Keratoconjunctivitis Sicca - Beyond Cyclosporine

Keratoconjunctivitis sicca (KCS) or “dry eye” is often considered as simply an aqueous tear deficiency. However, the tearfilm relies on a complex secretory, distributional, and drainage system which must act together to protect the corneoconjunctival surface. In most KCS cases, treatment with cyclosporine is curative. Unresponsive cases require further discussion.

The five main treatment goals:

1. Resolve the underlying cause. Although autoimmune dacryoadenitis is most common, consideration of the “damnit” list, careful assessment of history and clinical signs, and appropriate diagnostic testing will facilitate recognition of other causes, expedite treatment, and improve prognosis.
2. Minimize further tear loss and maximize tear distribution. Dogs with marginal tear production can be made more comfortable by correction of mild ectropion or entropion, removal of distichia, or reduction of palpebral fissure size.
3. Stimulate tear production. Tear replacement is no substitute for increased tear production. Cyclosporine (CsA) is an effective drug for this purpose, reduces immune-mediated destruction of the lacrimal gland, is directly lacrimogenic, and promotes mucin production. These three functions and knowledge that immune-mediated dacryoadenitis is the most common cause of KCS make treatment with CsA the first choice. Its direct lacrimogenic effect relies on frequent application, while immunosuppression and remodeling of glandular tissue require more chronic use. Therefore, in most cases this drug should be instituted twice daily and the patient rechecked in approximately 2 weeks. The client should be instructed to apply CsA until the time of recheck examination.
4. Supplement the tearfilm. “Artificial tears” provided as aqueous solutions, viscous polymer or methylcellulose solutions, and petrolatum ointments do not replace all functions served by tears and can dilute naturally-produced tears. These products and their preservatives also can cause surface irritation. Until CsA improves clinical signs, I use preservative-free hyaluronic acid (http://www.imedpharma.com/), which is mucinomimetic and extremely well tolerated in dogs and cats.
5. Treat secondary infection. Secondary infection is common when tear quality or quantity declines and can be treated with a well-tolerated, broad-spectrum antibiotic that controls overgrowth of grampositive flora. Triple antibiotic ointment is an excellent choice. This should be discontinued as soon as clinical signs improve. [...]