The cornea, often referred to as the “black eye,” is the first barrier between the eye and the outside world, and a healthy, clear cornea is very important to people. The corneal endothelium is composed of a single layer of hexagonal cells located at the very back of the cornea. The human corneal endothelium cannot regenerate and is highly susceptible to damage from various physical and chemical factors such as hypoxia, ageing, metabolic disorders, inflammation and intraocular surgery. Endothelial examination allows morphological observation, data processing, and analysis of corneal endothelial cells to assess corneal function for diagnosis of some ocular diseases, assessment of corneal invasion by certain diseases, and guidance of anterior chamber drug delivery and corneal contact lens material selection and wearing style.