Corneal sequestrum is a disease affecting the cornea (the clear curved transparent part of the front the eye). The sequestrum is usually an area of degenerated or non-living corneal tissue. This develops after an area of the cornea becomes ulcerated and the ulcer is long standing or non-healing. The area of corneal degeneration often turns light brown to dark brown or black in color. The sequestrum may affect only the outer layers of the corneal stroma (tissue), but in some cases the sequestrum extends deeper into the cornea and may lead to deep ulceration, pain and possibly, corneal rupture.
Feline herpesvirus (FHV-1) is a common cause of eye and upper respiratory infection in the cat. This virus is very common in the cat population, but it is not contagious to people and other species of animals such as dogs. Herpesvirus is easily passed from one cat to another through sneezing, coughing, grooming and/or simply being in close contact with an infected cat. Clinical signs associated with infection can vary greatly between cats. Some cats affected with FHV-1 may only have mild conjunctivitis of one or both eyes. Other cats with more severe forms of the disease may show ocular (eye) and nasal (nose) discharge, conjunctivitis (inflammation of the white part of the eye), coughing, sneezing and corneal ulcers. Corneal ulcers can be very painful and serious enough to cause noticeable scarring on the normally clear cornea. An infected corneal ulcer may even progress to cause perforation (rupture) of the eye.