At the back of the human eye, the retina serves the essential function of receiving visual information from the environment and transferring it to the brain. The external layer of the retina consists of photoreceptive cells, which collect light and pass it toward the rear of the retina, where structures known as rods and cones start communication with the brain.
Rods are primarily responsible for low-light photoreception, while cones support color and daytime vision. The densest concentration of cones is present in the fovea, defined as the 3 millimeter area located at the very center of the macula. In this region, which is the thinnest of the retina, light strikes directly and provides a high level of visual precision.
The rods and cones serve to transmit light through a series of synapses, each of which is oriented either vertically or horizontally to the retinal surface. This process terminates in the axions of the ganglion cells, which converge at an area known as the optic disc. Here, the ganglion cell axions carry signals to the lateral geniculate nucleus of the brain stem, where the brain interprets the resultant signal into something recognizable as an image.