The sequestrum is a dark brown to black plaque which is oval or round and often raised above the corneal surface. Often clients will describe it as 'a scab on the eye'. Application of fluorescein dye to the cornea often reveals dye retention around the edge of the lesion, but the sequestrum itself does not stain. Cats usually develop sequestra on one eye, but bilateral cases occur. The cornea around the sequestrum will be vascularized superficially to varying degrees.
Some cats are present with a faint brown or amber opacity confined to the stroma.
Such a patient may not show signs of discomfort. These are thought to be early lesions, lesions following sloughing or surgical removal and subsequent healing, and re-epithelialization of superficial sequestra. These faint sequestra will usually progress, become more dense, acquire distinct borders, separate from the adjacent and underlying stroma and begin the process of ulceration and irritation with loss of the overlying corneal epithelium. The lesion will become larger, darker and deeper. Corneal perforation and globe rupture can and does occur.