Corneal Disease in Cats

The cornea is a thin, clear layer that covers the pupil, iris, and anterior chamber of the eye. Corneal dystrophy causes white or gray localized lesions to appear in the cornea. The condition can lead to total blindness depending on the area where the lesions appear.

Corneal disease, also known as corneal dystrophy, is a relatively rare condition in cats that causes varying levels of vision loss and symptoms in the eyes. Both eyes are normally affected by the disease in the same manner. Corneal dystrophy is inherited and isn't accompanied by any other diseases or conditions. It most often occurs in domestic Shorthair and Manx breeds of cats with symptoms typically appearing between four months and 13 years of age.

Corneal dystrophy is categorized into three types: stromal corneal dystrophy, epithelial corneal dystrophy, and endothelial corneal dystrophy. Each type is characterized by different symptoms.

Stromal Corneal Dystrophy

• Symptoms occur in the stroma, the middle layer of the cornea
• Gradual loss of vision due to advanced diffuse opacity
• White, gray or silver rings around the cornea that are either round, oval or shaped like a donut

Epithelial Corneal Dystrophy

• Symptoms occur in the epithelium, the upper portion of the cornea
• Normal vision
• Corneal spasms
• Onset typically occurs between four months and one year of age
• Gray or white rings or opacities on the cornea
• Progresses slowly
• Corneal ulcers, fluid blisters on cornea
• Pain in the eyes if ulcers are present

Endothelial Corneal Dystrophy

• Symptoms occur in the endothelium, the deepest layer of the cornea
• Impaired vision as the disease progresses
• Normally occurs in young kittens
• Corneal swelling
• Corneal ulcers, fluid blisters on cornea
• Pain in the eyes if ulcers are present

Each type of corneal dystrophy is attributed to a separate cause.

• Stromal corneal dystrophy is caused by fat deposits in the middle portion of the cornea, the stroma
• Epithelial corneal dystrophy is caused by innate abnormalities of the cornea
• Endothelial corneal dystrophy is caused by the breakdown of the corneal lining

Once a pet owner suspects that his or her cat has corneal dystrophy, it's important to note all of the symptoms that the cat is experiencing and when the symptoms first began in order for the veterinarian to diagnose the correct type of corneal dystrophy.

Once the veterinarian has the cat's complete health history, the veterinarian will perform a complete exam of the cat. This will include an ophthalmic examination. During an ophthalmic examination, the veterinarian or veterinary ophthalmologist will look at the cat's eyes and surrounding tissue. The veterinarian will observe how the cat moves around the room, if he or she is able to watch a small object that is moved in front of their eyes and if blinking occurs when an object is brought close to the eyes. A slit lamp microscope will be used to view any swelling, rings or other abnormalities in the cornea.

A fluorescein stain will be dropped into the cat's eyes and a blue light will be utilized. The stain glows under the blue light, helping the veterinarian to look for the shape of the cornea, any corneal ulcers, and any corneal abrasions that are present in the eye. Other tests, such as a complete blood count, urinalysis, and glaucoma test, will also be performed to rule out other conditions that may be causing swelling before diagnosing the type of corneal dystrophy. Any corneal ulcers will be tested for culture and sensitivity in order to determine the type of bacteria causing the ulcer and the best antibiotics for treatment.

Treatment will be based on the type of corneal dystrophy and the symptoms that are present. Though there is no cure for corneal dystrophy, treatment can halt the opacification for as much as seven years.

Antibiotics

Corneal ulcers will be treated with antibiotics. The veterinarian will prescribe an antibiotic that is sensitive to the bacteria in the eye based on the sensitivity and culture results. The antibiotics will treat the ulcers and any accompanying pain.

Surgery

The veterinarian may recommend surgery to treat corneal dystrophy. Surgery may be used to remove any epithelial corneal tags, facilitate a corneal transplant, or to perform flap surgery of the conjunctiva or outer lining of the eye and inside of the eyelid. If treatment options are no longer treating the corneal dystrophy or if the condition has returned after treatment, the veterinarian may need to perform an enucleation. During enucleation, the eye will be removed from its socket, leaving the muscles and other nearby tissues, before suturing the outer portion of the eyelids closed.

After the initial treatment, your cat will likely still have cloudiness in its eyes. However, your cat will likely retain all of its vision despite having corneal disease. If you notice that your cat has pain in the eyes you will need to contact your veterinarian immediately. This can be a warning sign that ulcers are developing in your cat's eyes. It is important to follow your veterinarian's recommendations for treatment at home and follow the medication guidelines. If you notice any significant changes in your cat's behavior anytime after treatment, notify your veterinarian as this can be a symptom of underlying conditions.