Features of perception of color stimuli in achromatopsia
Authors: Rychkova S. I. , Likhvantseva V. G. , Sandimirov R. I. 
Published: October 2023

Introduction. Understanding the peculiarities of perception of color images by patients with achromatopsia helps to identify and differentiate this pathology from diseases with similar clinical symptoms in time. This is becoming increasingly relevant due to ongoing developments in the field of virus vector therapy using an adeno-associated virus carrying the CNGB3 and CNGA3 genes.

Purpose: to investigate the features of perception of color images by patients with achromatopsia, using in addition to the generally accepted developed proprietary tests to quantify the brightness of perceived images.

Materials and methods. Five school-age patients (12–17 years) with complete achromatopsia were observed. The control group included 36 schoolchildren aged from 10 to 17 (av. 13.4 ± 0.5) with a normal state of visual functions. The ophthalmological examination included standard research methods. In children with achromatopsia, OСT data and ERG indicators were taken into account. To study color vision in all children, the following methods were used: E.B. Rabkin’s polychromatic tables, Neitz Test, Farnsworth–Munsell Dichotomodus D-15 Test, a study of the field of vision for white and colored stimuli (on the perimeter of PNR-03). In addition, in children with achromatopsia, the perception of color stimuli with achromatic stimuli was compared using special proprietary images.

Results. Comparison of the results of the study of color vision in patients with achromatopsia in different ways demonstrates the greatest probability of diagnostic errors when using polychromatic tables, which may be due to the ability of these patients to distinguish test figures in some tables based on brightness contrast, rather than contrast of color tones. Increased sensitivity of photoreceptors to short-wave (blue part of the spectrum) radiation and significantly reduced sensitivity to short-wave (red part of the spectrum) in patients with achromatopsia may cause the expansion of the boundaries of the field of view to green and blue stimuli (while the boundaries of the field of view to the blue stimulus almost reach the values for the white stimulus), as well as a significant narrowing to red stimuli compared with the indicators in the control group (p < 0.001). The developed own test images made it possible to quantify the brightness of chromatic stimuli perceived by patients with achromatopsia in comparison with the brightness of achromatic stimuli. The brightest (90–100%) for them was the blue stimulus and practically merged with the white background of the screen. The red stimulus was perceived to be the darkest (minimum brightness). Based on the data obtained, an approximate model of the perception of color images in achromatopsia was created. Conclusion. The obtained data complement the existing ideas about the peculiarities of perception of color images by patients with achromatopsia and can be used to develop new and improve existing methods of diagnosing this disease, as well as to create recommendations for the design of illustrative, educational and advertising material.