Abstract
Purpose: :
Proteoglycan 4 (PRG4), a mucin-like glycoprotein, is present in the synovial joints and synovial fluid. PRG4 improves lubrication and contributes to the overall maintenance and integrity of the knee joint. PRG4 has recently been discovered at the ocular surface and as such may be useful in ocular applications as a lubricant. The purpose of this study was to incorporate PRG4 into model conventional hydrogel (CH) and silicone hydrogel (SH) contact lens materials and to determine the effect of PRG4 on surface characteristics and protein-sorption properties of these contact lenses.
Methods: :
One model CH (poly(2-hydroxyethyl methacrylate) [pHEMA]) and two model SH (pHEMA,Methacryloxypropyltris(trimethylsiloxy)silane [pHEMA TRIS] and N,N-Dimethylacrylamide, TRIS [DMAA TRIS]) lens materials were prepared with and without hyaluronic acid (HA) of molecular weight 35 or 132 kDa. PRG4 was isolated and purified from articular cartilage disks harvested from mature bovine stifle joints. PRG4 was incorporated into these materials at two different concentrations (1% and 5% by weight). Advancing water contact angle (CA), equilibrium water content, optical transparency (OT) and lysozyme sorption on these lens materials were investigated.
Results: :
Presence of PRG4 significantly decreased the CAs of both the HA and non-HA containing materials (p<0.05). Materials with higher concentration of PRG4 (5% wt) showed lower CAs than those with lower concentration (1% wt) (p<0.05). Incorporation of PRG4 did not have an effect on the OT when compared to the control. While there was no significant difference between PRG4 containing and non-PRG4 containing pHEMA-based materials (p>0.05), PRG4 containing SH materials showed a significant reduction in lysozyme sorption when compared to non-PRG containing SH materials (p<0.05). All the HA containing materials showed significantly lower CAs and reduced lysozyme sorption than non-HA containing materials (p<0.05).
Conclusions: :
Incorporation of PRG4 improves the hydrophilicity and reduces protein sorption without affecting the OT in model SH contact lenses. SH materials that contain PRG4 and HA have tremendous potential as hydrophilic, protein-resistant contact lens materials.
Keywords: contact lens • cornea: tears/tear film/dry eye