Dry Eye - Keratoconjunctivitis sicca (KCS)
Keratoconjunctivitis sicca (KCS) is the technical term for a condition also known as 'dry eye.' Dry eye is the condition of not having enough tears to lubricate the eye. The most common cause for inadequate tears is immune-mediated.
This means that the animal's own immune system is attacking the tear glands. Other less likely causes include sulfonamide drugs, eye infections, or trauma. Third eyelid gland removal can also be a cause. Certain breeds are predisposed to dry eye, but any breed can get it. Predisposed breeds include Cocker Spaniel, Shih-Tzu, and Lhaso Apso. Dry eye may occur in one eye, but often progresses to the other eye unless 3rd eyelid gland removal is the cause.
What are the symptoms?
The signs of dry eye are thick, yellowish or green discharge from the eyes. Secondary infections in the eyes are common. Tears normally function to remove bacteria and debris from the eyes. Without them, the eye is prone to damage from all of these. To diagnose a case of dry eye, a tear test called the Schirmer tear test is done. This is a small strip of paper placed in the eye for one minute. After the minute, the amount of tears on the strip is measured. This test is also used to evaluate how well treatment is working.
Left untreated, the patient will suffer painful and chronic eye infections. Repeated irritation of the cornea results in severe scarring which shows up as white or brown deposits in the cornea. Corneal ulceration may develop, and can even lead to perforation (explosion) of the eye. When this happens, often the only treatment option is to have the eye removed.
What is the management?
Treatment is aimed at replacing the tears that are no longer being produced. This can be done by replacing the tears with artificial tear or lubricating drops and ointments. Artificial tear solutions available for humans and sold in pharmacies can be used in canines. However, in some dogs, veterinary lubricating ointments seem to last longer. Depending on the severity, these drops are placed in the eyes at regular intervals throughout the day. In most cases, if this is the only treatment, it should be done between 5 and 10 times a day.
Another way of treating is by trying to stimulate the body to produce more tears, and stop the immune system from attacking the tear gland. Cyclosporine or tacrolimus are two eye medications that do this. Once these treatments are started they are usually continued throughout the animal's life. They are given 1-3 times a day depending on how the animal responds. In very severe cases in which treatment was not initiated until late in the disease, cyclosporine or tacrolimus may not work because too much of the tear gland has already been destroyed by the immune system.
It is very important to follow recheck recommendations to evaluate treatment response. Initially, your pet may be on a combination of treatments, as well as antibiotic ointments for secondary bacterial infections.
Surgical options for treatment are limited. In very severe cases, a surgery can be performed which transplants a salivary duct into the upper eyelid area. Saliva then drains into the eye, providing lubrication. This procedure is rarely used, but is an option. If medical treatment fails, a salvage procedure is removing affected eyes. This takes away the pet's pain and discomfort, which can be very significant in severe cases. Most animals learn to adapt well without the eye(s).