Cornea

The human eye is a sense or can be said as a visionary organ that reacts to light and allows vision. The eye consists of cornea, pupil, lens, sclera, conjunctiva and more. These all parts help us see clearly.

The cornea is the front part of the eye that is transparent and covers the iris, pupil, and anterior chamber. It lies directly in front of the iris and pupil. The cornea works together with the anterior chamber and lens and refracts light, with the cornea accounting for approximately two-thirds of the eye's total optical power. The average cornea has a center thickness of about 550 microns, or slightly more than half a millimeter. Along with the sclera (white of the eye), the cornea serves as a barrier against dirt, germs and other particles that can harm the eye's delicate components. The cornea also filters out some amounts of the sun's ultraviolet light.

The cornea also plays a key role in vision. As light enters the eye, it's refracted, or bent, by the outside shape of the cornea. The curvature of this outer layer helps determine how well your eye can focus on objects close up and far away. If there is any damage caused to cornea due to disease, infection or injury, the resulting scars or discoloration can interfere with vision by blocking or distorting light as it enters the eye.

The three main layers of the cornea are:

• Epithelium: The epithelium stops outside matter from entering the eye. This layer also absorbs oxygen and nutrients from tears.
• Stroma: It is the thickest layer of the cornea and is located behind the epithelium. Stroma consists of water and proteins that give it an elastic but solid form.
• Endothelium: The endothelium is a single layer of cells located between the stroma and the aqueous humor, the clear fluid found in the front of the eye. The endothelium works as a pump, expelling excess water as it is absorbed into the stroma. Without this specialized function, the stroma could become waterlogged and hazy and