Rabbit, dog, and human corneal epithelium was studied in tissue culture for the effect of epinephrine at 0.001% concentration. Degenerative changes in the epithelial cells appeared within 24 to 48 hours. Loosened cells and increased optical density of cell nuclei were followed by increased granularity and vacuolation. Melanin or melanin-like material was deposited after 216 to 240 hours, and there was formation of giant vacuoles. The pigment was not only extracellular but present in the cytoplasm and nuclei.
Krejci L, Harrison R. Epinephrine Effects on Corneal Cells in Tissue Culture. Arch Ophthalmol. 1970;83(4):451-454. doi:10.1001/archopht.1970.00990030451012