A corneal sequestrum is a condition peculiar to the cat where corneal stromal necrosis occurs. The dead stroma becomes pigmented and in most cases the plaque extrudes and sloughs leaving a corneal ulcer with a pigmented crater. Various names have been given to this lesion since it first description in 1965. These include corneal mummification, the isolated black lesion, corneal nigrum, keratitis nigrum, focal degeneration of the cornea, corneal necrosis, primary necrotising keratitis and corneal sequestration or sequestrum. The cause of the corneal necrosis is unknown. Some authors suggest a primary corneal dystrophy, while others suggest that the necrosis is secondary to a plethora of factors which make the cornea vulnerable. The origin of the black discolouration of the desiccated stroma is thought to be epinephrine products in the tears which adsorbs into the degenerative stroma.