These are small glands that run along the edge of the upper and lower eyelid. Meibomian glands produce oil that is continuously excreted into the tear film. This oil keeps the tears slippery and also forms a protective “evaporation proof” barrier on the surface of the tear film. The meibomian gland pore openings are small, and can’t easily be seen without a microscope. If a meibomian gland pore gets clogged, the oil can back up into the eyelid and form a chalazion. Chalazions will sometimes spontaneously drain with the use of warm compresses and massage but will sometimes require surgical drainage in the office. Blepharitis is a condition where chronic eyelid irritation makes the eyes look puffy and feel sandy. Blepharitis also tends to clog the meibomian glands, which is why warm compresses and massage are often recommended for this condition as well … to keep the meibomian glands flowing properly.