Lysozyme and lipid deposition on silicone hydrogel contact lens materials.
OBJECTIVE
We sought to determine whether there were differences in lysozyme (quantity and conformation) and lipid deposition on in vivo worn conventional (etafilcon) and silicone hydrogel (balafilcon and lotrafilcon) contact lenses.


METHODS
After extraction, lysozyme concentration in each extract was determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting. Lysozyme activity was determined by the rate of lysis of Micrococcis lysodeikticus cells. Lipid deposition was determined by high-performance liquid chromatography.


RESULTS
Lysozyme deposition on etafilcon lenses was significantly greater than that measured on silicone hydrogel (SH) lenses (985 microg per lens versus 10 and 3 microg per lens for balafilcon and lotrafilcon materials, respectively; P<0.001). The degree to which lysozyme was denatured was influenced by the lens material, with the lowest degree of denaturation (22%) seen on the conventional lens material, as compared with 50% for balafilcon and 80% for lotrafilcon (P<0.001). Lipid deposition was greatest on the SH materials, with up to 600 microg per lens of certain lipid classes being deposited on balafilcon, as compared with 20 microg per lens on etafilcon (P<0.001).


CONCLUSIONS
The quantity and conformation of lysozyme and the quantity of lipid deposited on hydrogel contact lenses is significantly influenced by the composition of the lens material. SH contact lens materials deposit low levels of lysozyme and high levels of lipid deposition compared with ionic contact lens materials. Although SH materials deposit only small amounts of lysozyme, the degree of lysozyme denaturation that occurs is higher relative to that seen on ionic lens materials.
Jones
Lyndon
L
Centre for Contact Lens Research, School of Optometry, University of Waterloo, Waterloo, Canada. lwjones@uwaterloo.ca
Senchyna
Michelle
M
Glasier
Mary-Ann
MA
Schickler
Jillian
J
Forbes
Iain
I
Louie
Derek
D
May
Christopher
C
D001672:Biocompatible Materials; D002851:Chromatography, High Pressure Liquid; D003263:Contact Lenses, Hydrophilic; D006801:Humans; D050356:Lipid Metabolism; D008689:Methacrylates; D009113:Muramidase / Q000378:metabolism*; D011446:Prospective Studies; D012826:Silicone Elastomers
D001672:Biocompatible Materials; D008689:Methacrylates; D012826:Silicone Elastomers; C114176:etafilcon; D009113:Muramidase