Summary: Blepharitis is one of the most common ocular conditions characterized by inflammation, scaling, reddening, and crusting of the eyelid. This condition may also cause burning, itching, or a grainy sensation when introducing foreign objects or substances to the eye. Although blepharitis is not sight-threatening, it can lead to permanent alterations of the eyelid margin. The overall etiology is a result of bacteria and inflammation from congested meibomian oil glands at the base of each eyelash. Other conditions may give rise to blepharitis, whether they be infectious or noninfectious, including, but not limited to, bacterial infections or allergies.
Reference Material:
https://en.wikipedia.org/wiki/Blepharitis