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Cones in the Fovea are susceptible to three colors: blue spectrum (440-480 nm), green (510-550 nm) and red (620-770 nm). The foveola (2.2 mm diameter) consists from only red and green cones. Dark blue cones are found inside the rings located around the foveola, with an outside diameter of approximately 4.5 mm (stereo-angle of 180o). The density of blue cones within this ring has the highest concentration . This ring apparently plays a leading role in the physiological mechanism of aiming the eye for the highest accuracy of the image (fig. 1).