Bacterial blepharitis is a common inflammation of the eyelids caused by toxins from skin bacteria.  It is the most common cause of chronic infection of the external eye.  The bacteria typically infect the oil producing glands inside the eyelids.  Symptoms may include dryness, burning, gritty feeling, and itching of the eyelid margins.  Common signs may include crusting deposits on the eyelid margin and eyelashes, redness of the eyelid margins and loss of eyelashes.
Bacterial blepharitis tends to be chronic in nature and typically requires ongoing treatment including eyelid hygiene, topical medications, and in advanced cases, sometimes oral tetracycline.