Abstract
Purpose :
To determine the concentration of adsorbed proteins on the surface and the total protein of hydrogel and silicone hydrogel contact lenses.
Methods :
Four types of silicone hydrogel materials (lotrafilcon A, balafilcon A, senofilcon A, comfilcon A) and one type of conventional hydrogel (etafilcon A) were incubated in lactoferrin, lysozyme, IgA, albumin solutions (2, 2, 1, 0.1 mg/mL respectively) at 37 degree Celsius for 8 hours. Protein solutions were prepared in phosphate-buffered saline at a pH similar to that of human tears. A mixture of water, acetonitrile and trifluoroacetic acid was used to extract the total protein that was absorbed to lenses. Sequencing grade immobilized trypsin was used to digest and release only proteins absorbed to the surface of contact lenses. The concentration of desorbed proteins was measured by selected reaction monitoring mass spectrometry.
Results :
The highest and the lowest concentrations of total lysozyme were extracted from etafilcon A and senofilcon A (mean ± SD, 1.687 ± 0.356 vs 0.115 ± 0.137 µg/lens; p = 0.008). The highest and the lowest concentrations of total lactoferrin were extracted from balafilcon A and comfilcon A (0.763 ± 0.486 vs 0.155 ± 0.133 µg/lens; p = 0.017). The total amount of total IgA and albumin extracted from all lenses were the same (p > 0.05). The concentration of surface IgA extracted from senofilcon A (0.013 ± 0.030 µg/lens) was less than from lotrafilcon A (0.132 ± 0.283 µg/lens; p = 0.05). When etafilcon A, comfilcon A and balafilcon A contact lenses were soaked in the protein mixture, the concentration of total lactoferrin extracted was lower compared to when soaked in lactoferrin alone (etafilcon A, 0.049 ± 0.045 vs 1.318 ± 0.358, p < 0.001; comfilcon A, 0.070 ± 0.043 vs 0.240 ± 0.142, p = 0.005 and balafilcon A, 0.357 ± 0.066 vs 1.168 ± 0.331 µg/lens, p = 0.032). The concentration of surface lysozyme extracted from balafilcon A (0.889 ± 0.763) was different to lotrafilcon A (0.022 ± 0.037), comfilcon A (0.104 ± 0.317 µg/lens) and senofilcon (0.153 ± 0.340 µg/lens) (p <0.001). No other differences were found.
Conclusions :
The results of this study showed differences between the level of total proteins extracted from different lens types. The level of IgA and lysozyme extracted from the surface of contact lens polymers were also different. Lactoferrin deposition on tested contact lenses may be influenced by interactions between the molecules in the protein mixture.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.