When considering common eye infections, several tissues may be affected:
- sclera - the white of the eyeball
- conjunctiva - the fine, colourless mucous membrane covering the front the sclera (bulbar conjunctiva) and the back of the eyelids (palpebral conjunctiva)
-  cornea - the pain-sensitive, clear tissue covering the iris and pupil.
-  eyelids and the margins where the eyelashes emerge Three main gland types produce tears making three layers:3,4,5,6
- meibomian glands on the underside of eyelids secrete an outer lipid layer which reduces evaporation
- lacrimal glands inside the upper eyelids secrete the aqueous middle layer containing nutrients and also anti-infective compounds
-  epithelial goblet cells in the cornea and conjunctiva along with acinar cells in the lacrimal glands secrete a mucin layer to help spread the tears and maintain eye wetness.

Tears drain from the eye via small ducts via the lacrimal puncta (a tiny opening on the eyelid rim) into the nasal passages.7