The term "dry eye" can be a little confusing since one of the most common symptoms is excessive watering or tearing! It makes more sense, though, when you learn that the eye makes two different types of tears.
The first type, called lubricating tears, is produced slowly and steadily throughout the day. Lubricating tears contain a precise balance of mucous, water, oil, nutrient proteins, and antibodies that nourish and protect the front surface of the eye.
The second type of tear, called a reflex tear, does not have much lubricating value. Reflex tears serve as a kind of emergency response to flood the eye when it is suddenly irritated or injured. Reflex tears might occur when you get something in your eye, when you are cutting onions, when you cry, or when you accidentally scratch your eye. The reflex tears gush out in such large quantities that the tear drainage system cannot handle them all and they spill out onto your cheek. Still another cause of reflex tearing is irritation of the eye from lack of lubricating tears. If your eye is not producing enough lubricating tears, you have dry eye syndrome.