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Corneal epithelial cell
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The cornea is the clear window at the front of the eye, and it is made of five layers. The first one, the one facing outward, is the corneal epithelium. It is a nonkeratinized stratified squamous epithelium, meaning several rows of flat cells stacked on top of each other, without the tough keratin layer that skin has. It is the layer that faces out: tears reach it first, and so does dust. And it replaces itself quickly.
It does two things at once. It keeps foreign bodies and substances from getting in, and at the same time it lets nutrients through, oxygen among them, which reach it from the tear film that sweeps across its surface.
That last part is no small detail. The cornea has no blood vessels. So it is nourished by diffusion, that is, by simple movement from where there is more to where there is less: from the tears on the outside and from the aqueous humor, the fluid in the front chamber, on the inside.
In brief
The corneal epithelium is the first of the cornea's five layers, a nonkeratinized stratified squamous epithelium that regenerates quickly and sits directly against the tear film.
It is the layer that faces out: tears reach it first, and so does dust.
Its two jobs are to keep foreign bodies and substances out and to let in nutrients, such as oxygen, from the tears.
The cornea has no blood vessels: it is nourished by diffusion, from the tears on the outside and the aqueous humor on the inside.
Sources (2)
- National Center for Biotechnology Information, StatPearls PublishingHistology, Eye, StatPearlsPublished
- National Center for Biotechnology Information, StatPearls PublishingAnatomy, Head and Neck, Eye Cornea, StatPearlsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
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