There are four puncta, or drains through which tears leave the eyes. Two are located in the nasal corners of the upper eyelids, and two in the nasal corners of the lower eyelids.
Puncta are mostly of interest to the dry eye patient because closing them (some or all) is a popular treatment for dry eye. This can be done by placing tiny plugs in the puncta (openings) or all the way down in the canalicula. It can also be done by surgically sealing the puncta (cautery).