What component is essential for the cornea to remain clear and is responsible for fluid regulation?

The endothelium is the component essential for maintaining the clarity of the cornea and plays a critical role in fluid regulation. This thin layer of cells located on the inner surface of the cornea is responsible for pumping excess fluid out of the stroma, which is the thick, middle layer of the cornea. By actively regulating fluid levels, the endothelium prevents swelling and keeps the cornea transparent.

If fluid were to accumulate due to a malfunction or damage to the endothelium, it would result in corneal edema, leading to cloudiness and a loss of vision. Therefore, the endothelium's role in maintaining proper hydration levels is vital for corneal transparency and overall eye health. The other layers of the cornea, while important for structural integrity and protection, do not play the primary role in fluid regulation like the endothelium does.