A) The effect on M-cone modulation of changing the focal plane, as a function of spatial frequency, when the eye is affected by LCA. M-cone contrast is only shown for the normal M-cone pigment (M-cone extinction spectrum with a peak at 530 nm). M-cone contrast depends critically on the plane of focus, being maximal at focal planes that lie close to the peak of the M-cone extinction spectrum. B) The effect on M-cone contrast of shifting the peak of the M-cone extinction spectrum, as a function of spatial frequency, when the eye is affected by LCA, and focused to maximize luminance contrast. M-cone modulation is maximal for the normal M-cone pigment (peak at 530 nm).