what causs tears
Tear glands and tear ducts. Dry eyes are caused by a lack of adequate tears. Your tears are a complex mixture of water, fatty oils and mucus. This mixture helps make the surface of your eyes smooth and clear, and it helps protect your eyes from infection.For some people, the cause of dry eyes is decreased tear production.For others it's increased tear evaporation and an imbalance in the makeup of your tears.his mixture helps make the surface of your eyes smooth and clear, and it helps protect your eyes from infection. For some people, the cause of dry eyes is decreased tear production. For others it's increased tear evaporation and an imbalance in the makeup of your tears.