Cornea is the first optical element in the path of light entering the eye, playing a role in image formation and protection of the eye. The smooth optical surface of the cornea is maintained by a tear film, which adheres to a variety of microprojections. The present study aimed to examine and compare the main features of the corneal epithelial surface of a variety of vertebrate species (Rana ridibunda, Acanthodactylus boskianus, Falco tinnunculus and Gerbillus gerbillus) inhabiting different environments, by scanning electron microscopy. The mean epithelial cell densities of the present species were 3817±423, 5345±1247, 6234±2136 and 1789±216 cells/ mm², respectively. The corneal epithelium of all studied species showed similarity in that the apical cell surfaces possess regular polygonal cells and a variety of microprocesses as microholes, microplicae and microridges. Microvilli are also described. According to the densities of these microprocesses, three polymorphic cell types (light, medium and dark) appeared in R. ridibunda, A. boskianus and F. tinnunculus. However, in G. gerbillus, two cell types only were observed.  In conclusion, variation in the structure of the corneal epithelial cells appears to be related to the living environment of each species, such as aerial, terrestrial and aquatic ones, in addition to some phylogenetic trends.