**1.1 Definition**

Tear Film and Ocular Surface Society (TFOS) Dry Eye Workshop (DEW) II amended the definition of dry eye into "Dry eye is a multifactorial disease of the ocular surface characterized by a loss of homeostasis of the tear film, and accompanied by ocular symptoms, in which tear film instability and hyperosmolarity, ocular surface inflammation and damage, and neurosensory abnormalities play etiological roles" [1]. So, basically patients are not required to present with a particular set of symptoms to be diagnosed as dry eye disease (DED) but rather homeostasis of the tear film is more emphasized upon.
