A Dr. Gary Hirshfield, MD, Ophthalmology, answered on behalf of American Academy of Ophthalmology's EyeSmart. Tearing is a very common complaint and is often difficult to solve because there are so many different causes. Any type of ocular surface irritation can cause tearing such as blepharitis, allergy or even dry eyes. Eyelid laxity and/or other malposition of the eyelid resulting from age or other causes such as Bell's palsy is another cause. Tear duct obstruction is another common cause and this can be diagnosed by an in office test. In some cases, special radiographic tests, such as dacrycstography, are used to follow the flow of tears through the system and to determine if there is functional blockage.