Patients with chronic blepharitis having significant meibomian gland involvement will be investigated to determine the associated type and frequency of generalized dermatologic abnormality, especially that which involves the sebaceous glands. Clinical evidence will be sought which might give insight into the mechanism for the production of the frequently encountered keratoconjunctivitis. Lipid assays will be carried out on the tear film lipids as well as lipids still in the meibomian glands in these patients and compared to lipids of normal controls in search of an explanation for the frequently observed unstable precorneal tear film. Aerobic and anaerobic bacteriological cultures will be done to evaluate the role of bacteria in this condition. Isolated bacteria will be maintained in culture and assayed for the production of a lipase which could produce changes in the tear lipids. Meibomian gland morphology will be compared by light and electron microscopy in normals and disease. Lid temperature will be determined by surface measurements and thermography to estimate the possible role of temperature variation in the disease process. Melting and spreading temperature of the tear lipids from normals and those with blepharitis will be compared. Various modes of therapy will be evaluated.