The corneal epithelium is the outermost, multilayered structure of the cornea, consisting of 5-7 layers of epithelial cells with a total thickness of approximately 50-60 micrometres, and is the eye's first protective barrier against external factors. The corneal epithelium is a non-corneal stratified squamous epithelium in which three types of cells can be distinguished: superficial squamous cells connected by tight junctions forming a permeability barrier, intermediate wing cells and a basal layer composed of cylindrical basal cells, which are the only cells capable of mitotic division. The basal cells adhere to the basement membrane of the epithelium (Bowman's membrane) via haemidesmosomes, ensuring that the entire epithelial layer is firmly attached to the substrate.
The corneal epithelium is characterised by a unique regenerative capacity - stem cells located in the limbus area (the site of the transition of the cornea to the sclera) undergo continuous division and migration towards the centre of the cornea, where mature surface cells are continuously exfoliated and replaced by new cells in a cycle lasting approximately 7-14 days. This intensive cellular renewal enables rapid healing of superficial epithelial damage, which, if the continuity of the basement membrane is maintained, can occur within 24-48 hours. The corneal epithelium has key protective functions against bacterial and viral infections, maintains the optical transparency of the cornea and provides a smooth surface for a stable tear film. Damage to the corneal epithelium (erosions, erosions) leads to symptoms such as pain, photophobia, tearing and visual disturbances, and chronic epithelial defects can lead to corneal scarring and permanent deterioration of visual acuity.