Blepharitis is a flaky, crusty buildup from bacterial flora and demodex mites that leads to inflammation of the eyelid margin caused by exotoxins.  Untreated blepharitis leads to irritated, swollen, itchy, red eyelid margin and recurrent hordeola development. 

The inflamed lid margin from the exotoxins causes telangiectasia and lid hyper keratinization (thickened skin) leading to decrease in function of meibomian glands.  Meibomian glands are curial to help stabilize a healthy tear film and when compromised leads to evaporative dry eye.