Tear Film Constituents and Medicines for Eyes Investigated as Langmuir Films

Abstract

The tear film has an important role on the quality of the vision process and is of importance in the fields of ophthalmology and optometry. The lipid layer, the outermost part of the tear film, can be investigated with the Langmuir technique, as well as the interaction of components of the aqueous part of the tear film with those of the lipid layer. Dysfunctions in the stability and composition of the tear film are the causes of eye diseases, as the dry eye syndrome. For the treatment of this disease, the artificial tears are used, and one type of them are the lipid tears, which can be investigated with the Langmuir technique. This technique can also be used to investigate the influence on the lipid layer of other artificial tear components or medicines instilled in the eye. This review presents investigations where the Langmuir technique has been used in relation with the tear film. In particular, the surface properties of natural tears and of four commercial lipid-containing artificial tears have been reported and discussed in connection with their composition.