Keratoconjunctivitis Sicca (KCS) or “Dry Eye”
Keratoconjunctivitis Sicca is an eye condition where the cornea and conjunctiva become inflamed due to a lack of tear production by the lacrimal gland. Over time, the lack of tear production leads to corneal cloudiness, redness, and pigmentation, which in turn causes vision loss and ocular pain. When tear production is low, the eye also produces a thick yellow/green mucous, which is often mistaken as infection.
1. Causes Of KCS
Most forms of dry eye are spontaneous. However, the disease is more commonly seen in dogs with skin allergies and/or chronic ear disease. In addition, the disorder can be associated with certain oral medications or low thyroid production.
a. Medical Therapy
While KCS can be controlled and tear production can be improved in most patients, rarely is their a “cure” for the disease. Most pets will require therapy for life and maintaining good vision and comfortable eyes is dependent on diligent application of medications.
The mainstay of therapy involves the use of a tear stimulant like cyclosporine (Optimmune) or tacrolimus. Most dogs will respond well to these therapies but response to treatment can sometimes require several weeks to even months of consistent treatment before tear function improves. During this time frame, it is necessary to use artificial tear replacers to keep the ocular surface moist.
b. Surgical Therapy (Parotid Duct Transposition)
For patients that respond poorly to medical therapy, surgically therapy can be performed to help keep the eye moist. The surgical procedure is called a Parotid Duct Transposition and involves moving one of the many salivary ducts from the mouth to the eye. This provides a source of moisture (saliva) for the eye and can both improve comfort and prevent blindness. This is not a perfect solution as it often results in excessive saliva flow and a wet face, and can cause mineral deposition on the corneas. However, it decreases the loss of vision and improves comfort in the majority of patients who have not responded to other therapies.