Cones (retina) | definition of Cones (retina) by Medical dictionary
cone cell (redirected from Cones (retina))
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cone cell (kōn sel)
One of the two types of visual receptor cells of the retina, essential for visual acuity and color vision; the second type is the rod cell.
A cell in the retina whose scleral end forms a cone that serves as a light receptor. Vision in bright light, color vision, and acute vision depend on the function of the cones. See: rod cell
cone cell a cone-shaped cell sensitive to light, found throughout the retina of most vertebrate eyes but concentrated within the FOVEA (see RETINAL CONVERVENCE). Cones are concerned with discrimination of colour and with visual acuity. There are three types of cone cell, each containing a different IODOPSIN and each giving maximum response when stimulated by the blue (450 nm), green (525 nm), and red (550 nm) parts of the visible spectrum. Our perception of any given colour is produced by the relative degree to which each cone is stimulated by any given wavelength of visible light. This is in accord with the TRICHROMATIC THEORY of colour vision which suggests that all colours can be produced by the mixing of blue, green and red. Thus the brain detects a yellow light by the equal stimulation of red and green cone gells. A pigment defect in one or more of the types of cone cell can lead to COLOUR BLINDNESS.