"Dry Eye"
(Keratoconjunctivitis Sicca or KCS)

Tears are essential to the comfort of our eyes, but they do more than just provide lubrication. Tears contain anti-bacterial proteins, salts, sugars, and even oxygen to nourish the eye. Tears flush away irritants and infectious agents that are frequently in contact with our eyes. Since the outer portion of the eye does not have a blood supply, tears must bring nutrients to the eye and remove metabolic waste.

Tears consist of oil secreted by the eyelid glands, mucus, and water. Tears are secreted by two lacrimal glands in dogs and cats: one just above the eye and the other is located in the third eyelid (the nictating membrane).


When tear production is reduced, eyes become irritated, the conjunctival tissues around the eyes get red, the cornea will turn brown in an effort to protect the eye, and a thick, yellow discharge covers the eye. Without the protection of tears, the eyes become dry and irritated, often develop infections and the cornea can become ulcerated. Eventually, the cornea can become permanently scarred, or develops blood vessels and pigments over its normally transparent surface, leading to blindness.

Keratoconjunctivitis sicca means the eye is dry. “Kerato” refers to the cornea or clear covering of the eye. “Conjunctivae” are the moist, pink membranes of the eye. “Itis” means inflammation and “sicca” means dry. KCS means inflamed, dry cornea and conjunctiva. It occurs when there is a deficiency in the water portion of the tear film which normally accounts for 95% of the tear volume. Without the water, one is left with oil and mucus; resulting in the yellow eye discharge characteristic of this condition.

• Redness of the eyes due to inflammation - your dog may squint and rub at its eyes
• A thick sticky yellowish discharge from the eyes
• Ulceration of the cornea
• A dull or cloudy cornea early in the disease
• Blindness due to corneal pigmentation and scarring later in the disease.

*Dry eye is most common in middle aged and older dogs.*

*The breeds of dog most prone to dry eye are: West Highland White Terrier, Cavalier King Charles Spaniel, Cocker Spaniel, Shih Tzu, Miniature Schnauzer, Pekingese, Bulldog, Pug and Lhaso Apso.*


A dog with keratoconjunctivitis sicca

There are many causes of dry eye. The following are some possible reasons for KCS:

• Distemper infection attacks all body interfaces with the environment including the eyes. Dry eye is part of the collection of symptoms that can occur with distemper infection.
  
  
• In cats, Herpes upper respiratory infection can lead to chronic dry eyes.
  
  
• There could be a congenital lack of tear producing gland tissue.
  
  
• Exposure to sulfa containing antibiotics (such as Trimethoprim sulfa combinations) can lead to dry eye.
  
  
• Anesthesia will reduce tear function temporarily (thus eyes are lubricated with ointment by the veterinary technician.)
  
  
• Removal of the third eyelid tear producing gland (instead of replacing the gland in its proper location) during surgery for Cherry Eye can lead to KCS. Also, too much damage to the gland prior to proper gland replacement can cause dry eye.
  
  
• Head trauma in the area of one of the tear producing glands can lead to KCS.
  
  
• The most common cause of KCS appears to be immune-mediated destruction of the tear producing gland tissue. Certain breeds are predisposed including the American Cocker Spaniel, Miniature Schnauzer, and West Highland White Terrier.

To diagnose KCS it is important to actually measure the tear production to determine how dry the eyes are. The test that accomplishes this is called the “Schirmer Tear Test.”



To perform the test, a strip of special paper is inserted just inside the lower eyelid in the outer corner of the eye for 60 seconds. The moisture of the eye will wet the paper. At the end of the 60 second period, the height of the moistened area is measured. A height of 15mm or more indicates normal tear production. A height 11-14mm is a borderline result. A height of less than 10mm is dry. A height less than 5mm is severely dry.

Treatment of dry eye may be either medical or surgical. Medical therapy is usually effective and is commonly attempted prior to resorting to surgery. It may include:

• Treatments to increase tear production
• Artificial tears.
• Antibiotics
• Corticosteroids in some situations

The goals in treating KCS consists of lubricating the eye, tear replacement, stimulating tear production, reducing bacteria overgrowth, and reducing inflammation. This is done with topical eye drops and/or ointments.

Until recently, tear replacement formulas and mucus dissolving agents were the only medications available to treat KCS. These are still helpful but require an impractical frequency of administration. A breakthrough came with the discovery of cyclosporine topical therapy to control the immune mediated gland destruction.

Cyclosporine is an immuno-modulating drug that had already been found to be beneficial for organ transplant patients. When applied as an eye drop or ointment, it suppresses the immune destruction that is the most common cause of KCS and tear production is restored. The success of this treatment plus its convenient dosing interval (twice a day) has made the medication Optimmune the primary treatment for KCS.


Optimmune is the only registered product which treats the cause of the problem, not only the symptoms, by:

• stimulating the tear glands to resume normal tear production
• halting the immune destruction of these glands
• helping to reduce inflammation of the eye

Optimmune is usually applied twice daily to the eyes for the remainder of the dog's life. It has been found to be effective in over 80% of dogs with initial Schirmer Tear Test readings of greater than 2mm. 50% of dogs with readings of less than 2mm respond to Optimmune, therefore early diagnosis is vital.

Pre treatment		Day 7 of Optimmune therapy
Day 21 of Optimmune therapy		Day 63 of Optimmune therapy

*Do not stop treatment unless told to do so by your veterinarian.*

*Some dogs may take up to 3 months to respond to treatment initially. Most dogs will require lifelong Optimmune therapy.*

After beginning cyclosporine eye drops or ointment, a recheck in 2-3 weeks is recommended to determine the amount of improvement. If the Schirmer tear test is still showing reduced tear production, the frequency of administration of the medication can be changed to 3 times a day, with veterinary approval.

Tacrolimus is another medication able to locally suppress immunity. This product has recently gained popularity in human medicine as a topical anti-inflammatory treatment that is cortisone-free. It does not come in a formulation appropriate for eyes but can be made into one by a compounding pharmacy. It is used in a manner similar to cyclosporine and is generally of similar cost.

Artificial Tears can be purchased in most drug stores. These can be combined with other therapies and are soothing to the eye. However, this product is usually recommended for use 4-6 times a day.


Antibiotic Eye Ointments or Drops are often needed especially when starting treatment for KCS as secondary infections are common when there are inadequate tears to wash infectious agents away. These products do not increase tear production but may be important part of treatment, especially early in therapy.




Mucomyst® Eye Drops are made from a respiratory product used to dissolve thick mucus. In an eye formula, Mucomyst (active ingredient Acetylcysteine) helps remove the thick eye discharge that accompanies dry eye.

Severin’s Solution is a mixture of Mucomyst, pilocarpine, artificial tears, and antibiotic which can be mixed together and prescribed by a veterinarian. The “recipe” originated in an article published by a veterinary ophthalmologist named Dr. Severin in 1996. Many animal hospitals create their own solutions based on this recipe.

There is a surgical solution to KCS though it is a delicate procedure in general only done by veterinary ophthalmologists. This is called the Parotid Duct Transposition. The parotid duct is the salivary gland on either side of the facial cheek. It produces saliva which is carried to the mouth via a long duct. This duct can be carefully dissected out and moved so as to deliver saliva over the eye. Saliva actually makes a reasonable substitute for tears, though in time, some mineral deposits will form on the eye surface and eye drops may be needed to control this. The dog’s eyes will water when he is fed and facial wetness may be objectionable.

The pigment on the surface of the cornea resulting from long standing KCS is like the lens of dark sunglasses and interferes with a dog’s vision especially in dark situations. If tear function is restored, vision may also be restored via a procedure called a Superficial Keratectomy where the pigmented surface of the cornea is sanded away. As with the parotid duct transposition, a veterinary ophthalmologist is probably best suited to perform such a procedure.