what causes eyes to tear up
Tears are a combination of water, oil, and mucus. Healthy eyes glisten due to the presence of a balanced tear film. Excess water production in tears can be protective to the eye. Watery eye is usually caused by irritation or infection of the eye, injury to the eye from trauma, or a common cold. Other symptoms of eye irritation, including itching, redness, a gritty feeling, and swelling of the eyelids, often accompany watery eyes.