Fovea

A small depression or pit in the center of macula lutae of the retina, and thus referred to as the fovea centralize or central fovea.  The macula (also called the macula retinae or the spot of Soemmering) is a minute oval-shaped yellowish area (and thus sometimes referred to as the yellow spot) about 2.5 mm in diameter having a field of view of 8 degrees and a 5:2 ratio of cones to rods.  The fovea is 1.5 mm wide and densely packed with cones (about 6 million in the human eye), with a field of vision of about 5 degrees.  Here, the layers of the retina are spread aside so that light falls directly on these photoreceptors, thus providing the sharpest central (diurnal) vision or visual acuity as well as colour vision. Unlike the peripheral retina that possesses greater sensitivity to dim light (known as the Arago phenomenon) and motion of objects and events in the environment, it has no blood vessels.  Developmentally, the fovea is the last part of the retina to mature, with a thickening of the ganglion cell layer beginning during mid-gestation (i.e., about 22 weeks gestational age).  The outer nuclear layer, which is wider than elsewhere in the retina, consists almost entirely of developing cone cells.  The nuclei of these cells migrate radially outward in a circle, leaving the fovea nuclei-free.  By one week after birth, a shallow foveal pit can be identified.  The foveal cones alter shape to accommodate the movement of ganglion cells, and continue to do so along with further cell-to-cell connections, until about 4 years of age. 

See Cones and rods, Eye movements, Ganglia, Optic nerve, Overt attention, Retina, Visual acuity