Optometry Research Today is a free monthly online journal that collates and summarizes the latest research about Optometry, including details on myopia, optometric practice, therapy. | ||||||||
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Surface AFM microscopy of unworn and worn samples of silicone hydrogel contact lenses.González-Méijome JM, López-Alemany A, Almeida JB, Parafita MA Department of Physics (Optometry), School of Sciences, University of Minho, Braga, Portugal. PURPOSE.: To evaluate the qualitative and quantitative topographic changes in the surface of worn contact lenses (CLs) of different materials using atomic force microscopy (AFM). METHODS.: The topography of five different CL materials was evaluated with AFM over a surface of 25 mum(2) according to previously published experimental setup. Average roughness (R(a)) and root mean square (Rms) values were obtained for unworn and worn samples. RESULTS.: The R(a) value increased for balafilcon A (11.62-13.68 nm for unworn and worn samples, respectively), lotrafilcon A (3.67-15.01 nm for unworn and worn samples, respectively), lotrafilcon B (4.08-8.42 nm for unworn and worn samples, respectively), galyfilcon A (2.81-14.6 nm for unworn and worn samples, respectively), and comfilcon A (2.87-4.63 nm for unworn and worn samples, respectively). Differences were statistically significant for all lenses except Rms and R(a) for comfilcon A, and R(a) parameter for balafilcon A (p > 0.05). The least relative increase was observed for some balafilcon A samples and for some of these samples the roughness decreased after the lenses had been worn. CONCLUSION.: The changes in surface roughness between unworn and worn lenses are different for different silicone-hydrogel materials. Overall all CLs increased the degree of surface roughness after being worn, even for very short periods of time. However, for samples of balafilcon A, roughness increases at a lower extent or even can decrease as compared to unworn samples of the same material due to filling of the macropores. (c) 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008. Published 11 July 2008 in J Biomed Mater Res B Appl Biomater.
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