Lipid deposits on hydrophilic and rigid gas permeable contact lenses

Never-worn hydrophilic contact lenses (from each of the four FDA-classified groups) and rigid gas permeable (RGP) lenses were individually incubated for 24 hours at 37 degrees C with constant stirring in a mixture of 992 microL of 0.9% saline and 8 microL of a 1:1 chloroform:methanol solution of lipids (20 mg each of cholesterol, free fatty acid, triglyceride, fatty acid methyl ester, and cholesteryl ester, representative of lipids commonly found in the tear film). The lipid material deposited onto each lens was then extracted and its components separated using high performance thin layer chromatography. The chromatograms were analyzed by densitometry. Results indicate significant lipid deposition onto all lens types, with the siloxanyl alkyl acrylate RGP-type lenses accumulating two to three times as much total lipid as any of the other lenses. This suggests that hydrophobic RGP lenses, which also have lipophilic character, are most prone to develop lipid deposits. Among the hydrophilic lenses, nonionic polymer matrices and higher water content tended to increase lipid deposition.