title: Quantification of human sebum on skin and human meibum on the eye lid margin using Sebutape®, spectroscopy and chemical analysis.
abstract: OBJECTIVE
  The purpose of this study was to determine if the variability in the amount of lid margin meibum is from donor-to-donor or from day-to-day variations and to determine if meibum from donors with meibomian gland dysfunction (MGD) had altered levels of casual eyelid meibum or skin sebum.
  
  
  METHODS
  Lipid absorbent Sebutape(®) was used to collect sebum or meibum. Samples were collected from six donors without dry eye and 21 donors with MGD. Lipid absorbed to Sebutape(®) was quantified using infrared and visible absorbance spectroscopy.
  
  
  RESULTS
  The amount of sebum from donors with MGD and donors without MGD was not significantly different. The amount of casual meibum from normal donors was 50% lower than that for donors with MGD using the spectroscopic assay, but was not significantly different using the chemical assay. The frequency and bandwidth of the infrared carbonyl band from sebum samples was significantly higher than that for meibum samples which indicates the carbonyls are in a different "dielectric" environment. The average relative standard deviation for the casual level of meibum and the level of sebum suggests that the 49% relative standard deviation of casual meibum measured once for each subject using a meibometer may have been due to day-to-day variations and not necessarily due to variations between individuals. The values measured using two different assays were correlated and therefore reliable.
  
  
  CONCLUSIONS
  The idea that tear film instability is associated with the quantity of lid margin lipid is not supported by this study because the quantity did not change with MGD. The amount of forehead sebum was not a bio-marker for MGD. Sebutape(®) is an excellent vehicle to remove tenths of a milligram of meibum from the eyelid and sebum from skin for experimental analysis.
authors: Department of Ophthalmology and Visual Sciences, University of Louisville, Louisville, Kentucky, USA.
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