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Retina |
Also found in: Dictionary/thesaurus, Encyclopedia, Wikipedia, Hutchinson | 0.11 sec. |
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retina /ret·i·na/ (ret´i-nah) [L.] the innermost tunic of the eyeball, containing the neural elements for reception and transmission of visual stimuli.
Retina Light sensitive layer of the eye, that consists of four major layers: the outer neural layer, containing nerve cells and blood vessels, the photoreceptor layer, a single layer that contains the light sensing rods and cones, the pigmented retinal epithelium (PRE) and the choroid, consisting of connective tissue and capillaries. Mentioned in: Cataract Surgery, Cataracts, Color Blindness, Eye and Orbit Ultrasounds, Eye Examination, Eye Glasses and Contact Lenses, Eye Muscle Surgery, Glaucoma, Hyperopia, Macular Degeneration, Microphthalmia and Anophthalmia, Myopia, Photorefractive Keratectomy and Laser-Assisted In-Situ Keratomileusis, Radial Keratotomy, Retinal Artery Occlusion, Retinal Vein Occlusion, Retinoblastoma, Uveitis, Vitiligo retina (ret´ n a 10-layered, delicate nervous-tissue membrane of the eye, continuous with the optic nerve, that receives images of external objects and transmits visual impulses through the optic nerve to the brain. retina the innermost of the three tunics of the eyeball, surrounding the vitreous body and continuous posteriorly with the optic nerve. The retina is composed of two parts: an optical part in the fundus of the eye that is sensitive to light, and a nonsensitive pigmented part that lines the ciliary body and iris. The light-sensitive neurons are arranged in three layers; the first layer is made up of rods and cones and the other two transmit impulses from the rods and cones to the optic nerve The rods are sensitive to dim light of a variety of wavelengths, and the cones are sensitive to bright light of more restricted wavelengths and are responsible for color vision. Visual acuity is greatest in the central part of the retina. See also eye. silent retina syndrome see sudden acquired retinal degeneration. |
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