Abstract
Purpose: :
To determine the lysozyme deposition profile of conventional and silicone hydrogel (SH) contact lens materials using confocal microscopy.
Methods: :
Acuvue 2 (etafilcon; AV2), Focus Monthly (vifilcon; FM), PureVision (balafilcon; PV), Acuvue Advance (galyfilcon; AA), Focus Night & Day (lotrafilcon A; FND) and O2Optix (lotrafilcon B; OPX) lens materials were incubated, in vitro, in a lysozyme–FITC (fluorescein–5–isothiocyanate) conjugate (1.0 mg/ml) in phosphate–buffered saline (PBS), for 4 weeks at 37°C with gentle rotation. The lysozyme–FITC conjugate was synthesized in–house by amine reaction. Free FITC was removed by Sephadex G25 and dialysis in PBS. The center 4 mm of the lenses was mounted on a microscope slide and scanned with a confocal microscope at 1 µm intervals, up to a depth of 100 µm. Mean fluorescence intensity was plotted as a function of the depth. Rhodamine–labeled dextran conjugates (molecular weight 2,000,000) in PBS was used to distinguish the lens surface.
Results: :
Lysozyme penetrated the entire depth of AV2, FM and PV materials. No lysozyme penetration was evident in the surface–treated (FND and OPX) SH materials. The penetration curve for AA was unique, with a partial penetration profile being observed even after 4 weeks.
Conclusions: :
Using a fluorophore–labeled protein with confocal microscopy allows for visualization of the location of proteins on and within a hydrogel material and shows much promise for studying the interaction of proteins with hydrogels made with various bulk and surface properties. Our results indicate that lysozyme penetration is significantly different between commercially available contact lens materials.
Keywords: contact lens • microscopy: confocal/tunneling • depth