Tear lipocalin captures exogenous lipid from abnormal corneal surfaces

Area of Science:

• Ophthalmology
• Corneal Science
• Tear Film Dynamics

Background:

• The cornea's apical mucin layer and tears protect the ocular surface.
• Pathologic conditions disrupt this barrier, increasing meibomian lipid adhesion and creating unwettable surfaces.

Purpose of the Study:

• To investigate how pathologic ocular surfaces affect lipid binding to the cornea.
• To determine the role of tear proteins in removing adhered lipids from compromised corneas.

Main Methods:

• Studied lipid adhesion and removal on corneas with pathologic surfaces.
• Assessed fluorescence-labeled phospholipid capture by human tears using fluorometry.
• Separated tear proteins via gel filtration chromatography to identify lipid-binding components.

Main Results:

• Increased lipid adherence was observed on de-epithelialized corneas compared to intact corneas.
• Tear lipocalin was identified as the sole tear component binding the tested lipids.
• Lipid removal was significantly reduced in tears depleted of tear lipocalin and from Bowman's layer compared to epithelial surfaces.

Conclusions:

• Tear lipocalin effectively captures lipids from corneas affected by bullous keratopathy and dry eye.
• Enhanced lipid adhesion to Bowman's layer slightly hinders lipid removal.
• Reduced tear lipocalin secretion in dry eye disease may compromise lipid removal, potentially exacerbating ocular surface pathology.