Classification of chronic blepharitis.

Since last thoroughly evaluated over three decades ago, the clinical spectrum of chronic blepharitis has changed. The relative prevalence of Staphylococcus aureus alone or in combination with seborrheic blepharitis has decreased. The relative prevalence has increased of seborrheic blepharitis with or without associated excess meibomian secretions (meibomian seborrhea) or inflammation (meibomitis). Primary meibomitis appears not to be a primarily infectious entity but to represent a facet of generalized sebaceous gland dysfunction and to be found in association with seborrheic dermatitis or acne rosacea. The keratoconjunctivitis found in association with primary meibomitis may be contributed to by the production of bacterial lypolytic exoenzymes that split neutral lipids, resulting in an increased level of free fatty acids in the tears. A frequent finding of keratoconjunctivitis sicca in this patient population, especially the S. aureus group (50%), is of note. Of particular importance is that these entities be recognized as chronic diseases requiring control and ones for which there is no "cure."