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The outermost layer of the eye is called Cornea. It is one of the essential components of the human eye as it allows the light to enter into the eye for us to have the vision. A cornea is generally 12mm in length and 11mm in height. The cornea also contributes around 70 percent of the focusing power of the eye. That is the main reason why it is imperative to take care of the corneas.
Refractive problems like myopia, hyperopia, and astigmatism are caused due to a change in the shape of the cornea.
Structure of the Cornea
There are five layers of the cornea which have different functions:
Epithelium – Keeps the Eye Healthy
It is the outermost layer of the cornea which means that whatever external objects will come in contact with the eyes, they will have to pass the epithelium.
It is made up of regenerative cells which constantly shed and keep regenerating from time to time. It has two primary functions:
It keeps away the dust, debris, water, bacteria and any other type of problem causing impurities from the eyes.
Its smooth surface absorbs essential nutrients and oxygen from our tears.
Bowman’s Layer – Protects the Eye
It is also known as anterior limiting membrane and is made up of protein fibers which are called collagen. It is a strong layer that is between the epithelium
and the corneal stroma and is built to protect the stroma.
Stroma – Gives a Perfection for Clarity
It is the middle layer of the cornea and contributes towards around 90 percent of the overall thickness of the cornea. It comprises mainly of collagen fibrils
and water along with interconnected keratocytes which are used for the repair and maintenance of the cornea. There are 200 to 300 layers of collagen fibrils are
arranged in a parallel manner, and this is the main reason that enables the cornea to be entirely transparent.
Descemet’s Membrane – Protects from Infection
It is the fourth layer of the cornea which is quite thin but very strong as it helps protect against any infections or injuries. It is also known as a posterior
limiting membrane. It is also made up of collagen fibrils and separates the stroma from the corneal endothelium.
Endothelium – Maintains the Fluids
It is the final layer of the cornea which is in the innermost part. It is made up of mitochondria-rich cells. Bathed by aqueous humor, the endothelium’s primary
function is to keep a perfect balance between the fluids flowing in and out of the cornea at all times. It is the layer that comes directly in contact with the
iris and pupil of the eye.
Problems Affecting the Cornea
Various issues can affect the health of a cornea. Some of them are: