, optical divider mounted at output of the ophthalmoscope. Light filter with bandwidth which corresponds to maximal absorption of light by hemoglobin, the first photodetector and the first signal change registrar; all the units are connected in series, moreover, the filter is mounted at the first output of the optical divider. Light filter mounted at the second output of the optical divider has bandwidth corresponding to maximal absorption of light by hemoglobin, is connected in series with the second photodetector and the second signal change registrar and controlled transmission gain amplifier. Output of the amplifier is connected to input of differential amplifier. The second input of the differential amplifier is connected with output of the first signal change registrar. Output of the differential amplifier is connected to input of the first sample-store unit. Output of the latter is connected to output of the second signal change registrar. Output signal registrar is connected with output of relation meter. Device also has comparison standard and control pulse former. EFFECT: improved precision of evaluation. 2 cl, 1 dwg