Borchman D, et al. - Given that insights into the loss of tear film stability may be afforded by the compositional, structural, and functional associations of meibum, and although the conformation of meibum lipids has been analyzed rigorously, that of tear lipids has not, therefore, researchers prospectively pooled tear lipids and meibum from patients who had hematopoietic stem cell transplantation, and retrospectively examined the infrared spectra of meibum from donors with and without meibomian gland dysfunction in order to measure the lipid composition and structure. They measured the relative content of CH₃ and CH₂ moieties in the meibum by using the infrared CH stretching region. They found that compared with meibum lipids, tear lipids were more ordered, and this could have functional results. The human meibum peak height ratio of the CH₃/CH₂ bands was not identified as a factor associated with tear film stability with age or gender. Findings are suggestive of a possible contribution of the amount of CH₃ moieties relative to CH₂ moieties and saturation to a higher meibum lipid order related to a younger age, meibomian gland dysfunction, and dry eye from hematopoietic stem cell transplantation. Hence, the possible role of hydrocarbon order as a marker of or contributor to an unstable tear film layer was suggested.