April 2011
Volume 52, Issue 14
ARVO Annual Meeting Abstract  |   April 2011
Amphiphilic Lipids Of Human Meibum: Which, How Much, And What For?
Author Affiliations & Notes
  • Igor A. Butovich
    Department of Ophthalmology and Graduate School of Biomedical Sciences, University of Texas Southwestern Medical Center, Dallas, Texas
  • Footnotes
    Commercial Relationships  Igor A. Butovich, None
  • Footnotes
    Support  NIH Grant R01EY019480 and an unrestricted grant from Research to Prevent Blindness, New York, NY
Investigative Ophthalmology & Visual Science April 2011, Vol.52, 3743. doi:
  • Views
  • Share
  • Tools
    • Alerts
      This feature is available to authenticated users only.
      Sign In or Create an Account ×
    • Get Citation

      Igor A. Butovich; Amphiphilic Lipids Of Human Meibum: Which, How Much, And What For?. Invest. Ophthalmol. Vis. Sci. 2011;52(14):3743.

      Download citation file:

      © ARVO (1962-2015); The Authors (2016-present)

  • Supplements

Purpose: : Polar lipids (or, more correctly, amphiphilic lipids, AL) are considered to be critical components of the human tear film (TF). They are thought to be a part of the TF lipid layer (TFLL) that separates the underlying aqueous layer of TF from the top lipid layer formed from nonpolar lipids that comprise the bulk of human meibomian gland secretions (MGS). The goal of this presentation is to discuss the newest information on the presence and nature of the major AL classes in MGS, and assess their effects on TFLL.

Methods: : In this report, we will provide a detailed description of the major analytical techniques used in the presenter’s laboratory (emphasizing the role of modern chromatographic and mass spectrometric techniques), and those implemented in independent laboratories, to study MGS and TFLL. The strengths and weaknesses of current, and previously used, experimental techniques will be discussed.

Results: : The only major AL class detected in normal MGS was found to be extremely long chain (O-acyl)-omega-hydroxy fatty acids (OAHFA) of the Ck:l-C(O)O-Cm:n-COOH family (k=15 and 17; l=1 and 2; m = 29, 31, 33; n=0, 1, 2; only major isomers shown). OAHFA comprised more than 90% of all detected AL. These anionogenic compounds were consistently present in all tested MGS samples. Their molecular pattern was shown to be fairly reproducible from sample to sample. Other types of AL were also observed in MGS. Free fatty acids (FFA) of C15:1-COOH to C31:n-COOH (where n=0, 1, 2) were found in MGS, but their quantities (<0.1% of MGS, w/w) were two orders of magnitude lower than those reported earlier. The FFA pool closely resembled the FA content of cholesteryl esters of MGS. Only trace amounts of various ceramides (Cer), phospholipids (PL) and sphingomyelins (SM) were observed. The overall presence of these AL in MGS was less than 0.01% (w/w) each. Traces of FA amides observed in some samples were confirmed to be contaminations originated from organic solvents and lab ware. Cholesterol (Chl) was typically present in amounts not exceeding 0.7% of MGS. The effects of selected exogenously added AL on TFLL were evaluated in Langmuir trough experiments in vitro. A computational approach was developed to analyze the dynamic compression isotherms quantitatively. We found that these AL could negatively impact lipid layers formed from MGS through various mechanisms, but only if present in concentrations considerably exceeding normal ones.

Conclusions: : While AL are apparently needed for TFLL stabilization, certain AL could exert damaging effects on its stability. A revised model of the TFLL that includes OAHFA as major AL is proposed.

Keywords: protective mechanisms • lipids • cornea: tears/tear film/dry eye 

This PDF is available to Subscribers Only

Sign in or purchase a subscription to access this content. ×

You must be signed into an individual account to use this feature.