In vitro lipid deposition on hydrogel and silicone hydrogel contact lenses

To understand various soft contact lens materials' ability to adsorb common tear lipids.

Ten unworn polymers of nine types were individually soaked in 1.0 mL of 1.75 μg/mL cholesterol oleate or 1.0 mL of 0.5 μg/mL phosphatidylcholine solutions for 1 or 14 days. The adsorbed lipids were extracted with chloroform-methanol, which underwent assay quantification for cholesterol oleate and inorganic phosphate.

More phosphatidylcholine was extracted after 14 days than after 1 day in only lotrafilcon B, balafilcon A, and enfilcon A (all P < 0.005). After 1 day of incubation in phosphatidylcholine, 0.54 to 4.17 μg/lens phosphatidylcholine was recovered from the polymers, and after 14 days of incubation in phosphatidylcholine, 0.58 to 5.77 μg/lens phosphatidylcholine was recovered from the polymers. Etafilcon A had significantly more cholesterol oleate at 1 day than at 14 days, and lotrafilcon A, lotrafilcon B, and balafilcon A had significantly more cholesterol oleate at 14 days than at 1 day (P < 0.005). After 1 day of incubation in cholesterol oleate, 0.14 to 4.80 μg/lens cholesterol oleate was recovered from the polymers. After 14 days of incubation in cholesterol oleate, 1.40 to 6.84 μg/lens cholesterol oleate was recovered from the polymers.

Hydrogel and most silicone hydrogels appear to adsorb lipids relatively quickly (i.e., within the first day). Although there is some variability in the amounts recovered across materials, it is uncertain whether these differences have any clinical significance.