Basal cells and basement membrane
Hello, Liz: The epithelium on the cornea is five cell layers thick. The bottom layer is made of columnar cells and those sit (stand?) on the basement membrane. The basement membrane is extremely thin as compared to a cell. Both the bottom of the epithelial tissue facing the basement membrane and the surface of the basement membrane are hydrophobic according to measurements I made in rabbit eyes several decades ago.
For this reason, a continuous water layer normally cannot form between them as that layer would have a negative disjoining pressure. That term was defined by Derjaguin, a Soviet academician in 1940. It just means that as such a film thins its energy decreases. So the process becomes spontaneous until the film is gone.