In this video of the eye, you can see the punctum of the eyelid, where tears drain from the eye. The lacrimal system allows excess tears to drain from the eye into the nose … thus explaining why you get a runny nose when your eyes water.
There are a total of four puncta, found in the medial corner of both the upper and lower lids. The lower system is probably the most important for drainage, and is the first place chosen for punctal plugs in cases of dry eye.
The normal punctal opening should be slightly turned inward, pressed against the ocular surface (i.e. in a position such that the liquid tears can get in). With cases of ectropion, the eyelid is everted outward such that the pore opening is out of the tear layer, sitting out in the air. This can lead to excess eye watering and epiphora.
Download this video
To download this video, right click on a link below and choose “Save Target As…”
punctumanatomy.wmv (4.2 meg, Windows video file)