US EPA

3001646 

Journal Article 

Ex vivo analysis of cholesterol deposition for commercially available silicone hydrogel contact lenses using a fluorometric enzymatic assay 

Nash, WL; Gabriel, MM 

2014 

1 

Eye & Contact Lens
ISSN: 1542-2321
EISSN: 1542-233X 

40 

5 

277-282 

English 

25099866 

10.1097/ICL.0000000000000052 

WOS:000341983100002 

OBJECTIVE: Lipid deposition on silicone hydrogel (SiHy) lenses, which are believed to be caused by their hydrophobic surface, can lead to discomfort, reduced vision, and inflammatory reactions. This study used a highly specific and sensitive fluorometric enzymatic assay for ex vivo cholesterol analysis of seven types of SiHy lenses: balafilcon A, comfilcon A, enfilcon A, enhanced-lotrafilcon A, enhanced-lotrafilcon B, galyfilcon A, and senofilcon A.

METHODS: Cholesterol sorption was assessed in 140 previously worn SiHy lenses from 8 clinical trials conducted in the United States and Australia between 2006 and 2008. Patients wore the lenses for 2 to 4 weeks. Unworn negative control lenses for each lens material were obtained directly from the manufacturer. Lipids were isolated from the lenses using a two-step chloroform: methanol extraction method, and total cholesterol was quantified using a fluorometric enzymatic assay. Nonparametric Mann Whitney statistical analysis was performed to determine the differences in total cholesterol sorption between lens-specific data sets.

RESULTS: Enhanced-lotrafilcon A and enhanced-lotrafilcon B contact lenses showed significantly lower median total cholesterol sorption (median±quartile, 0.30±0.2 μg/lens and 0.09±0.1 μg/lens, respectively) than all other types of lenses that were tested (P<0.0001). By contrast, enfilcon A (3.96±0.8 μg/lens) and galyfilcon A (3.75±1.1 μg/lens) showed the highest median total cholesterol sorption of all tested lenses.

CONCLUSIONS: Cholesterol deposition in SiHy contact lenses seems to be lens polymer dependent. Enhanced-lotrafilcon A and enhanced-lotrafilcon B both sorbed the lowest amount of cholesterol compared with the other five types of SiHy lenses that were tested in this study.