Written by Emily Moeller, DVM, DACVO
What is dry eye?
The surface of the eye is covered with tears that are produced by glands located around the eye. Tears provide oxygen, sugar, proteins, and healing factors to the surface of the eye. Dry eye is a disease of low tear production.
What causes dry eye?
The most common cause of dry eye is inflammation within the tear glands. The cause of the inflammation is usually unknown. Inflammation in the tear gland interferes with tear production, and if unchecked, can cause complete and irreversible loss of gland function.
Why does dry eye matter?
The cornea (the clear dome on the surface of the eye) relies on tears for nutrition and protection. When tear production is low, the cornea does not receive the nutrients that it needs to survive. The cornea will respond by developing inflammation and scar tissue to protect itself. In the short term this can be uncomfortable, however in the long term it can lead to vision loss as scar tissue and inflammation accumulate on the cornea.
How will I know if my dog has dry eye?
Common signs of dry eye include redness, mucoid ocular discharge, squinting, and rubbing. Many dogs with dry eye will develop recurrent conjunctival infections due to bacterial overgrowth in the ocular discharge. Dry eye can be diagnosed with a simple test performed by your veterinarian called a Schirmer tear test.
How is dry eye treated?
Most dogs with dry eye show significant improvement with use of tear stimulating medications called ‘lacrimostimulants’. Artificial tear drops can be useful, however it is important to remember that artificial tears alone will only mask the symptoms of dry eye and do not treat the underlying inflammatory process. The two most commonly prescribed lacrimostimulants are cyclosporine and tacrolimus. These can be provided by your veterinarian as an ophthalmic ointment or drop. They work by reducing inflammation in the tear gland and stimulating your dog’s own tear production. There is an excellent chance that your dog’s dry eye will improve with medications; however medications are usually required for life.