As long ego as 1965 Campbell and Green in their paper pointed out that plotting contrast sensitivity S on a log-scale versus spatial frequency f on a linear scale, “…high frequency portion of the curve, from 10c/deg on upwards, is closely fitted by a straight line. That is, the contrast sensitivity is decreasing exponentially with increasing spatial frequency.” An approximation S(f)=A*EXP(-k*f) depends on two parameters: A is normalizing coefficient, and k is supposed to be taken as a measure of attenuation. Contrast sensitivity function is commonly considered to be proportional to a modulation transfer function of visual system as a whole and should be a product of transfer functions of visual pathway elements. Using exponential approximations for these functions in high-frequency range with appropriate k[i], we could calculate k as a sum of k[i]. Surprisingly, we find that this approximation is not in use to analyze experimental and theoretical data concerning visual acuity. We validated the approximation with large set of our experimental data. Attenuation k between 0.09 and 0.16 was obtained with good correlation. It was shown that both theoretical and experimental transfer curves from different papers incorporating optical and retinal image distortions are well approximated by exponents.