Corneal ulceration is loss of the corneal epithelium (the outermost cells of the cornea) with exposure and possibly loss of the underlying corneal collagen. Corneal epithelium is constantly being lost and replaced, and its health and thickness depend on a delicate balance between cell loss and regeneration.
Causes of excessive cell loss include injury from ingrown or misplaced eyelashes, exposure to foreign material, chemicals, heat or smoke, infections with certain viruses and bacteria, and from trauma such as cat scratches. Decreased tear production ("dry eye" or keratoconjunctivitis sicca) and inadequate blink responses may cause corneal ulceration. The potential causes of corneal ulcers are almost too numerous to list.
Corneal ulceration can affect any animal; however, those breeds of cats with more protuberant (prominent) eyes and larger eyelid openings are at increased risk. Some older animals may heal more slowly and, therefore, may have ulcers that are more difficult to treat.
Corneal ulceration is a painful and potentially vision-threatening condition. Early diagnosis and appropriate treatment is usually rapidly curative. Complicated cases can progress to full thickness or perforating ulcers with serious effects on vital structures within the eye.What to Watch For Squinting
Mucus or pus draining from the eye
Cloudiness of the cornea
Inflamed, red conjunctiva (the normally pink tissue surrounding the cornea and lining the eyelids)
Inability to see the eye because the third eyelid is covering it
Rubbing at the eye
Veterinary care includes diagnostic tests and subsequent treatment recommendations.
Diagnostic tests are needed to recognize corneal ulceration, any underlying cause and to exclude other diseases. Tests may include:
Thorough ocular examination with special attention to the eyelashes, eyelids and blink reflex, status of the cornea and interior of the eye.
Fluorescein staining of the cornea to assess ulcer size, depth and character. Fluorescein is a dye that adheres to the central layer of the cornea and makes the ulcerated area become bright green.
Schirmer tear test to measure tear production
Cytology, culture or PCR (DNA testing) and IFA assays of ocular samples for the presence of infectious agents such as bacteria and viruses
Treatments for corneal ulceration may include any of the following:
Removal or treatment of the underlying cause
An antibiotic eye drop or ointment to treat or prevent infection of the cornea
Atropine to dilate the pupil and relieve pain from uveitis (inflammation of the inner layers of the eye) and spasm of the iris
An Elizabethan collar to prevent the cat from rubbing the eye and making the ulcer worse
Surgery to treat a rapidly progressive or deep corneal ulcer. Surgery may involve applying a soft contact lens or suturing the eyelids partially closed to bandage the eye, or the placement of conjunctival grafts over deep lesions.
Oral antibiotics for serious infections of the cornea, and oral anti-inflammatory drugs (such as aspirin) if inflammation is present within the eye.
At home, administer all veterinary prescribed medications and follow up with your veterinarian within a few days of the original diagnosis. Take care that your cat doesn't rub at the eye or cause any extra trauma to the healing ulcer. Leave the Elizabethan collar on at all times until your veterinarian approves its removal.
Observe the eye for signs of worsening, especially cloudiness of the cornea, increased or altered ocular discharge, continued squinting or more obvious inflammation of the conjunctiva, which is the delicate lining in the eyelids and covering part of the eyeball.
Examine your cat's eyes regularly and call your veterinarian if you note any pain or color change. Try not to get anything other than saline or clean water in your cat's eyes. For example, avoid shampoos, soaps and any other household cleaners. Do not attempt to remove foreign material from your cat's eye. Instead, seek urgent veterinary care.