Corneal ulceration is loss of the corneal epithelium (the outermost cells of the cornea) with exposure and possible 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 dogs with more protuberant (prominent) eyes and larger eyelid openings are at increased risk. Some older animals may heal more slowly and, therefore, have ulcers that may be 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

Increased tearing

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

Occasional lethargy