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Definition of Retina
1. Noun. The innermost light-sensitive membrane covering the back wall of the eyeball; it is continuous with the optic nerve.
Group relationships: Eye, Oculus, Optic
Generic synonyms: Membrane, Tissue Layer
Derivative terms: Retinal
Definition of Retina
1. n. The delicate membrane by which the back part of the globe of the eye is lined, and in which the fibers of the optic nerve terminate. See Eye.
Definition of Retina
1. Noun. (anatomy) The thin layer of cells at the back of the eyeball where light is converted into neural signals sent to the brain. ¹
¹ Source: wiktionary.com
Definition of Retina
1. a membrane of the eye [n -NAS or -NAE]
Medical Definition of Retina
1. Light sensitive layer of the eye. In vertebrates, looking from outside, there are four major cell layers: (i) the outer neural retina, which contains neurons (ganglion cells, amacrine cells, bipolar cells) as well as blood vessels, (ii) the photoreceptor layer, a single layer of rods and cones, (iii) the pigmented retinal epithelium (PRE or RPE), (iv) the choroid, composed of connective tissue, fibroblasts and including a well vascularised layer, the chorio capillaris, underlying the basal lamina of the PRE. Behind the choroid is the sclera, a thick organ capsule. In molluscs (especially cephalopods such as the squid) the retina has the light sensitive cells as the outer layer with the neural and supporting tissues below. See: retinal rods, retinal cones, rhodopsin. This entry appears with permission from the Dictionary of Cell and Molecular Biology (11 Mar 2008)