The cornea, although it is thin, is made up of five different layers:
- Epithelium: the outermost layer that provides protection. This layer is home to thousands of nerve endings, which is why it is so painful when you scratch or injure the front surface of your eye.
- Bowman's Membrane: strong protective layer directly below the epithelium
- Stroma: the thickest of all the layers, the stroma is made up of collagen, water and connective tissue. It helps strengthen the cornea and helps keep the tissue flexible and transparent
- Descemet's Membrane: a thin protective layer composed of collagen
- Endothelium: the innermost layer of the cornea that contains specialized pumps to help pump excess fluid out of the stroma
The cornea is the only human tissue in the body that does not contain blood vessels. Instead of receiving nutrients from blood vessels like the rest of the tissues in our body, the cornea gets its nourishment from a fluid inside the eye called the aqueous humor and also from tears. Our tears are not only important for nourishment, but they also help to focus the light as it enters the eye so we can see clearly.
What are the most important functions of the cornea?
- Protection: the cornea protects against dirt, dust, germs and pathogens...anything that could enter the eye
- Focusing Power: the cornea is responsible for 60-75% of the eye's total power and plays a crucial role in clear vision
- UV Filter: the cornea helps protect the lens and the retina from harmful UV rays