The lacrimal or tear gland, located at the top outer edge of the eye, produces the watery portion of tears. The nasolacrimal duct system allows tears to drain from each eye into the nose. Disorders of these structures can lead to either eyes that water excessively or dry eyes. They may be congenital (present at birth) or caused by infection, foreign objects in the eye, or trauma.
Disorders of the nasal cavity and tear ducts are not as common in cats as they are in dogs. However, a few disorders occasionally are seen in this species.
Occasionally cats will experience a chronic overflow of tears due to an obstruction of the nasal duct called epiphora. This is more common in Persian and Himalayan breeds. In most cases, there is no reason for concern when this occurs, as it does not lead to any medical problems. However, if appearance is an issue, the condition can be corrected surgically.
Inflammation of the tear sac (called dacryocystitis) is rare in cats. The tear sac is located within the lower, inner corner of the eye. Inflammation of the tear sac is usually caused by obstruction of the tear sac and the attached nasolacrimal tear duct by inflammatory debris, foreign objects, or masses pressing on the duct. It results in watering eyes, conjunctivitis that is resistant to treatment, and occasionally a draining opening in the middle of the lower eyelid. If your veterinarian suspects an obstruction of the duct, he or she may attempt to unblock it by flushing it with sterile water or a saline solution. X‑rays of the skull after injection of a dye into the duct may be necessary to determine the site, cause, and outlook of longterm obstructions. The usual therapy consists of keeping the duct unblocked and using eyedrops containing antibiotics. When the tear duct has been irreversibly damaged, surgery may be necessary to create a new drainage pathway to empty tears into the nasal cavity, sinus, or mouth.
The condition known as dry eye results from inadequate tear production. It often causes persistent mucus and pus-filled conjunctivitis and slow-healing sores (ulcers) and scarring on the cornea. Dry eye is not common in cats but has been associated with longterm feline herpesvirus-1 infections. Topical therapy consists of artificial tear solutions, ointments, and other medications. In longterm dry eye resistant to medical therapy, surgery may be required to correct the condition.