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The refractive indices of human and rabbit meibomian secretions, and of several natural lipid mixtures and eye ointments, have been measured as a function of temperature and wavelength. A value of 1.482 was found for meibomian oil at typical eye surface temperature, but varies in humans between ca. 1.46 and 1.53 over the visible spectrum.
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John M. Tiffany (1986) studied this question.
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