PURPOSE: The tear film lipid layer is believed to stabilize the tear film and to retard evaporation. Based on previous simple in vitro studies, the evidence for the latter property is scarce. In this study, we used complex lipid mixtures including various wax esters to study their physical properties and evaporation retarding effect. METHODS: Twelve samples of artificial tear film lipid layer mixtures composed of (L-α)-phosphatidylcholine, cholesterol oleate, and triglycerides were mixed with wax esters. A Langmuir balance was used to analyze the compressibility and rheological properties of these mixtures. In addition, a custom-built system was used for the evaporation studies used at 35°C. Lipid films were imaged with Brewster angle microscopy. RESULTS: None of the studied lipid mixtures decreased the evaporation rate. All lipid mixtures had similar compression isotherms and viscoelastic properties regardless of the wax ester species or its concentration. The results suggest that the overall properties of these mixtures are independent of individual lipid species and that these films are very cooperative and showed minor variation depending on the wax ester species. Brewster angle microscopy images revealed that the lipid films assembled into multiple layers. CONCLUSIONS: Wax ester-containing lipid mixtures resembling the tear film lipid layer are organized in a layered fashion so that amphiphilic lipids are adjacent to the aqueous phase and the nonpolar lipids are layered on top of these. This organization does not retard evaporation and raises overall questions about the role of lipids in the tear film. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.
PURPOSE: The tear film lipid layer is believed to stabilize the tear film and to retard evaporation. Based on previous simple in vitro studies, the evidence for the latter property is scarce. In this study, we used complex lipid mixtures including various wax esters to study their physical properties and evaporation retarding effect. METHODS: Twelve samples of artificial tear film lipid layer mixtures composed of (L-α)-phosphatidylcholine, cholesterol oleate, and triglycerides were mixed with wax esters. A Langmuir balance was used to analyze the compressibility and rheological properties of these mixtures. In addition, a custom-built system was used for the evaporation studies used at 35°C. Lipid films were imaged with Brewster angle microscopy. RESULTS: None of the studied lipid mixtures decreased the evaporation rate. All lipid mixtures had similar compression isotherms and viscoelastic properties regardless of the wax ester species or its concentration. The results suggest that the overall properties of these mixtures are independent of individual lipid species and that these films are very cooperative and showed minor variation depending on the wax ester species. Brewster angle microscopy images revealed that the lipid films assembled into multiple layers. CONCLUSIONS:Wax ester-containing lipid mixtures resembling the tear film lipid layer are organized in a layered fashion so that amphiphilic lipids are adjacent to the aqueous phase and the nonpolar lipids are layered on top of these. This organization does not retard evaporation and raises overall questions about the role of lipids in the tear film. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.
Authors: Mark D P Willcox; Pablo Argüeso; Georgi A Georgiev; Juha M Holopainen; Gordon W Laurie; Tom J Millar; Eric B Papas; Jannick P Rolland; Tannin A Schmidt; Ulrike Stahl; Tatiana Suarez; Lakshman N Subbaraman; Omür Ö Uçakhan; Lyndon Jones Journal: Ocul Surf Date: 2017-07-20 Impact factor: 5.033
Authors: Raied Fagehi; Gamal A El-Hiti; Mushawwat H Alsubaie; Ali Abusharha; Mana A Alanazi; Ali M Masmali; Turki Almubrad Journal: Healthcare (Basel) Date: 2022-02-21
Authors: Safal Khanal; Yuqiang Bai; William Ngo; Kelly K Nichols; Landon Wilson; Stephen Barnes; Jason J Nichols Journal: Invest Ophthalmol Vis Sci Date: 2021-07-01 Impact factor: 4.799
Authors: Raied Fagehi; Abdulkareem B Al-Bishry; Mana A Alanazi; Ali Abusharha; Gamal A El-Hiti; Ali M Masmali Journal: Taiwan J Ophthalmol Date: 2020-12-17