noun
definition
The thin layer of cells at the back of the eyeball where light is converted into neural signals sent to the brain.
Examples of retina in a Sentence
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.
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.
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.
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.
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.
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.
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.
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 Bogotá, 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.