Cornea, The Living cell without blood

The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber, providing most of an eye’s optical power. It has nerve endings sensitive to touch, temperature, and chemicals. A touch of the cornea causes an involuntary reflex to close the eyelid.

Because transparency is of prime importance the cornea does not have blood vessels. It receives nutrients via diffusion from the tear fluid, aqueous humour, and from neurotrophins supplied by the nerve fibers. It is the only part of a human body that has no blood supply.

The Cornea gets oxygen directly through the air. It is also the fastest healing tissue in the human body. Most corneal abrasions generally heal within 24-36 hours.