Methods: 4 SH materials (balafilcon, galyfilcon, lotrafilcon A and lotrafilcon B) and 4 CH materials (polymacon, omafilcon, alphafilcon and etafilcon) were soaked in 125I-radiolabeled lysozyme. Following incubation, lenses were rinsed in PBS before soaking statically for 8 hours in lens cases containing 3ml of each care regimen: Alcon OptiFree® Express® (OFX), AMO Complete® Moisture Plus™ (COM), B&L ReNu® MoistureLoc™ (RML), B&L ReNu MultiPlus® (RMP), CIBA Aquify™ (AQ) and CIBA ClearCare® (CC). Following soaking, lens materials and regimens were measured for gamma radioactivity.

Results: Efficacy figures differed depending on the material-system combination. Etafilcon exhibited the greatest variation between care regimens, with OFX removing the most lysozyme (p<0.01), with an efficacy of 25% and AQ the lowest efficacy (5%). For the other CH materials, no significant difference was found between care regimens (p=NS): polymacon 35%, omafilcon 40% and alphafilcon 55% efficacy with all regimens. Cleaning efficacy with SH materials did not differ markedly between care regimens (p=NS), but did vary between SH materials: most materials had 5-20% efficacy, except galyfilcon, which had 30-50% efficacy (p<0.01). 

Conclusions:  Using a radiolabelled lysozyme technique, we were able to directly measure the amount of lysozyme remaining on lens materials after exposure to a variety of care regimens. For CH materials, etafilicon appears to be most influenced by care regimen composition. For SH materials, galyfilcon appears to be most easily cleaned of deposited lysozyme, possibly due to a more hydrophilic lens surface, resulting in reduced levels of denatured protein.