To investigate the mechanism of protein and lipid adherence to hydrophilic contact lenses in vivo.
Two types of new, never-worn hydrophilic contact lenses (tefilcon and vifilcon) were simultaneously worn by eight experienced, asymptomatic contact lens wearers on 12 separate occasions. Deposited lipids were removed with a methanol based extraction procedure, separated using high performance thin layer chromatography, and quantitatively analyzed densitometrically. Deposited proteins were extracted with 4M urea, separated using gel electrophoresis and quantitatively analyzed densitometrically.
Four lipids and one protein were deposited in quantifiable amounts onto each worn lens. Lysozyme demonstrated material-dependent deposition whereas total lipid did not. Subject-dependent differences in the deposition of both lysozyme and total lipid were observed primarily on group IV lenses. The deposition of triolein, the largest lipid extracted, was found to be material- but not subject-dependent. The deposition of smaller lipids was found to be subject-but not material-dependent.
Significant amounts of both protein and lipid were extracted from both types of lenses after 1 day of wear. Lysozyme deposition was material-dependent because of its affinity for negative charges on group IV lenses. The abundance of binding sites on a group IV lens allows protein and lipid deposition to be subject-dependent after short periods of wear. Lipid deposition appears to be influenced by size. Collectively, the results suggest that subject-dependent variations in deposition are modulated by both material and contaminant characteristics.