The Meibomian puzzle: combining pieces together

Area of Science:

• Ophthalmology
• Biochemistry
• Analytical Chemistry

Background:

• Human meibum and tear film contain complex lipid mixtures whose structures have been difficult to determine.
• Traditional lipid analysis methods required hydrolysis, hindering the reconstruction of intact lipid molecules, termed 'The Meibomian Puzzle'.

Purpose of the Study:

• To review and evaluate lipidomic analysis techniques for human meibum and tear film.
• To critically assess past and present analytical procedures and their results.
• To identify key lipid components and their role in tear film stability.

Main Methods:

• Review of existing literature on lipidomic analysis of meibum and tear film.
• Comparison of modern techniques (HPLC-MS) with older methods (NMR, GC, TLC).
• Critical evaluation of analytical procedures and obtained results.

Main Results:

• Modern techniques like High-Performance Liquid Chromatography-Mass Spectrometry (HPLC-MS) enable analysis of intact lipid molecules.
• Traditional methods had limitations, and some previous findings require re-evaluation.
• Meibum lacks typical phospholipids; instead, very long chain (O-acyl)-omega-hydroxy fatty acids are identified as potential tear film stabilizers.

Conclusions:

• Advanced lipidomic analysis is crucial for understanding meibum and tear film composition.
• Very long chain (O-acyl)-omega-hydroxy fatty acids are implicated in tear film stability and dry eye pathogenesis.
• These findings offer new targets for ocular surface and dry eye research.