|Title||MASS SPECTROMETRY METHOD DEVELOPMENT FOR ANALYSIS OF TEAR FILM LIPIDS ON SILICONE HYDROGEL CONTACT LENSES|
|Author, Co-Author||Corrie Ziegler, Kelly Nichols, Kari Green-Church|
|Abstract|| PURPOSE: Mass spectrometry is a powerful technique in the analysis of tear film lipids and proteins. It has been reported that silicone hydrogel contact lens materials attract tear film lipids. The purpose of this method development is twofold: (1) to assess lipids on the surface of silicone hydrogel contact lenses following wear by a subject, and (2) to evaluate the potential to use silicone hydrogel lenses as tear lipid collection devices.
METHODS: Four storage and extraction methods were tested including removal of contact lenses and storage in sterile saline, multi-purpose solution, 1:1 chloroform/methanol, and methanol (with subsequent addition of chloroform prior to analysis by electrospray time-of-flight mass spectrometry). All samples were directly infused at 20uL/min to a Micromass LCT mass spectrometer equipped with an orthogonal electrospray source (Z-spray).
RESULTS: Lipid spectra under each storage and extraction condition were compared to lipid spectra collected directly from meibomian gland secretions. The most successful technique involves removal and direct storage in methanol and the addition of chloroform prior to analysis. Viable spectra were also collected when the 1:1 chloroform/methanol solution was used to store the directly removed contact lens. Storage in saline or multipurpose solution followed by the addition of chloroform or higher volumes of chloroform/methanol resulted in disintegration of the lenses and visible polymer on the mass spectra. The spectra measured using the optimal extraction conditions was similar to meibum spectra; however fewer higher molecular weight species were present.
CONCLUSIONS: Silicone hydrogel lens materials may respond differently than other soft lens materials to chemicals needed to extract lipid from the lenses for mass spectrometry. Lens removal at the time of the examination and direct storage in extraction chemicals produces the highest quality spectra. Further work is needed to determine the level of lipid binding to silicone hydrogel contact lenses.
|Affiliation of Co-Authors||The Ohio State University, College of Optometry|