Background: Our aim was to investigate the impact of manufacturing method andudmaterial composition on the surface characteristics of hydrogel contact lenses.udMethods: Five lens types were examined; three polyhydroxyethyl methacrylate (pHEMA)udlenses, each manufactured by a different technique, namely, lathing, spin-casting andudcast-moulding, a HEMA/methacrylic acid cast-moulded lens and a HEMA/glyceroludmethacrylate cast-moulded lens. Six lenses of each type were examined (front and back)udusing scanning electron microscopy (SEM). Additionally, both surfaces of three lensesudfrom each of the pHEMA lens groups were examined, partially hydrated, using an atomicudforce microscope (AFM). Qualitative data were gathered for both SEM and AFM studiesudin addition to root-mean-square (RMS) roughness values for the lenses investigatedudwith AFM.udResults: The surfaces of the lathed lenses were covered in lathing/polishing marks. RMSudroughness values for the anterior surface (10.9 ± 4.3 nm) were significantly greaterud(p = 0.02) than those of the posterior surface (9.3 ± 0.8 nm). The two surfaces of theudspun-cast lens appeared similar by SEM but AFM RMS roughness values were greaterud(p = 0.02) for the anterior (12.3 ± 1.8 nm) than the posterior (5.8 ± 1.9 nm) surface. BothudSEM and AFM showed similar topographic appearances for the surfaces of the cast-mouldedudpHEMA lens, although RMS roughness values were greater (p = 0.02) for the anteriorud(5.8 ± 0.9 nm) than the posterior (3.9 ± 0.3 nm) surface. All three cast-moulded lensesudhad more processing debris than the lathed and spun-cast pHEMA lenses. Overall, theudsurfaces of the lathed lens were 'rougher' than those of the cast-moulded lens (p = 0.01).udConclusion: The surface topographies of the hydrogel contact lenses are dependent onudthe method of manufacture. Cast-moulded lenses are associated with apparently 'stickier'udsurfaces, which may be indicative of surface degradation during the manufacturingudprocess.
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