Corneal Sequestrum in Cats

A corneal sequestrum is a discrete area of dead tissue that forms on the surface of a cat's eye, most often appearing as a dark brown or black patch on the cornea. The tissue becomes isolated from the healthy cornea around it, and over time the body treats it as foreign material. This condition is almost exclusive to cats and tends to occur following injury, chronic irritation, or certain viral infections affecting the eye. Owners often first notice a dark spot on the eye itself, sometimes accompanied by squinting, tearing, or a change in how the eye looks. The appearance can be striking—a small brown or black island on the clear part of the eye—and it may prompt worry about whether the eye is damaged or infected. In some cases the area causes discomfort, while in others the cat shows few outward signs. This page explores what signals may accompany a corneal sequestrum, what is happening in the tissue of the cornea, how the condition is investigated and confirmed, and what approaches exist for managing it. The course and outlook vary depending on the underlying cause, the size and location of the affected area, and how the eye responds over time.