The normal number of corneal endothelial cells varies according to age. The number of corneal endothelial cells is about 3,000-4,000 before the age of 30, 2,600-2,800 between the ages of 50 and 70, and the normal range is between 2,150-2,400. The innermost layer of the cornea is the corneal endothelium, which is a layer of hexagonal cubic epithelium. This layer of cells is relatively “short and fat”, with a height of about 50 μm and a width of about 20 μm, with abundant organelles in the cytoplasm, and with inter-cellular connections, which are mainly interlocking. These cells are tightly interlaced in the form of a mosaic and have a good protective barrier. The density of corneal endothelial cells begins to decrease with age. The density of the corneal endothelium is 3,000-4,000/mm at 10 years of age and about 2,500/mm at 70 years of age. Corneal endothelial cells do not regenerate after injury. In daily life, you need to pay attention to avoiding eye injuries and prolonged overuse of the eyes. Pay attention to protect your eyes and develop good eye habits.