Cornea

cornealcorneal diseasecorneal diseasescorneal membranecorneal problems corneal tissuecornea.corneal apexcorneal burncorneal deposits
The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber.wikipedia
782 Related Articles

Human eye

eyeeyeseyeball
The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber.
The outermost layer, known as the fibrous tunic, is composed of the cornea and sclera.

Pupil

pupilspupillaryanatomical pupil
The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber.
The image of the pupil as seen from outside the eye is the entrance pupil, which does not exactly correspond to the location and size of the physical pupil because it is magnified by the cornea.

Anterior chamber of eyeball

anterior chamberanterior chamber of the eyeanterior
The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber.
The anterior chamber (AC) is the aqueous humor-filled space inside the eye between the iris and the cornea's innermost surface, the endothelium.

LASIK

laser eye surgerylasik surgerylaser-assisted in situ keratomileusis
The cornea can be reshaped by surgical procedures such as LASIK.
The LASIK surgery is performed by an ophthalmologist who uses a laser or microkeratome to reshape the eye's cornea in order to improve visual acuity.

Iris (anatomy)

irisirisesirides
The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber.
A person's "eye color" is actually the color of one's iris, the cornea being transparent and the white sclera entirely outside the area of interest.

Corneal limbus

limbuscorneoscleral limbusLimbal
The human cornea borders with the sclera via the corneal limbus.
The corneal limbus is the border of the cornea and the sclera (the white of the eye).

Corneal epithelium

outer corneal layercorneal epithelialCorneal epithelial cells
1) Corneal epithelium: an exceedingly thin multicellular epithelial tissue layer (non-keratinized stratified squamous epithelium) of fast-growing and easily regenerated cells, kept moist with tears. Irregularity or edema of the corneal epithelium disrupts the smoothness of the air/tear-film interface, the most significant component of the total refractive power of the eye, thereby reducing visual acuity. It is continuous with the conjunctival epithelium, and is composed of about 6 layers of cells which are shed constantly on the exposed layer and are regenerated by multiplication in the basal layer.
The corneal epithelium (epithelium corneæ anterior layer) is made up of epithelial tissue and covers the front of the cornea.

Dua's layer

The human cornea has five layers (possibly six, if the Dua's layer is included).
Dua's layer, according to a 2013 paper by Harminder Singh Dua's group at the University of Nottingham, is a layer of the cornea that had not been detected previously.

Dioptre

diopterdioptersD
In humans, the refractive power of the cornea is approximately 43 dioptres.
The cornea accounts for approximately two-thirds of this refractive power (about 40 dioptres) and the crystalline lens contributes the remaining one-third (about 20 dioptres).

Sclera

sclerotizedsclerotisedwhites of the eyes
The human cornea borders with the sclera via the corneal limbus.
It is continuous with the dura mater and the cornea, and maintains the shape of the globe, offering resistance to internal and external forces, and provides an attachment for the extraocular muscle insertions.

Collagen

procollagencollagenscollagen fibers
2) Bowman's layer (also known as the anterior limiting membrane): when discussed in lieu of a subepithelial basement membrane, Bowman's Layer is a tough layer composed of collagen (mainly type I collagen fibrils), laminin, nidogen, perlecan and other HSPGs that protects the corneal stroma. When discussed as a separate entity from the subepithelial basement membrane, Bowman's Layer can be described as an acellular, condensed region of the apical stroma, composed primarily of randomly organized yet tightly woven collagen fibrils. These fibrils interact with and attach onto each other. This layer is eight to 14 micrometres (μm) thick and is absent or very thin in non-primates.
It is also abundant in corneas, blood vessels, the gut, intervertebral discs, and the dentin in teeth.

Stroma of cornea

corneal stromastromasubstantia propria
3) Corneal stroma (also substantia propria): a thick, transparent middle layer, consisting of regularly arranged collagen fibers along with sparsely distributed interconnected keratocytes, which are the cells for general repair and maintenance. They are parallel and are superimposed like book pages. The corneal stroma consists of approximately 200 layers of mainly type I collagen fibrils. Each layer is 1.5-2.5 μm. Up to 90% of the corneal thickness is composed of stroma. There are 2 theories of how transparency in the cornea comes about:
The substantia propria (or stroma of cornea) is fibrous, tough, unyielding, and perfectly transparent.

Bowman's membrane

Anterior elastic laminabowman membraneBowman's layer
2) Bowman's layer (also known as the anterior limiting membrane): when discussed in lieu of a subepithelial basement membrane, Bowman's Layer is a tough layer composed of collagen (mainly type I collagen fibrils), laminin, nidogen, perlecan and other HSPGs that protects the corneal stroma. When discussed as a separate entity from the subepithelial basement membrane, Bowman's Layer can be described as an acellular, condensed region of the apical stroma, composed primarily of randomly organized yet tightly woven collagen fibrils. These fibrils interact with and attach onto each other. This layer is eight to 14 micrometres (μm) thick and is absent or very thin in non-primates.
The Bowman's membrane (Bowman's layer, anterior limiting lamina, anterior elastic lamina) is a smooth, acellular, nonregenerating layer, located between the superficial epithelium and the stroma in the cornea of the eye.

Aqueous humour

aqueous humoraqueous fluidocular
Similarly, nutrients are transported via diffusion from the tear fluid through the outside surface and the aqueous humour through the inside surface, and also from neurotrophins supplied by nerve fibres that innervate it. In humans, the cornea has a diameter of about 11.5 mm and a thickness of 0.5–0.6 mm in the center and 0.6–0.8 mm at the periphery.
Provides nutrition (e.g. amino acids and glucose) for the avascular ocular tissues; posterior cornea, trabecular meshwork, lens, and anterior vitreous.

Corneal keratocyte

keratocytescorneal fibroblastsCorneal corpuscle
3) Corneal stroma (also substantia propria): a thick, transparent middle layer, consisting of regularly arranged collagen fibers along with sparsely distributed interconnected keratocytes, which are the cells for general repair and maintenance. They are parallel and are superimposed like book pages. The corneal stroma consists of approximately 200 layers of mainly type I collagen fibrils. Each layer is 1.5-2.5 μm. Up to 90% of the corneal thickness is composed of stroma. There are 2 theories of how transparency in the cornea comes about:
This corneal layer, representing about 85-90% of corneal thickness, is built up from highly regular collagenous lamellae and extracellular matrix components.

Corneal endothelium

endotheliumcorneal endothelial cellendothelial layer
7) Corneal endothelium: a simple squamous or low cuboidal monolayer, approx 5 μm thick, of mitochondria-rich cells. These cells are responsible for regulating fluid and solute transport between the aqueous and corneal stromal compartments. (The term endothelium is a misnomer here. The corneal endothelium is bathed by aqueous humor, not by blood or lymph, and has a very different origin, function, and appearance from vascular endothelia.) Unlike the corneal epithelium, the cells of the endothelium do not regenerate. Instead, they stretch to compensate for dead cells which reduces the overall cell density of the endothelium, which affects fluid regulation. If the endothelium can no longer maintain a proper fluid balance, stromal swelling due to excess fluids and subsequent loss of transparency will occur and this may cause corneal edema and interference with the transparency of the cornea and thus impairing the image formed. Iris pigment cells deposited on the corneal endothelium can sometimes be washed into a distinct vertical pattern by the aqueous currents - this is known as Krukenberg's Spindle.
The corneal endothelium is a single layer of cells on the inner surface of the cornea.

Tears

lacrimationteartear film
1) Corneal epithelium: an exceedingly thin multicellular epithelial tissue layer (non-keratinized stratified squamous epithelium) of fast-growing and easily regenerated cells, kept moist with tears. Irregularity or edema of the corneal epithelium disrupts the smoothness of the air/tear-film interface, the most significant component of the total refractive power of the eye, thereby reducing visual acuity. It is continuous with the conjunctival epithelium, and is composed of about 6 layers of cells which are shed constantly on the exposed layer and are regenerated by multiplication in the basal layer.

Krukenberg's spindle

7) Corneal endothelium: a simple squamous or low cuboidal monolayer, approx 5 μm thick, of mitochondria-rich cells. These cells are responsible for regulating fluid and solute transport between the aqueous and corneal stromal compartments. (The term endothelium is a misnomer here. The corneal endothelium is bathed by aqueous humor, not by blood or lymph, and has a very different origin, function, and appearance from vascular endothelia.) Unlike the corneal epithelium, the cells of the endothelium do not regenerate. Instead, they stretch to compensate for dead cells which reduces the overall cell density of the endothelium, which affects fluid regulation. If the endothelium can no longer maintain a proper fluid balance, stromal swelling due to excess fluids and subsequent loss of transparency will occur and this may cause corneal edema and interference with the transparency of the cornea and thus impairing the image formed. Iris pigment cells deposited on the corneal endothelium can sometimes be washed into a distinct vertical pattern by the aqueous currents - this is known as Krukenberg's Spindle.
Krukenberg's spindle is the name given to the pattern formed on the inner surface of the cornea by pigmented iris cells that are shed during the mechanical rubbing of posterior pigment layer of the iris with the zonular fibrils that are deposited as a result of the currents of the aqueous humor.

Descemet's membrane

descemet membranemembrane of DescemetPosterior elastic lamina
6) Descemet's membrane (also posterior limiting membrane): a thin acellular layer that serves as the modified basement membrane of the corneal endothelium, from which the cells are derived. This layer is composed mainly of collagen type IV fibrils, less rigid than collagen type I fibrils, and is around 5-20 μm thick, depending on the subject's age. Just anterior to Descemet's membrane, a very thin and strong layer, Dua's layer, 15 microns thick and able to withstand 1.5 to 2 bars of pressure.
Descemet's membrane (or the Descemet membrane) is the basement membrane that lies between the corneal proper substance, also called stroma, and the endothelial layer of the cornea.

Corneal abrasion

Corneal ulcercorneal abrasionscorneal damage
Corneal abrasion - a medical condition involving the loss of the surface epithelial layer of the eye's cornea as a result of trauma to the surface of the eye.
Corneal abrasion is a scratch to the surface of the cornea of the eye.

Corneal dystrophy

corneal dystrophiesdystrophycone rod dystrophy
Corneal dystrophy - a condition in which one or more parts of the cornea lose their normal clarity due to a buildup of cloudy material.
Corneal dystrophy is a group of rare hereditary disorders characterised by bilateral abnormal deposition of substances in the transparent front part of the eye called the cornea.

Corneal ulcer

corneal ulcerationulcerationUlcerative Keratitis
Corneal ulcer - an inflammatory or infective condition of the cornea involving disruption of its epithelial layer with involvement of the corneal stroma.
Corneal ulcer is an inflammatory or more seriously, infective condition of the cornea involving disruption of its epithelial layer with involvement of the corneal stroma.

Keratoconus

Corneal ectasiaectasiaStriae of Vogt
Keratoconus - a degenerative disease, the cornea thins and changes shape to be more like a cone.
Keratoconus (KC) is a disorder of the eye which results in progressive thinning of the cornea.

Keratitis

bacterial keratitisCorneal infectioninflammation of the cornea
Keratitis - inflammation of the cornea.
Keratitis is a condition in which the eye's cornea, the clear dome on the front surface of the eye, becomes inflamed.

Corneal transplantation

corneal transplantkeratoplastycornea transplant
If the corneal stroma develops visually significant opacity, irregularity, or edema, a cornea of a deceased donor can be transplanted.
Corneal transplantation, also known as corneal grafting, is a surgical procedure where a damaged or diseased cornea is replaced by donated corneal tissue (the graft).