Retina

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ret·i·na / ˈretn-ə/ • n. (pl. ret·i·nas or ret·i·nae / ˈretnˌē; ˈretnˌī/ ) a layer at the back of the eyeball containing cells that are sensitive to light and that trigger nerve impulses that pass via the optic nerve to the brain, where a visual image is formed. DERIVATIVES: ret·i·nal / ˈretn-əl/ adj.

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retina The light-sensitive membrane that lines the interior of the eye. The retina consists of two layers. The outer layer (pigment epithelium) is pigmented, which prevents the back reflection of light and consequent decrease in visual acuity. The inner layer contains nerve cells, blood vessels, and two types of light-sensitive cells (rods and cones). Light passing through the lens stimulates individual rods and cones, which generates nerve impulses that are transmitted through bipolar and ganglion cells to the optic nerve, and hence to the brain, where the visual image is formed. Information can also be transferred horizontally within the retina via a network of horizontal and amacrine cells (see illustration).

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retina Inner layer of the eye, composed mainly of different kinds of neurons, some of which are the visual receptors of the eye. Receptor cells (cones and rods) are sensitive to light. Cones respond to the spectrum of visible colours; rods respond to shades of grey and to movement. The rods and cones connect with sensory neurons, which in turn connect with the optic nerve, which carries the visual stimuli to the brain.

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retina The light-sensitive membrane in the eye on to which incoming light is focused. The retina has two layers; the outer layer is pigmented and so prevents the back-reflection of light; the inner layer contains blood vessels, nerve endings, and light-sensitive cells (rods and cones). See also TAPETUM.

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retina (ret-in-ă) n. the light-sensitive layer that lines the interior of the eye. The inner part of the retina, next to the cavity of the eyeball, contains rods and cones (light-sensitive cells) and their associated nerve fibres. The outer part (retinal pigment epithelium, RPE) is pigmented to prevent the passage of light.
retinal (ret-in-ăl) adj.

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retina: see vision; eye.

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retina XIV. — medL., perh. f. L. rēte net.