The cause of watery eyes can be due to having dry eyes where the tears do not stick to the front of the eye properly, or to an infection, inflammation or allergic response.
However if the eye is so watery that tears spill out onto the cheek, it is more likely that this is due to a tear drainage problem.
Tears drain out of the eye through small holes in the upper and lower lid called the punctum, and travel along a small tube to eventually drain into the nose. Eyes that water so much that the tears spill onto the cheek will usually have a problem with the positioning of the lower punctum, or a blockage in the tear duct connecting to the nose.
If the tear duct is slightly blocked, it may be possible to clear it by syringing – forcing fluid along the tear duct to clear it. If the tear duct is not blocked, but the punctum is not in the correct position, a minor surgical procedure may restore normal tear drainage and relieve the problem.