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Jean T. Jacob, Jenae M. Guinn, Tamika Y. Edwards; Visualization of Lipid Penetration into Contact Lenses by Confocal Microscopy. Invest. Ophthalmol. Vis. Sci. 2011;52(14):6543.
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To investigate the ability of confocal microscopy to visualize the penetration of lipids into silicone hydrogel (SiHy) contact lenses and then to use confocal microscopy to determine the effects of varying lens material properties and surface treatments as well as two multipurpose cleaning solutions (MPS) on the extent of that lipid penetration over periods of simulated wear.
The degree of penetration and adsorption of fluorescently-labeled phosphatidylcholine (PC) and cholesterol (Chol) penetration into four types of SiHy lenses (Balafilcon, Lotrafilcon, Senofilcon, Comifilcon) after 30 mins, 1, 12, 24, or 36 hrs of simulated wear conditions was determined using confocal microscopy. The resulting cross-sectional images and mean fluorescent intensity data collected for each sample by using the software-based histogram utility was compared and contrasted. Penetration differences between the central 6 mm and the peripheral edges of the lenses were also analyzed. Additionally, the effects of two MPS on the degree of lipid penetration after exposure to 24 hours of labeled-artificial tear solution (ATF) were determined.
Confocal microscopy allows good spatial visualization of the lipid penetration into silicone hydrogel lenses. The penetration of both lipids into all lenses was generally diffusion dependent. However, tagged-PC showed more specific surface interaction with some of the lens surfaces (Balafilcon and Senofilcon) than tagged-Chol. The rate of the diffusion was dependent upon the lens surface and the initial lipid-surface interaction. Balafilcon and Senofilcon showed more punctuate surface lipid penetration then the other lens types. By 24 hrs of exposure to labeled-ATF, lipid was detectable throughout the bulk of all lens types. Differences between the rate of lipid penetration between the central and peripheral edges of the lenses were noted for all lenses by only significant for Balafilcon. The cleaning effects of both MPSs varied depending upon the lipid and lens type.
Fluorescently-labeled ATF components and subsequent confocal microscopy analysis are useful for determining differences in surface modification techniques and biofouling of SiHy lenses.
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