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Rahul Bhola, Morgan Hunter, Marta Yappert, Douglas Borchman, Dylan Gerlach; The Influence of Eyeliner Cosmetics and Squalene on the Conformation of Human Meibum. Invest. Ophthalmol. Vis. Sci. 2014;55(13):42.
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© ARVO (1962-2015); The Authors (2016-present)
Eye makeup and squalene (SQ), a natural component of eyelid sebum, could interact with human meibum; however, this possibility is yet to be tested. Aim of this pilot study was to measure makeup-human meibum interactions in vitro with the use of infrared spectroscopy.
Two popular brands of eyeliner makeup were studied: L’Oréal (Clichy, Hauts-de-Seine, France) Infallible pencil eyeliner and water-based Revlon (New York, NY. USA) ColorStay liquid eyeliner. Each eyeliner and SQ were mixed with human meibum pooled from three male and four female donors, with a median age of 21y (25% by weight). To quantify lipid phase transitions, the infrared CH2 symmetric stretching band near 2850 cm-1 was used to estimate temperature-dependent changes in the trans to gauche rotamer content of the lipid hydrocarbon chains.
The phase transitions for a pool of human meibum were reproducible and the phase transition parameters were similar to those obtained previously for normal human meibum. Both eyeliners exhibited phase transition temperatures that were much higher than those for meibum. The siloxane-containing pencil eyeliner increased the phase transition temperature by 4.2°C when combined with meibum. Because the lipid phase transition temperature of human meibum is near the physiological temperature of the surface of the eye, the small increase in phase transition temperature caused a large change, 30 to 49%, in the order, or stiffness, of the meibum-lipid hydrocarbon. The water-based liquid eyeliner caused no significant (p < 0.05) change in the phase transition parameters of human meibum. Squalene decreased the phase transition of human meibum by 5°C thus resulting in a large change in lipid order (30 to 24 %).
Modern cosmetics are highly regulated and relatively safe to use; however, it could be beneficial to design makeup products that do not interact with meibum, especially since women have a higher prevalence of dry eye symptoms. Infrared spectroscopy could be applied to the investigation of new products and their interactions with meibum. We propose that due to the fluid nature of SQ and the fluidizing effect of SQ on bulk meibum, SQ is likely to spread over the surface of the eyelid. Its loss in meibum from donors with meibomian gland dysfunction could contribute to the observed greater order (stiffness or viscosity) compared to that in meibum from donors without dry eye symptoms.
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