Demodex are a species of mite which is present on all humans.  Unfortunately sometimes these mites can get out of hand and infest the eyelashes and oil glands causing symptoms which are similar to dry eye.  One way to confirm the presence of demodex eyelid and eyelash infestation is by looking for "collarettes" at the base of the eyelashes.  Additionally, people with demodex infestation frequently lose lashes.  While it is impossible to completely eliminate demodex, it is possible to control them with eyelid cleaning and special medications.