KINETIC DEPOSITION OF POLAR AND NON-POLAR LIPIDS ON SILICONE HYDROGEL CONTACT LENSES.

Purpose: This study investigated kinetic lipid uptake to four silicone hydrogel (SiHy) lenses over a period of four weeks, using an in-vitro radiolabel method.Methods: Four contemporary monthly replacement SiHy lenses (lotrafilcon B, senofilcon C, comfilcon A, samfilcon A) were incubated in three different solutions: 1) An artificial tear solution (ATS) containing (14)C-labeled phosphatidylcholine (PC), 2) an ATS containing (14)C-cholesteryl oleate (CO) and 3) an ATS containing four (14)C-radiolabeled lipids (PC, phosphatidylethanolamine, CO, and cholesterol (total lipid)). After 16 hours, lipids were extracted twice from the lenses with chloroform:methanol and the radioactive counts determined the lipid quantities to simulate 1 day of wear. OPTI-FREE PureMoist (Alcon) was used to clean and disinfect the remaining lenses daily and the lipid quantities were further determined after 2 weeks and 4 weeks.Results: The amount of total lipid increased for all lenses over time (p<0.01). After four weeks, total lipid accumulated was 20.26 +/- 0.15 microg/lens for senofilcon C, which was significantly higher (p<0.01) than all other lens materials (samfilcon A - 17.84+/-0.21; comfilcon A - 16.65 +/- 0.12; lotrafilcon B - 7.41 +/- 0.56 microg/lens). CO was highest on lotrafilcon B (1.26+/-0.13microg/lens) and senofilcon C attracted the most PC (3.95 +/- 0.12 microg/lens) compared to the other materials.Conclusion: The amount of both polar and non-polar lipid deposition on monthly replacement SiHy lenses increased over 4 weeks, with significant differences being seen between lens materials.