Purpose. To examine the effect of cholesterol on the adhesion of bacteria to silicone hydrogel contact lenses.
Methods. Contact lenses, collected from subjects wearing Acuvue Oasys or PureVision lenses, were extracted in chloroform:methanol (1:1, v/v) and amount of cholesterol was estimated by thin-layer chromatography. Unworn lenses were soaked in cholesterol, and the numbers of Pseudomonas aeruginosa strains or Staphylococcus aureus strains that adhered to the lenses were measured. Cholesterol was tested for effects on bacterial growth by incubating bacteria in medium containing cholesterol.
Results. From ex vivo PureVision lenses, 3.4 ± 0.3 μg/lens cholesterol was recovered, and from Acuvue Oasys lenses, 2.4 ± 0.2 to 1.0 ± 0.1 μg/lens cholesterol was extracted. Cholesterol did not alter the total or viable adhesion of any strain of P. aeruginosa or S. aureus (p > 0.05). However, worn PureVision lenses reduced the numbers of viable cells of P. aeruginosa (5.8 ± 0.4 log units) compared with unworn lenses (6.4 ± 0.2 log units, p = 0.001). Similarly, there were fewer numbers of S. aureus 031 adherent to worn PureVision (3.05 ± 0.8 log units) compared with unworn PureVision (4.6 ± 0.3 log units, p = 0.0001). Worn Acuvue Oasys lenses did not affect bacterial adhesion. Cholesterol showed no effect on the growth of any test strain.
Conclusions. Although cholesterol has been shown to adsorb to contact lenses during wear, this lipid does not appear to modulate bacterial adhesion to a lens surface.
Brien Holden Vision Institute (NBO, HZ, ZZ, JO, BX, MDPW), School of Optometry and Vision Science, University of New South Wales (NBO, HZ, MDPW), Sydney, New South Wales, Australia, and Research, Alcon Labs, Fort Worth, Texas (RB).
This work was supported, in part, by a grant from Alcon Laboratories Inc., Ft. Worth, Texas.
This paper was presented at the 2010 Annual Meetings of the Association for Research in Vision and Ophthalmology in Fort Lauderdale, Florida and British Contact Lens Association in Birmingham, UK.
Received October 18, 2010; accepted March 10, 2011.
Negar Babaei Omali; Brien Holden Vision Institute; Level 5, North Wing, RMB, Gate 14, Barker Street; University of New South Wales; Sydney 2052, NSW; Australia; e-mail: email@example.com