Medical research

Researchers uncover mechanism blocking retina regeneration

A discovery opens the possibility of one day restoring loss of vision by activating the retina's ability to regenerate. Researchers at Baylor College of Medicine, the Cardiovascular Research Institute and the Texas Heart ...

Neuroscience

Retinal prion disease study redefines role for brain cells

National Institutes of Health scientists studying the progression of inherited and infectious eye diseases that can cause blindness have found that microglia, a type of nervous system cell suspected to cause retinal damage, ...

Ophthalmology

What you need to know about wet macular degeneration

Millions of people deal with age-related macular degeneration as they get older, but many don't understand the difference between types of the condition or what they can do to lessen the effects. Dr. Sophie Bakri, a Mayo ...

Alzheimer's disease & dementia

Evidence mounts that an eye scan may detect early Alzheimer's disease

Results from two studies show that a new, non-invasive imaging device can see signs of Alzheimer's disease in a matter of seconds. The researchers show that the small blood vessels in the retina at the back of the eye are ...

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Retina

The vertebrate retina is a light sensitive tissue lining the inner surface of the eye. The optics of the eye create an image of the visual world on the retina, which serves much the same function as the film in a camera. Light striking the retina initiates a cascade of chemical and electrical events that ultimately trigger nerve impulses. These are sent to various visual centers of the brain through the fibers of the optic nerve.

In vertebrate embryonic development, the retina and the optic nerve originate as outgrowths of the developing brain, so the retina is considered part of the central nervous system (CNS).. It is the only part of the CNS that can be imaged non-invasively in the living organism.

The retina is a complex, layered structure with several layers of neurons interconnected by synapses. The only neurons that are directly sensitive to light are the photoreceptor cells. These are mainly of two types: the rods and cones. Rods function mainly in dim light and provide black-and-white vision, while cones support daytime vision and the perception of colour. A third, much rarer type of photoreceptor, the photosensitive ganglion cell, is important for reflexive responses to bright daylight.

Neural signals from the rods and cones undergo complex processing by other neurons of the retina. The output takes the form of action potentials in retinal ganglion cells whose axons form the optic nerve. Several important features of visual perception can be traced to the retinal encoding and processing of light.

This text uses material from Wikipedia, licensed under CC BY-SA