The role of multi-purpose solutions in prevention and removal of lipid depositions on contact lenses

• Five commercial contact lenses were placed in an artificial tear fluid to measure sorption of cholesterol and a phospholipid.
• Presoaking with commercial multi-purpose solutions was done in an attempt to block or reduce lipid sorption.
• Simulated cleaning with commercial multi-purpose solutions was done to remove sorbed lipids.
• Multi-purpose solutions had little effect in preventing lipid sorption.
• Multi-purpose solutions removed some sorbed lipids, depending on the solution and the lens type.

The sorption and desorption of radiolabeled dipalmitoylphosphatidylcholine (DPPC) and cholesterol (CH) were measured on 5 types of commercial contact lenses. The lenses were soaked in vitro in an artificial tear fluid for 16 h. The effects of borate buffered saline and two commercial multi-purpose lens-care solutions (MPSs) on reducing the lipid (DPPC and CH) sorption and increasing the lipid removal were examined. The results showed that silicone hydrogel (SiHy) lenses accumulated the most lipids, sorbing over an order of magnitude more than polymacon, a conventional hydrogel lens. Pre-soaking the SiHy lenses for 16 h in MPSs reduced the DPPC sorption by up to 13% and the CH sorption by up to 11%, compared to controls that were not pre-soaked. However neither these reductions nor those on polymacon were statistically significant (p > 0.05). In sorption experiments without presoaking, subsequent exposure to the MPSs removed some DPPC from the lenses (0–3.1% for SiHy lenses and 14–55% for polymacon), but CH removal was 0.0–0.8% for SiHy lenses and 0.6–28% for polymacon lenses. Some of these removals were statistically significant (p < 0.05).