Retina Sentence Examples
In hypermetropia the retina is in front of the principal focus of the eye.
One result of this among the Vertebrata is that the eyeball is pink in colour, since the cornea, iris and retina being transparent, the red blood contained in the capillaries is unmasked by the absence of pigmentary material.
In the retina the cones prevail in numbers over the rods, as in the mammals, and their tips contain, as in other Sauropsida, coloured drops of oil, mostly red or yellow.
All objects, therefore, which lie beyond a certain point (the conjugate focus of the dioptric system of the eye, the far point) are indistinctly seen; rays from them have not the necessary divergence to be focused in the retina, but may obtain it by the interposition of suitable concave lenses.
Thus light, pressure, or mechanical stimulation acting on the retina and optic nerve invariably produces luminous impressions.Advertisement
The angle under which the object appears depends upon the distance and size of the object, or, in other words, the size of the image on the retina is determined by the distance and the dimensions of the object.
A large pupil and highly curved cornea admit plenty of light to keep the image on the retina bright.
They are at the same time both optic nerve-end cells, that is to say, retina cells, and corneagen cells or secretors of the chitinous lens-like cornea.
Further, he extended the work of Maurolycus, and demonstrated the exact analogy between the eye and the camera and the arrangement by which an inverted image is produced on the retina.
It is the result of the too great intensity of the light incident upon the retina, and which in normal eyeballs is adequately diminished by the absorptive power of the pigmentary material.Advertisement
In regard to sense-organs, ophthalmoscopic observations on the eyes of living mammals (other than man) have revealed the existence of great variation in the arrangement of the bloodvessels, as well as in the colour of the retina; blue and violet seem to be unknown, while red, yellow and green form the predominating shades.
The other portions which are reproduced on the retina on the regions surrounding the yellow spot will also be perceived, but with reduced definition.
This is effected by the power of accommodation of the eye, which can so alter the focal length of its crystalline lens that images of objects at different distances can be produced rapidly and distinctly one after another upon the retina.
On the other hand, as the observer recedes from the object, the apparent size, and also the image on the retina diminishes; details become more and more confused, and gradually, after a while, disappear altogether, and ultimately the external configuration of the object as a whole is no longer recognizable.
This case arises when the visual angle, under which the object appears, is approximately a minute of arc; it is due to the physiological construction of the retina, for the ends of nerve fibres, which receive the impression of light, have themselves a definite size.Advertisement
The retina is more enriched with DHA than any other tissue in the human body as it naturally accumulates here.
If the plaques become bigger they can cut off part or all of the blood going to or from the retina.
Light is focused by the cornea and lens at the retina.
Sen. Dianne Feinstein, D-Calif., is especially enamored of the picture, retina scan and fingerprints modems.
The Biometric devices scan the fingerprint or retina of the eye to allow only authorized personnel to gain access to secure areas.Advertisement
More serious problems include abnormalities of the vitreous gel, degeneration of the retina and glaucoma.
I also have macula hypoplasia (underdeveloped retina) which causes my low vision.
It has also been suggested that supplements containing lutein may also protect the retina.
Taking lutein supplements can significantly increase blood levels of lutein supplements can significantly increase blood levels of lutein & the amount of macular pigment present in the retina.
It affects the macula in the center of the retina.Advertisement
Near the center of the back of the retina is an area called the macula, which is the point of sharpest vision.
Individuals with wet macular degeneration may see a dark spot or spots within their central vision due to the blood leakage under the retina.
In domesticated mammals the retina is the reflective area at the back of the eye which responds to light.
If all these cutaneous manifestations are present, then hamartomas maybe present within the CNS, kidney, retina and lungs etc.
The joined up path that signals travel down from retina to optic nerve then optic chiasm then occipital lobe is called the visual pathway.
Looking at the retina Your doctor will often look at the retina with a device called an ophthalmoscope.
The laser isn't used on the blood vessels directly, but is scattered over the whole retina (pan retinal photocoagulation ).
Light rays from a distant object are almost parallel so do not need much refraction to focus onto the retina.
He has a detached retina, which cannot be fixed.
The iris controls the amount of light that actually reaches the retina.
Once there, they protect the retina from damage caused by sunlight.
Their research aims to discover why diabetes damages the retina, the complex light-sensitive tissue at the back of the eye.
The retina of the octopus is constructed more logically than the mammalian retina.
Views out to the peripheral retina may be obtained with some lenses.
The role of the retinal pigment epithelium in regulating development of the neural retina.
February 1981 Has an eye operation in BogotÃ¡, Colombia, to repair a damaged retina.
He's created an artificial retina that copies the function of a real one down to the firing of individual neurons.
Proliferative retinopathy At this stage, some of the tiny blood vessels in the retina become blocked.
Both retina and iris scans are currently being used in government and corporate security systems around the world.
The real-time image allows you to view the retina and anterior segment with ease using the 20 second video capture feature.
The retina at the back of the eye requires a constant blood supply.
The visual system comprises the retina, the visual pathway, and visual cortex.
Preserves are used to conceal deformities or to protect the eyes in the many conditions where they cannot tolerate bright light, such as ulceration and inflammation of the cornea, certain diseases of the iris, ciliary body, choroid, and retina.
He 's created an artificial retina that copies the function of a real one down to the firing of individual neurons.
Force cooperate him to use the retina eye scanner, which will open the door.
No scope for anonymity and personal freedom - ID cards, CCTV, databases, DNA samples, retina scans?
Retina Dance moved in - great to have them with us.
The rats, which had been given both human and rat retina cells, retained the cells and did n't go blind.
This is the first image processing after the signal leaves the retina in the eye.
The extra converging power of a spectacle lens permits the eye to focus the image on the retina.
Horses ' eyes contain an additional shiny layer behind the retina called the tapetum lucidum, a feature shared by nocturnal animals.
Does anyone on here suffer from either temporal arteritis or vitreous detachment with torn retina?
Urodele amphibians such as the newt can regenerate their limbs, jaws, lens, retina and large sections of the heart.
They are also in the wrong place - growing on the surface of the retina and into the vitreous gel.
The tumor mass is growing from the retina (arrow) into the vitreous cavity.
When exposed to light, the retina sends a message through the nerve pathway to the brain to let you know it is time to wake up.
Over time, this can cause cataracts and retina damage that is not easily reversed.
Absorption of the rays by the central retina (called the macula) in the back of the eye causes degeneration of this tissue, which results in decreased central vision or fine pinpoint vision.
Even worse is the permanent retina scarring and cataracts that result from ultraviolet damage.
Keep in mind that if you're suffering from a severe case of floaters, or a sudden burst of floaters or flashes of light, you could be suffering from a much more serious eye condition such as a detached retina.
Photos taken with the iPhone 4 are much crisper than other smartphones because of the retina display.
It does have the upgraded camera, retina display, and FaceTime video chat function though.
During the first three to six months, the retina is fairly well-developed, and babies can visualize small objects.
Parts of the retina do not develop correctly if melanin pigment is not present during development.
They may have reduced depth perception due to altered nerve connections from the retina to the brain.
If people with albinism seem to have reddish eyes, it is because light is being reflected from the back of the eye (retina) in much the same way as happens when people are photographed with an electronic flash.
Astigmatism-An eye condition in which the cornea doesn't focus light properly on the retina, resulting in a blurred image.
Symptoms develop within the first few months of life and include poor appetite, failure to grow, enlarged liver and spleen, and the appearance of cherry red spots in the retina of the eye.
The uvea lies between the retina and sclera.
Diabetic retinopathy-A condition seen most frequently in individuals with poorly controlled diabetes mellitus where the tiny blood vessels to the retina, the tissues that sense light at the back of the eye, are damaged.
White areas in the retina, called phakomas, are characteristic of the disease (and may aid in diagnosis) but do not result in visual disturbances.
Examination of the eyes of a child with Tay-Sachs disease reveals a characteristic cherry-red spot at the back of the eye in an area called the retina.
Lenses work by changing the direction of light so that images come into focus on the retina.
Lens-The transparent, elastic, curved structure behind the iris (colored part of the eye) that helps focus light on the retina.
The retina transforms the image it receives into electrical signals that are sent to the brain via the optic nerve.
Hypertension can cause damage to blood vessels in the eyes, leading to retinopathy, or damage to the retina.
Retinoblastoma is a malignant tumor of the retina that occurs predominantly in young children.
The eye has three layers, the sclera, the choroid, and the retina.
The lens then focuses the light onto the retina, the innermost of the three layers.
The job of the retina is to transform the light into information that can be transmitted to the optic nerve, which will transmit this information to the brain.
Occasionally a tumor, called a retinoblastoma, develops in the retina of the eye.
A malignant tumor of the retina (retinoblastoma) can result when just one retinal cell loses control of it cell cycle and replicates out of control.
During the examination, a cotton swab or a metal instrument with a flattened tip is used to press on the outer lens of the eye so that a better view of the front areas of the retina can be obtained.
An intraocular retinoblastoma may only involve the retina or could involve other parts of the eye.
Long-term side effects of radiation treatment can include cataracts, vision problems, bleeding from the retina, and decreased growth of the bones on the side of the head.
Cryotherapy is a treatment often used in conjunction with radiation therapy but can also be used alone on small tumors located on the front part of the retina.
The long-term side effects of this treatment can include cataracts and damage to the retina, which can lead to impaired vision.
Intraocular retinoblastoma-Cancer of the retina that is limited to the eye and has not spread to other parts of the body.
Optic nerve-A bundle of nerve fibers that carries visual messages from the retina in the form of electrical signals to the brain.
Incomplete development of any structures in the eye (coloboma) or failure of the retina to develop properly (retinal dysplasia) produces vision problems.
Retinal hemorrhage-Bleeding of the retina, a key structure in vision located at the back of the eye.
These illnesses include pneumonia and inflammations of the liver (hepatitis), brain (encephalitis), esophagus (esophagitis), large intestine (colitis), and retina of the eye (retinitis).
About 10 percent of these babies will be born with obvious problems, including prematurity, lung problems, an enlarged liver and spleen, jaundice, anemia, low birth weight, small head size, and inflammation of the retina.
It is important to guard against too much oxygen, as this may damage the retina and cause loss of vision.
In a normal eye the incoming visual images meet on the retina in the back of the eye.
If these visual images converge in front of the retina instead of on the retina, then one is myopic.
Individuals with high myopia, greater than six diopters, can develop pathological changes in the retina, called degenerative myopia.
Normal color vision requires the use of specialized receptor cells called cones, which are located in the retina of the eye.
Achromatopsia, the complete inability to distinguish color, is an autosomal recessive disease of the retina.
Accidents or strokes that damage the retina or affect particular areas of the brain eye can lead to color blindness.
Cones-Receptor cells, located in the retina of the eye, that allow the perception of colors.
Rods-Photoreceptors, located in the retina of the eye, that are highly sensitive to low levels of light.
It can cause damage to the retina of the eye, vision loss, or blindness.
Specifically, vitamin A helps your body form the chemicals necessary to perceive light and color in your retina.
The human retina needs vitamin A in order to function.
Warnings against this variation of eye tattooing include risk of eye-tissue penetration which can potentially damage the tissue and retina impairing overall eye functionality.
Effectively an iPhone without the phone, an iPod touch features a very large 4-inch Retina touchscreen display and it is powered by the same iOS platform as the popular iPhone.
These, falling in turn on the lens of the human eye, are converged by it and form an image on the retina.
First of all, the distinction of white and black, with their mean point in grey, is referred to the activity or inactivity of the total retina in the graduated presence or absence of full light.
Within the field of vision, all people have a blind spot on the retina of the eye which cannot receive visual images.
Lutein is the primary carotenoid located in the center of the retina, called the macula.
The pupil allows the light to enter the eye to stimulate the retina.
While the HTC Droid X and Droid X both have large 4.3-inch displays, the Apple iPhone 4 has a better pixel density on its "retina" display (326 pixels per inch vs. 217 pixels per inch).
Also nerve connections between the retina and brain are altered if melanin is not present in the retina during development.
For people who are farsighted, images come into focus behind the retina; for people who are nearsighted, images come into focus in front of the retina.
A normal cell of the retina goes through a growth cycle during which it produces new cells.
The opthalmoscope shines a bright light into the eye, which helps the doctor to visualize the retina.
Near the posterior pole of the fundus, but somewhat excentrically placed towards the temporal or outer side, is the fovea centralis, a slight depression in the retina, composed almost entirely of cones, the spot of most acute vision.
He argued that the different humours of the human eye so refract rays of light as to produce an image on the retina which is free from colour, and he reasonably argued that it might be possible to produce a like result by combining lenses composed of different refracting media.'
These external and less sensitive parts of the retina, therefore, merely give information as to the general arrangement of the objects and to a certain extent act as guide-post in order to show quickly and conveniently, although not distinctly, the places in the image which should claim special attention.
Only points lying on the plane focused for can be sharply reproduced in the retina, which acts as object-plane to the retina.
Moreover, with such exceptionally narrow pencils shadows are formed on the retina of the observer's eye, from the irregularities in the eye itself.
Curiously enough, however, they differ from the cephalic Molluscan eye in the fact that, as in the vertebrate eye, the filaments of the optic nerve penetrate the retina, and are connected with the re surfaces of the nerve-end cells nearer the lens instead of with the opposite end.
He seems to have been well acquainted with the projection of images of objects through small apertures, and to have been the first to show that the arrival of the image of an object at the concave surface of the common nerve - or the retina - corresponds with the passage of light from an object through an aperture in a darkened place, from which it falls upon a surface facing the aperture.
The kaleidophone, intended to present visibly the movements of a sonorous body, consisted of a vibrating wire or rod carrying a silvered bead reflecting a point of light, the motions of which, by persistence of the successive images on the retina, were thus represented in curves of light.
M`Kendrick, of Glasgow, he investigated the physiological action of light, and examined the changes which take place in the electrical condition of the retina under its influence.
This theory of complementary colours as due to the polarity in the qualitative action of the retina is followed by some criticism of Newton and the seven colours, by an attempt to explain some facts noted by Goethe, and by some reference to the external stimuli which cause colour.
When, for instance, the axons of the ganglion cells of the retina are severed by section of the optic nerve, and thus their influence upon the nerve cells of the visual cerebral centres is set aside, the nerve cells of those centres undergo secondary atrophy (Gadden's atrophy).
All colours are complementary, or go in pairs; each pair makes up the whole activity of the retina, and so is equivalent to white; and the two partial activities are so connected that when the first is exhausted the other spontaneously succeeds.
In this case the eye is always directed so that the part of the image which is wished to be viewed exactly falls upon the most sensitive portion of the retina, viz.
Atropine is universally and constantly used in ophthalmic practice in order to dilate the pupil for examination of the retina by the ophthalmoscope, or in cases where the inflamed iris threatens to form adhesions to neighbouring parts.
The simplest is for the impression made by an observed object on the retina, the eye; in this connexion the term "after-image" (better "after-sensation") is used for an image which remains when the eye is withdrawn from a brilliantly lighted object; it is called positive when the colour remains the same, negative when the complementary colours are seen.