KERATOCONJUNCTIVITIS SICCA ASSOCIATED WITH MEIBOMIAN SECRETION POLAR LIPID ABNORMALITY

Objective: To determine whether an association between keratoconjuncti vitis sicca (KCS) and meibomian gland lipids exists in patients with c hronic blepharitis. Methods: Meibomian gland lipids were collected fro m normal patients and those with chronic blepharitis. Some of the chro nic blepharitis patients had an ocular surface abnormality with appare nt aqueous deficiency similar to KCS. Lipids were separated by thin-la yer chromatography and polar lipids were further separated by high-pre ssure liquid chromatography with detection by UV absorbance. Lipids we re identified by retention time with comparison with standards and by gas chromatography and mass spectroscopy. Results: A strong associatio n between specific lipids and KCS signs was observed only with the pol ar lipids. Low levels of 2 phospholipids, identified as phosphatidylet hanolamine and sphingomyelin, were significantly (P<.05) associated wi th ocular surface abnormalities that were consistent with KCS. Conclus ions: Evaporative KCS syndrome (rather than tear insufficiency) in man y individuals may be the result of polar lipid abnormalities. We belie ve that the 2 associated phospholipids identified in the patients with chronic blepharitis act as important structural components in the pol ar phase of the tear film lipid layer. We suggest that a deficiency in these lipids results in a poorly structured polar phase that in turn affects the nonpolar phase. Ultimately water transmission through the tear film lipid layer increases, thus resulting in evaporative KCS. Th ese results should aid in development of tear film substitutes directe d toward specific abnormalities.