What is the Definition of Cornea?


If we want to discover the meaning of the term cornea, it is inevitable that, first of all, we know the etymological origin of the aforementioned word. In this case, we can state that it comes from the medieval Latin word “cornea”, which was a kind of tunic. A term that, in turn, is related to the Latin noun “cornus”, which means “horn”.

In the field of anatomy, the cornea is the name given to a membrane found in the anterior sector of the eyeball, through which the iris (the colored disc that, in its center, houses the pupil) can be seen. It is a transparent and hard element.

According to, the cornea is responsible for refracting light and gives the eye the ability to focus. It has a lens whose rear face is impregnated with aqueous humor (liquid that oxygenates and nourishes the different structures of the eyeball), while its front face is in contact with a tear film that provides protection.

In the same way, we cannot ignore that another of the most important functions of the cornea is to act as a protective shield for the eye. Yes, because it protects it from dust or germs of all kinds. Specifically, this is a task that it also shares with tears, the eye socket, the eyelids and what is known as the sclera.

Depending on the species, the cornea has more or fewer layers. While dogs and cats, for example, have a four-layer cornea, the human cornea has six layers: the corneal endothelium, Descemet’s membrane, Dua’s layer, corneal stroma, Bowman’s layer and the corneal epithelium.

From these parts we can learn interesting data such as these:
-The corneal endothelium is made up of what are hexagonal cells and is responsible for hydrating the cornea in order to keep it transparent.
-Descemet’s membrane, which sees its thickness increase every ten years. It is made up of collagen fibers.
-The layer of Dua, which is the last layer of the cornea.
-The corneal stroma, which is the thickest part.
-Bowman’s layer, which as the human being ages becomes finer.
-Corneal epithelium, which is formed by several layers of cells joined together.

Most of the oxygen needed by the cornea comes from the aqueous humor. However, the membrane also receives oxygen from the air in the atmosphere, tears and capillaries. As for nutrients, the cornea also receives them from the aqueous humor, tears and capillaries.

Among the diseases that can affect the cornea, astigmatism, glaucoma, corneal dystrophy, megalocornea and keratitis appear. Depending on the type of disorder, treatment may require the use of contact lenses or refractive surgery.

Likewise, another series of problems, conditions or diseases that can affect the cornea are corneal erosions, ulcers, corneal opacity, allergies…