What is keratoconjunctivitis sicca? - Tears help clean, nourish, reduce bacteria, and help in healing. Without tears a condition called keratoconjunctivitis sicca (KCS) develops, otherwise known as "dry eye". Tears are especially important to the cornea of the eye. The cornea is the transparent, dome shaped, covering over the eye. The cornea is usually clear and shiny because it doesn't have any blood vessels; that way light can shine through uninterrupted. Oxygen and nutrients cannot be delivered to the cornea through blood vessels; so it is delivered through the three layered tear film. Each layer of the tear film does it's job to help protect and nourish the cornea but the middle aqueous layer is the layer produced by the main tear gland and a gland in the third eyelid - this is the layer that is decreased in patients with dry eye.
What causes dry eye syndrome? - KCS is thought to be caused by some viral infections like canine distemper, as well as some immune mediated diseases. There is also thought to be a connection between hypothyroidism and dry eye. Sulfa-containing drugs can produce a toxic effect and cause dry eye; stopping the use of these drugs might result in improvement of the dry eye condition but in some cases the condition is irreversible. In most cases the cause of dry eye syndrome is not known.
What are the symptoms of dry eye? - Symptoms include but are not limited to:
- Eyes appear dull and dry.
- Recurrent eye infections and/or corneal ulcers.
- Thick, green discharge that sticks to the hair around the eye.
- Winking eyes.
- The nostrils will seem crusty.
If you notice any of these symptoms in your dog contact your veterinarian for an eye exam. Failing to treat dry eye will lead to partial or complete blindness.
Diagnosing KCS - Dry eye is diagnosed with a Schirmer tear test that measures the tear production in the eye. Your veterinarian may also want to do a fluorescein stain test to look for corneal ulcers.
Dry eye treatment - 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.
Some of the common dry eye medications include:
- Cyclosporine (Optimmune) is an immune suppressing drug that gives relief and in some patients increases tear production.
- Artificial tear ointments and drops. Ointments remain in contact with the cornea longer and are usually recommended over drops.
- Topical antibiotic eye drops like neomycin-bacitracin-polymyxin (NPD). Tears will usually wash mucus from around the eyes, due to absent tears there is a build up of mucus that will cause bacteria to grow. Using an antibiotic drop will help keep bacterial growth under control. It is also important to keep the eyes wiped clean with a warm wash cloth.
- Corticosteroids should not be used if a corneal ulcer is present because they will decrease healing time.
- A surgical process is available where a duct from a saliva producing gland is transplanted into the upper eyelid. This procedure is rarely done.
Things to consider:
- The prognosis is guarded.
- Treatment is needed for the life of the animal.
- Medications must be given on a regular basis in order for the treatments to work.
- Failure to treat will result in blindness.
References:
www.peteducation.com, Keratoconjunctivits Sicca
eyevet.info, Keratoconjunctivitis sicca (KCS) or Dry Eye
Common Diseases of Companion Animals, Alleice Summers, MS, DVM (Mosby, Inc. 2002)
