<unk> s (also called tarsal glands, palpebral glands, and tarsoconjunctival glands) are sebaceous glands along the rims of the eyelid inside the tarsal plate. They produce meibum, an oily substance that prevents evaporation of the eye's tear film. Meibum prevents tears from spilling onto the cheek, traps them between the oiled edge and the eyeball, and makes the closed lids airtight. There are about 25 such glands on the upper eyelid, and 20 on the lower eyelid. Dysfunctional<unk> s is believed to be the most often cause of dry eyes. They are also the cause of posterior blepharitis.
Meibomian gland
Serous gland
Areolar gland
Callus
Skene's gland
Subfornical organ
Ciaccio's glands
Cryptocotyle