KCS or Keratoconjunctivitis sicca is also known as “Dry Eye” is a painful condition caused by the inadequate production of tears. While tears are essential to the comfort of the eyes, they do much more than just provide lubrication. They contain anti-bacterial proteins, sugars, salts, oils, water, and oxygen; all of which provide nourishment to the eyes. Tears also flush out irritants and infectious agents. Two lacrimal glands in the eyes are responsible for the secretion of tears.
Keratoconjunctivits sicca is the technical term for “Dry Eye”. ‘Kerato’ refers to the cornea, ‘conjunctivae’ are the pink membranes of the eye, ‘it is’ means inflammation, and ‘sicca’ means dry. The eyes become irritated without tears, and the
conjunctival tissue around the eyes become red. Over time, the cornea may turn brown in effort to protect the eye and there is often a gooey yellow discharge in and around the eyes of a patient suffering from KCS.
KCS occurs when there is a deficiency in the water part of the tear film, which accounts for 95% of the tear fluid. Without the proper percentage of water, there is a surplus of oil and mucous present resulting in the typical gooey yellow discharge that is characteristic of KCS.
Causes of KCS:
- Congenital defect resulting in lack of tear production
- Use of Sulfa type drugs
- Removal of the lacrimal glands ie) during a surgery to correct ‘Cherry Eye’
- Anesthesia, if the eyes aren’t lubricated
- Inheritance due to breed disposition, which is an immune mediated condition causing destruction of the tear gland-Damage to the facial nerve (Cranial Nerve VII)
- Middle ear infection
- Bacterial or viral infections
- Systemic diseases such as hypothyroidism, Cushings, Diabetes Mellitus, Addisons and Distemper.
Symptoms of KCS:
- Pawing or rubbing at eyes
- Eye redness
- Dull, dry, lackluster appearance of the cornea (outer surface of the eyeball)
- Ocular discharge (yellowish green and gooey, collecting in the corners of the eyes and crusting)
- Protrusion of the 3rd eyelid-Hypersensitivity to light
- Excessive blinking
- Impaired vision
- Ulceration or scaring of the cornea
How is KCS Diagnosed
In the early stages, KCS can resemble common variety eye infections (conjunctivitis), therefore it is important to measure the level of tear production in the affected eye(s). The Schirmer Tear Test is the method used in Veterinary Medicine. A strip of paper is inserted in to the lower eyelid for 60 seconds. The moisture of the eye wets the paper and a scale on the strip indicates this measured level of moisture in the eye. 15 mm or greater is considered normal, while 11-14mm is borderline and less than 5mm is severely dry. If a corneal ulcer is suspected, another test may be performed. This test, like the Schirmer test is not painful or dangerous and is called the Florescein Dye Test. A few drops of dye are placed in the affected eye and will highlight any roughened or ulcerated area if the cornea. The veterinarian looks at the eye with the opthalmoscope and will then rinse the remained of the dye out with a gentle stream of water.
How is KCS treated?
There are several products available to help treat and manage KCS. Cyclosporin is an immunomodulating drug that is used in patients recovering from organ transplants. Used as an eye drop it helps to supress immune destruction and restore tear production (provided the lacrimal glands are still functioning). Cyclosporin has been very successful in treating KCS and only has to be applied once or twice daily. There are other products on the market as well which your veterinarian will consider in determining the best treatment plan for your pet. Artificial tear products and antibiotics are often added to the treatment regime initially as the low tear production associated with KCS reduces the ability of the eye to wash infectious agents away, making the patient prone to infections.
Immune mediated dry eye is a chronic condition that isn’t curable but can usually be managed with lifelong treatment. If medication doesn’t alleviate the patient’s symptoms, there are several surgical options that may help. Your veterinarian will advise you when and if surgery may be the most appropriate form of treatment for your pet.
Prognosis for KCS affected patients varies depending on the cause of the condition and the compliance of the owner in following the treatment therapy. Dogs that have immune mediated KCS generally need to be treated daily for the rest of their lives. While a complete cure isn’t always possible, effective management of this condition is quite possible, but it is a long term commitment and can be challenging for owners.