Macula

The macula or macula lutea (from Latin macula, "spot" + lutea, "yellow") is an oval-shaped highly pigmented yellow spot near the center of the retina.

It has a diameter of around 6 mm and is often histologically defined as having two or more layers of ganglion cells. Near its center is the fovea centralis, a small pit that contains the largest concentration of cone cells in the eye and is responsible for central, high resolution vision. The macula also contains the parafovea and perifovea.

In the macula lutea the nerve fibers are wanting as a continuous layer, the ganglionic layer consists of several strata of cells, there are no rods, but only cones, which are longer and narrower than in other parts, and in the outer nuclear layer there are only cone-granules, the processes of which are very long and arranged in curved lines. In the fovea centralis the only parts present are (1) the cones; (2) the outer nuclear layer, the cone-fibers of which are almost horizontal in direction; (3) an exceedingly thin inner plexiform layer. The pigmented layer is thicker and its pigment more pronounced than elsewhere. The color of the macula seems to imbue all the layers except that of the rods and cones; it is of a rich yellow, deepest toward the center of the macula, and does not appear to be due to pigment cells, but simply to a staining of the constituent parts.