Human eyes have three types of glands.
(i) Lacrimal glands: It is located above and in front of the eyeball. Ashra (अभुद्थ) is secreted from this gland. Tears keep the eyes moist and sterile.
(ii) Harderian glands: It is located behind the eyeball at the base of the eye. The oily substance secreted by these glands lubricates the cornea and prevents evaporation of tears.
(iii) Meibomian glands: It is located in the corner of eyeball. The oily substance secreted by these glands lubricates the cornea and prevents evaporation of tears.