There are many non-ulcerative corneal diseases. Some of them can be painful while others can cause blindness. Clinicians should learn to diagnose and, when possible, treat these disease, which include:
· Dermoid – a congenital abnormality presenting with ectopic dermal tissue that may contain irritating hair. Cases are best referred for keratectomy.
· Persistent pupillary membranes – an embryonic membrane that did not fully resorb at birth. Strands of iris tissue may contact the inner cornea, causing a focal opacity.
· Corneal edema may be the result of a corneal ulcer, but may also be caused by endothelial dysfunction or dystrophy. Corneal vesicles may form, and these may cause painful ulceration.
· Corneal pigmentation is the result of chronic irritation of the cornea. The patient should be evaluated for eyelid and eyelash conformation and tear film abnormalities. Topical immunosuppressive treatment and/or corrective surgery may be necessary. Unless the inciting cause is corrected, the pigmentation may progress and cause blindness.
· Corneal mineralization may be due to metabolic disease, genetic predisposition or previous corneal ulceration. Systemic workup for lipid, calcium or endocrinologic abnormalities may be required in some patients.
· Florida spots – a keratopathy of unknown cause. Patients present with multiple round white opacities. The lesions are not progressive and not painful.
· Pannus, or chronic superficial keratitis – cell-mediated autoimmune inflammation of the cornea, characterized by progressive infiltration and pigmentation. German shepherds and related breeds are predisposed, and ultraviolet radiation is a triggering factor. Lifelong immunosuppressive treatment may be required
· Squamous cell carcinoma – cytological samples should be collected from fleshy tissue on the corneal surface. The tumor is very aggressive in cats, and radical surgery may be required.