Causes
Many causes: infections (common in cats due to herpesvirus), allergies, a foreign body, irritants, blocked tear ducts, or secondary to another eye disease.
Diagnosis
Eye examination. The vet may stain the cornea to rule out ulcers and measure tear production.
Treatment
Depends on the cause: antibiotic or anti-inflammatory eye drops, removal of foreign bodies, treatment of the allergy. NEVER use human eye drops without prescription — some make certain injuries worse.
Prevention
Eye hygiene, avoiding irritants, vaccination (in cats), and treating allergies.

