The cornea is the front clear window at the very front part of the eye. It is a highly specialised structure that gives strength and protection to the eye and prevents any bacteria entering the eye.
The clarity of the cornea is critical for vision
The clarity of the cornea is critical for vision, if the cornea turns cloudy, then you are looking through a misty window and you cannot see very well at all.
The other important part and role it fulfils is to focus light, it provides two thirds of the focusing power of the eye and allows the lens to do the fine tuning of the final one-third of the focusing of the eye.