Abstract
Abstract: :
Purpose. Recent studies have shown that phospholipids are the most important class of lipids in maintaining the tear film stability. We developed a simple and sensitive method for quantitating phospholipids in human tears. Methods. Thirty patients with marginal dry eye, 20 patients with moderate dry eye, and 22 normal subjects were enrolled in the study. All subjects gave informed consent for participation. Five microliters of unstimulated tear was collected with a micropipette from the inferior tear meniscus in one eye of all subjects. Lipids fraction was extracted from the sample by the method of Folch. Phosphate was liberated by enzymatic reaction of phospholipase C and alkaline phosphatase from phospholipids in the lipid fraction. Free phosphates were detected using Molybdate-Malachite reagent at 595 nm. Results. Phospholipids concentration in tears from normal controls was 379.0±97.8 mg/L (mean ± standard deviation). Phospholipids concentration in tears from patients with marginal dry eye, and moderate dry eye were 290.8±160.1, and 146.7±51.5 mg/L, respectively, both of which were lower than that of normal controls with a statistical significance. Conclusions. This method enabled us to determine the amount of phospholipids from a small volume of tears. A deficiency of phospholipids, an important structural components in the polar phase of the tear film lipid layer, may be involved in the pathogenesis of dry eye syndrome.
Keywords: cornea: tears/tear film/dry eye • lipids • cornea: basic science