The Use of Scanning Electron Microscopy to Evaluate the Effectiveness of Soft Contact Lens Care Solutions in Removing Proteins from Soft Contact Lenses

Objective: To evaluate the ability of scanning electron microscopy (SEM) and image computer statistical analysis (ICSA) to quantitatively assess the effectiveness of protein removal from soft contact lenses by soft contact lens care solutions. Methods: Soft contact lenses were soaked in artificial tears for 65 hours to simulate protein adsorption. Two contact lens care solutions and phosphate buffered saline (PBS) were then used separately to rub, rinse, and soak the lenses for 6 hours. After fixation with glutaraldehyde, the lenses were dried. The morphology and quantity of protein on the surface of the lenses were inspected by SEM and ICSA. The cleansing rate was expressed as a mass fraction, i.e., a percentage of before and after treatment with the care solution. Single factor analysis of variance was used to analyze the protein clearance rate of lens treated with different treatments by Tukey multiple comparison method. Results: The contact lens care solution had a significant cleaning effect on the surface protein of the lenses. For PBS and the two kinds of contact lens care solutions from different manufacturers, the protein clearance rates of the lenses were 89.58%, 98.18% and 98.38% at 100× magnification and 89.76%, 98.42% and 98.27% at 1 500× magnification. Conclusion: SEM combined with ICSA can effectively evaluate the protein cleaning efficacy of contact lens care solutions. Contact lens care solutions have a significant cleaning effect on the surface protein of the lenses. Key words: scanning electron microscopy; image computer statistical analysis; soft contact lens care solution; soft contact lenses; protein