Abstract
Purpose: :
Previous studies have shown that certain combinations of multipurpose solutions (MPS) and silicone hydrogel (SH) lenses can lead to a cytotoxic effect in vitro and some combinations have the potential to exhibit excessive corneal staining in vivo. This in vitro study was undertaken to understand the interaction between MPS, SH surface treatment, lens material and human corneal epithelial cells (HCEC).
Methods: :
Immortalized HCEC were cultured in a keratinocyte serum-free medium supplemented with growth factors. A monolayer of HCEC was seeded in a 24-well tissue culture treated polystyrene plate. MPS tested were ReNu MultiPlus (ReNu), OptiFree Express (OFX), SoloCare Aqua and Complete Moisture Plus. SH materials evaluated were lotrafilcon A, lotrafilcon B, comfilcon A, galyfilcon A and balafilcon A (BA). MPS-soaked lenses were placed on top of adherent cells. Cell viability, adhesion phenotype and caspase activation were studied after 24-hr cell exposure.
Results: :
Except for BA, all other lenses soaked in OFX resulted in a significant amount of cells staining positive for caspases (p < 0.05). The viability and caspase results demonstrated that lens type had a significant effect on viability and interactive effect with MPS (p < 0.03). Significant reduction in the viability of cells exposed to materials soaked in OFX was also observed.With ReNu and OFX, a concentration-dependent effect on viability was demonstrated (p < 0.03). Regression analysis estimated that lotrafilcon A-OFX, which demonstrated decreased viability and increased apoptotic markers, had an effect equivalent to a 16% dilution of OFX. For all other materials, regression analysis estimated an effect equivalent to a dilution of OFX between 5-10%. These estimated "equivalent release" amounts correlated with the integrin expression and caspase activation results.
Conclusions: :
The results indicate that OFX-induced cell death may be influenced by the surface treatment of SH materials. It is speculated that the specific surface treatment of BA may allow MPS to be sorbed tightly to the lens, resulting in a significant reduction in MPS release. These findings suggest the necessity for the use of contact lenses in MPS biocompatibility testing, as different contact lens-MPS combinations can yield different effects on cells.
Keywords: contact lens • cell survival • cell adhesions/cell junctions