Cornea

A dome-shaped, transparent, avascular tissue covering the front of the eye. It is composed of five layers: squamous epithelium, Bowman's membrane, stroma, Descemet's membrane, and endothelium. Refraction of light contributing to eye's focusing ability is its characteristic function. It contains unmyelinated nerve endings which are responsible for the high sensitivity of the tissue.

Source: NCI Thesaurus (C12342).