Pub. date: 2008 | Online Pub. Date: September 15, 2008 | DOI: 10.4135/9781412963954 | Print ISBN: 9781412959087 | Online ISBN: 9781412963954| Publisher:SAGE Publications, Inc.About this encyclopedia
IN THE BACK of the eye exists a thin layer of neural cells that convert external light into neural signals, known as the retina. This consists of many neuronal types, but the rods are mainly responsible for detecting low levels of light and the cones can detect different wavelengths (color). Other types of neuron connect back to the brain (retinal ganglion cells) and transmit signals from the rods and cones into the processing region of the cortex, and finally the visual cortex where the information is converted into an image. Other important layers in the eye include the pigment epithelial layer, which is a pigmented single layer of cells that supports rods and cones through taking up waste material generated during the process of detecting light. Loss of function in any of these cells can result in diminished or lost sight. Retinal degeneration can occur early or late in life. ...