noun
definition
The transparent layer making up the outermost front part of the eye, covering the iris, pupil, and anterior chamber.
Examples of cornea in a Sentence
The eye is always a closed vesicle, and the internal cornea is extensive.
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.
Early names for it are Lac argenti and Luna cornea, the first referring to its form when freshly precipitated, the latter to its appearance after fusion.
In most cases this cornea is divided into lenticular facets corresponding to the underlying ommatidia.
Light is focused by the cornea and lens at the retina.
It is replaced by clear cornea removed in the same manner from the donor eye.
Potentially millions of people around the world could benefit from new research by a Lancaster University academic to develop an artificial cornea.
The recipient's immune system must overcome the factors involved in immune privilege to reject the donor cornea.
Pterygium is a growth that begins on the white of the eye that may or may not involve the cornea.
This scratching leads to scarring of the cornea, eventual blockage of the tear ducts, and blindness.
Astigmatism-An eye condition in which the cornea doesn't focus light properly on the retina, resulting in a blurred image.
Other symptoms include a decreased ability to sweat and changes in the cornea or outer layer of the eye.
A corneal abrasion occurs when there is a loss of cells from the epithelium or surface of the cornea.
The cornea is the clear curved structure found at the front of the eye.
It is very difficult to penetrate past the epithelium or top layer of the cornea.
The cornea is normally devoid of blood vessels yet has many sensory nerves.
But if a corneal abrasion is deep and penetrates the next layer of the cornea, then scarring is possible and complete healing of the abrasion may be delayed as long as three months.
When a missile type object causes an abrasion, the object can become embedded in the cornea or penetrate the eye.
If there is significant swelling of the cornea, then vision may be decreased.
Under blue cobalt light, the part of the cornea abraded will be stained by the dye and is easily seen by the examiner.
If any of the instilled dye leaks into the eye, then the cornea has been perforated and a small projectile may be inside the eye.
If the cornea has been perforated, then the patient is referred to a corneal specialist for surgery.
But patching is as of 2004 no longer done routinely because it decreases the amount of oxygen that gets to the cornea.
Also, the preservatives in these drops may irritate the cornea.
Approximately 10 to 25 percent of those with corneal abrasions will develop recurrent corneal erosion (RCE) a condition in which the epithelium of the cornea pulls off because it did not heal properly or completely.
This erosion is usually treated conservatively with lubricating drops and hypertonic saline ointment for a month or more, although some patient need a debridement of the cornea or laser treatment.
The HSV-1 virus can cause ocular herpes, a serious eye infection affecting the cornea (the clear window) of the eye, which can threaten vision and needs immediate medical attention and treatment.
The child may need antiviral drugs to keep the infection from scarring the cornea.
In addition to a deficiency in blood plasma of a protein known as ceruloplasmin, Wilson's disease is characterized by gold or greenish-gold discolorations of the cornea of the eye known as Kayser-Fleischer rings.
Other common problems include heart valve dysfunction, thickening of the heart muscle (cardiomyopathy), enlarged spleen and liver, clouding of the cornea, hearing loss, and carpal tunnel syndrome.
The major organs affected by MPS IV are the cornea and the cartilage, particularly the cartilage of the neck.
Contact lenses appear to be worn in direct contact with the cornea, but they actually float on a layer of tears that separates them from the cornea.
Over 32 million people in the United States wear these small lenses that fit on top of the cornea.
Rigid gas-permeable (RGP) daily-wear lenses are made of plastic that does not absorb water but allows oxygen to get from the atmosphere to the cornea.
Both infection and lenses that do not fit properly can damage the cornea.
On rare occasions, if a chalazion becomes quite big, it can press on the cornea.
If untreated or if treatment fails and is not corrected, conjunctivitis may cause visual impairment by spreading to other parts of the eye, such as the cornea.
The cornea located is a transparent tissue covering the eyeball and can be tested for intactness by lightly brushing a wisp of cotton directly on the outside of the eye.
When the eye is unable to produce tears or close completely or to blink, as often occurs in Bell's palsy, there is danger of doing permanent damage to the cornea of the eye.
Nail-patella syndrome has also been associated with abnormalities of the cornea, cataracts, and astigmatism.
More serious damage can be caused by hard or sharp objects that penetrate the surface of the eye and become embedded in the cornea or conjunctivae (the mucous membranes lining the inner surface of the eyelids).
It can also cause eye infections, in particular, of the conjunctiva and cornea.
In adults, less common effects of Lyme disease are heart abnormalities (such as irregular rhythm or cardiac block) and eye abnormalities (such as swelling of the cornea, tissue, or eye muscles and nerves).
The degree to which one is myopic depends on the powers of the cornea and the lens of the eye and the length of the eyeball.
Swelling of the cornea can occur if the eye does not have sufficient oxygen causing a transient increase in myopia.
For the child with diabetes, fluctuations in blood sugars can cause swelling of the cornea of the eye, leading to transient increases in myopia, which stabilize once the diabetes is controlled.
These lenses, called ortho-K lenses, flatten the cornea, changing the power of the cornea over time and decreasing myopia.
Steadily increasing amounts of copper circulating in the blood are deposited primarily in the brain, liver, kidneys, and the cornea of the eyes.
Another diagnostic procedure involves taking a corneal impression in which a swab or slide is pressed lightly against the cornea of the eye to determine whether viral material is present.
Keratoconus-An eye condition in which the central part of the cornea bulges outward, interfering with normal vision.