Identify the structural and functional characteristics of the cornea.

The cornea is a clear, dome-shaped surface that covers the front of the eye. It plays a key role in vision by helping to focus light onto the retina. Here are its structural and functional characteristics:

Structural Characteristics:

1. Transparency: The cornea is a clear tissue allowing light to pass through. This is due to the arrangement of collagen fibers and the absence of blood vessels.
2. Layers: The cornea is composed of five layers. From the outermost to the innermost, these are: the epithelium, Bowman's layer, the stroma, Descemet's membrane, and the endothelium.
3. Nerve Supply: The cornea is the most densely innervated tissue in the body, which makes it highly sensitive to pain.

Functional Characteristics:

1. Light Refraction: The cornea provides 65-75% of the eye's focusing power by bending or refracting light that enters the eye.
2. Barrier Function: The cornea acts as a barrier against dirt, germs, and other particles that can harm the eye.
3. Filter: The cornea also filters out some amounts of the sun's ultraviolet light, providing some protection to the eye.