Both eyes are affected with this condition which looks like a fleshy growth or pigmented growth on the surface of the cornea. Sometimes a lot of small new blood vessels can be seen growing across the cornea (called neovascularisation). The growing lesion is slowly progressive and can become pigmented with black melanin.

The cause is unknown but it is thought to be an autoimmune disease in which the animals own immune system reacts against something in the surface of the eye (the cornea) causing inflammation.

Because the underlying cause of the disease is not known the condition is likely to recur even if it responds initially to treatment. Initial treatment is usually medical involving the administration of anti-inflammatory drugs such as corticosteroids (by injection or administration onto the surface of the eye). Recently success has been claimed for the use of cyclosporin.

If the cornea becomes heavily pigmented the area may have to be removed by superficial keratectomy to restore sight.