Obtaining the Amplitude-Frequency Response of the Retina and Formalization of its Parameters for Using in Diagnostic Systems

Abstract

We consider two problems in this work. The first is the justification for the possibility of obtaining the amplitude-frequency response (AFR) of the retina by processing rhythmic electroretinograms (RERG). The second problem is to approximate the obtained AFR of the retina in order to obtain additional formalized features of the current state of the retina in the form of the coefficients of the approximating polynomials. When we obtain the AFR of the eye retina, we take into consideration the spectrum of the input testing signal (stimulus). Light stimuli are periodically repeated short rectangular light pulses of five standard frequencies. Due to the fact that the retina is a nonlinear dynamic object, the changes in the AFR of the retina are evaluated and taken into consideration in the obtaining of the frequency characteristics for each frequency of light flashes. For the polynomial approximation of the obtained AFR's of the retina, it is proposed to distinguish two frequency ranges: the low-frequency range (from 0 to 50 Hz) and the high-frequency range (from 50 to 120 Hz). In the low-frequency range it is proposed to smooth the retinal AFR by the second degree polynomial smoothing, and in the high-frequency range - by the first degree polynomial smoothing. The proposed approximation of the frequency response allows to obtain 25 additional features from five experimentally determined AFR's for one person. In this case each AFR is characterized by five coefficients of smoothing polynomials. The results of the work allow us to compare different methods of classification (diagnosis) with using the received features.