American Heritage® Dictionary of the English Language, Fourth Edition
- n. A delicate, multilayered, light-sensitive membrane lining the inner eyeball and connected by the optic nerve to the brain.
Century Dictionary and Cyclopedia
- n. The innermost and chiefly nervous coat of the posterior part of the eyeball, between the choroid coat and the vitreous humor. It extends from the entrance into the eyeball of the optic nerve toward the crystalline lens, terminating in the ora serrata. A modified division of the retinal structure is, however, continued forward as the pars ciliaris retinæ. The retina consists of a delicate and complex expansion and modification of the optic nerve, supported by a network of connective tissue. It may be divided into ten layers: internally, next the hyaloid membrane of the vitreous humor, the internal limiting membrane, formed of the expanded bases of the fibers of Muller; the fibers of the optic nerve; layer of ganglion-cells; internal molecular or granular layer; inner nuclear layer: external molecular or granular layer: external nuclear layer; external limiting membrane, which is connected with the ends of Muller's fibers; layer of rods and cones, or bacillary layer; (10) pigmentary layer. In the center of the back part of the retina, near the line of the optic axis, is the macula lutea, the most sensitive part of the retina; and in the center of the macula is a depression, the fovea centralis, in which the rods are absent. The color of the macula is due to a yellow pigment. About one tenth of an inch internally to the fovea is the point of entrance of the optic nerve with its central artery; the retina is incomplete at this point, and constitutes the “blind spot.” The nerve-fibers have been estimated to number 400,000 broad and as many narrow fibers, and for each fiber there are 7 cones, 100 rods, and 7 pigment-cells. The retina serves the purpose of vision in being the organ through or by means of which vibrations of luminiferous ether excite the optic nerve to its appropriate activity. See
- n. anatomy The thin layer of cells at the back of the eyeball where light is converted into neural signals sent to the brain.
GNU Webster's 1913
- n. (Anat.) 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.
- n. the innermost light-sensitive membrane covering the back wall of the eyeball; it is continuous with the optic nerve
- From Medieval Latin retina, the diminutive form of Latin rete ("net"), probably from the Vulgar Latin phrase (tunica) *retina, literally "net-like tunic", used to describe the blood vessel system at the back of the eye. (Gerard of Cremona may have created this phrase as a translation for Arabic (tabaqa) sabakiva "net-like layer", which translates Ancient Greek ἀμφιβληστροειδής (χιτών)). (Wiktionary)
- Middle English, from Medieval Latin rētina, from Latin rēte, net. (American Heritage® Dictionary of the English Language, Fourth Edition)
“The clarity of the images produced on the retina is a factor which determines the power of vision.”
“The retina is a thin layer of nerve tissue that coats the back of the eye and enables the eye to see.”
“Inverted retina" is part of visual system that works very well in humans and birds, so on what basis does Johnson call this "bad design".”
“Using an intact retina from a guinea pig, the researchers recorded spikes of electrical impulses from ganglion cells and calculated the human retina can transmit data at roughly 10 million bits per second.”
“Our eyes (retina is behind the optic nerve, not intelligently in front of it like exists in other life forms), the bones are an engineering disaster, the appendix has no function, the coccyx is a tail bone (we have no tail), and we possess pseudo genes (genes that exist but do not function).”
“I would argue that the design for the retina is in fact the best choice, given the restraints of its design and past evolutionary choices/routes.”
“Hubel and Wiesel were also able to show by their experiments that the ability of the cells in the visual cortex to interpret the code of the impulse message from the retina is developed directly after birth.”
“The pupil, or aperture, through which rays pass to the retina, is the tenderest part of the eye; the member which we most sedulously guard from hurt as being the dearest of our members; the one which feels most acutely the slightest injury, and the loss of which is irreparable.”
“I had already been receiving laser treatments for diabetic retinopathy for a couple of years, so I called my retina specialist later that morning, then lived through an agonizing 24 hours until I could see him the following day.”
“In a preliminary study, Australian researchers examined the photographs of the light-sensitive part of the eye called the retina in 13 people with Alzheimer's, 13 with mild cognitive impairment and 110 healthy individuals.”
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Words that describe the art of the impressionist era.
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A collection of anatomical names for parts of humans, animals, plants, and whatever anyone else can recall.
words that are not my most cherished words, but are still appealing and useful to me.
parts of the human eye
tomorrow I am getting new glasses because my other ones were run over by a car
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