Keratoconjunctivitis sicca or KCS is an eye disease caused by decreased tear production or increased tear film evaporation commonly found in people and small animals. A more common term is "dry eyes".

Keratoconjunctivitis sicca is Latin and the literal translation is "dryness of the cornea and conjunctiva". In man, the typical symptoms are sandy-gritty eye irritation that gets worse as the day goes on. The symptoms are caused by a loss of water from the tears that results in tears that are too "salty" or hypertonic. The best treatment strategies are designed to rehydrate the tears and eye surface, and include hypotonic, electrolyte-balanced tears, punctal plugs, and moist chamber spectacles. The inflammation that occurs in response to tears film hypertonicity can be suppressed by mild topical steroids or immunosuppressants such as cyclosporine, but these treatments have not been shown to help symptoms. In animals thicker medications are needed because most owners cannot reapply eye medicines more than 3-4 times a day.

Keratoconjunctivitis sicca usually occurs in people who are otherwise healthy. It is more common with older age, because tear production decreases with age. In rare cases, it can be associated with rheumatoid arthritis, lupus erythematosis , and other similar diseases. It may also be caused by thermal or chemical burns.