The retina is the back part of the eye that contains the cells that respond to light. These specialized cells are called photoreceptors. ... The rods are most sensitive to light and dark changes, shape and movement and contain only one type of light-sensitive pigment. Rods are not good for color vision. The retina (from Latin: rēte) is the innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs. The optics of the eye create a focused two-dimensional image of the visual world on the retina, which translates that image into electrical neural impulses to the brain to create visual perception. The retina serves a function analogous to that of the film or image sensor in a camera. The neural retina consists of several layers of neurons interconnected by synapses and is supported by an outer layer of pigmented epithelial cells. The primary light-sensing cells in the retina are the photoreceptor cells, which are of two types: rods and cones. Rods function mainly in dim light and provide black-and-white vision. Cones function in well-lit conditions and are responsible for the perception of colour, as well as high-acuity vision used for tasks such as reading. A third type of light-sensing cell, the photosensitive ganglion cell, is important for entrainment of circadian rhythms and reflexive responses such as the pupillary light reflex.
Light striking the retina initiates a cascade of chemical and electrical events that ultimately trigger nerve impulses that are sent to various visual centres of the brain through the fibres of the optic nerve. Neural signals from the rods and cones undergo processing by other neurons, whose output takes the form of action potentials in retinal ganglion cells whose axons form the optic nerve.[1] Several important features of visual perception can be traced to the retinal encoding and processing of light.
In vertebrate embryonic development, the retina and the optic nerve originate as outgrowths of the developing brain, specifically the embryonic diencephalon; thus, the retina is considered part of the central nervous system (CNS) and is actually brain tissue. It is the only part of the CNS that can be visualized non-invasively. Ever since you were little, you’ve been hearing lots of hearsay about your eyes and how to keep them healthy. Are carrots really good for your eyes, and will they help you see in the dark? Will reading fine print at night make your eyesight go bad? While many of these are based in fact, they aren’t entirely true. Let’s try to sort the fact from the fiction.
Damage Versus Fatigue
Many of these eye myths involve the threat of damage to your eyes. You may have heard that reading in dim. The retina is an essential part of the eye that enables vision. It's a thin layer of tissue that covers approximately 65 percent of the back of the eye, near the optic nerve. Its job is to receive light from the lens, convert it to neural signals and transmit them to the brain for visual recognition.
