The puncta are the 4 little holes, one in each top eyelid and one in each bottom eyelid that naturally drains our tears to ensure that we always have a fresh flow of tears to our eyes, and that old tears carry away any debris or allergens away. We can temporarily block them after we put our eyedrops in to ensure that our eyes are actually absorbing the medicated eye drops instead of them simply draining away before our eyes get a chance to use the prescribed medication. You can checkout Wikipedia for a bit more info.

Punctal occlusion is sometimes done for patients with dry eye, where tiny little punctal plugs can be inserted to retain the tears in the eyes by preventing them from draining as per normal. The general consensus in the dry eye sphere is that these more than often cause more irritation as it ends up causing more irritation of the eyes because fresh tears are no longer flushing out irritants from the surface of the eyes. You can read more about dry eye disease here.

However, there is a small population of dry eye patients where these punctal plugs offer significant relief. Book an appointment to have your dry eye assessed to see whether you're a candidate. It's often helpful to do a trial first with a temporary type of punctal plug.