[Amplitude-frequency characteristics of the retina under diffuse and pattern stimulation and new formalized signs of flicker and pattern electroretinogram].

Unlabelled: The clinical sugnificance of electroretinogram interpretation depends heavily on the employed mathematical apparatus. Currently, conventional calculation of the amplitude and time parameters of electroretinogram (ERG) components and their relations (indices), as well as analysis of the frequency spectrum of the signal are becoming insufficient for interpretation of the obtained data. New approaches to diagnostics are currently being developed, using, among other things, expert systems, and neural network and simulation models.

Purpose: To obtain additional formalized signs of ERG responses to flicker and pattern stimuli by analyzing the amplitude-frequency characteristics of the retina.

Material And Methods: A photopic flicker ERG (FERG) and a transient pattern ERG (PERG) were recorded from healthy individuals and patients with glaucoma. Using the digitized FERG and PERG signals, the amplitude-frequency characteristics of the retina were studied. The results of diffuse and structured stimulation modeling in Matlab Simulink were used to identify the characteristics of retinal responses to rhythmic and pattern stimuli.

Results: The amplitude-frequency characteristics (AFC) of the retina were obtained for the first time. They objectively reflect its ability to convert spectra of stimulating signals into spectra of recorded ERG responses. Using the results of modeling, diffuse flicker and pattern stimuli we have identified features of retinal response in Matlab Simulink. Based on a simplified simulation model, a negative component (baseline drift) was detected in a healthy person's PERG and its effect on the results of retinal AFC evaluation was investigated. Polynomial approximation procedure of retinal AFC was performed for the first time allowing the use of coefficients of approximating polynomials as new formalized signs in diagnostics.

Conclusion: AFC were shown to be an objective characteristic of retinal transfer properties, which depend on the type of stimuli acting on it, as well as on the etiology of the retinal disease.