Abstract
Purpose :
Lehfilcon A is a new monthly replacement contact lens with a silicone hydrogel core and a Celligent® Technology water gradient surface with a ≥90% surface water content. The surface polymer, 2-methacryloyloxyethyl phosphorylcholine (MPC), creates a nanofiber structure on the lehfilcon A lens surface. MPC coatings protect against fouling by foreign substances, including microorganisms. Therefore, in this in vitro experimental study, we examined the ability of Serratia marcescens to adhere to lehfilcon A and leading monthly or bi-weekly replacement contact lenses.
Methods :
We performed quantitative adhesion assays to evaluate the adherence of S. marcescens to seven contact lens materials (lehfilcon A, comfilcon A, senofilcon A, omafilcon B, fanfilcon A, balafilcon A, and senofilcon C). Individual contact lenses were incubated in the presence of S. marcescens and gently rinsed to remove non-adherent bacteria. Adherent bacteria were eluted from lenses via sonication and bacterial colony forming units (CFU) were enumerated by plating. CFUs were normalized to the surface area of each lens. Statistical analyses were performed as t-tests for differences in the mean log CFU/mm2 between lens types without assuming equal standard deviation between groups. Bonferroni correction was used to account for multiple comparisons.
We performed fluorescent microscopy to qualitatively evaluate bacterial adherence to lehfilcon A and comparison lenses. The cell surface of live S. marcescens was stained with a protein-conjugating dye, 5(6)-Carboxytetramethylrhodamine succinimidyl ester (TAMRA-SE). Labeled bacteria were used in adhesion assays as described above, fixed with paraformaldehyde, and contact lenses were imaged using a TRITC filter.
Results :
We observed lower densities of S. marcescens adhered to lehfilcon A (2.6 ± 0.3 log CFU/mm2) relative to the next best performing lens material, comfilcon A (4.6 ± 0.3 log CFU/mm2; p < 0.0001). This difference corresponds to ≥99.0% lower adhesion to lehfilcon A. In agreement, fluorescent microscopy visually demonstrated lower levels of bound bacteria to lehfilcon A vs alternative lens materials.
Conclusions :
Our in vitro data suggests that S. marcescens adheres to lehfilcon A at low levels relative to comparable marketed contact lenses. These results add to the body of evidence that MPC coatings confer anti-fouling properties to medical devices.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.