Changes in intraocular lens surface roughness during cataract surgery assessed by atomic force microscopy

PURPOSE: To analyze the changes in optic surface roughness before and after injection of various intraocular lens (IOL) models using atomic force microscopy (AFM). SETTINGS: Departments of Ophthalmology, Medical University of Graz, General Hospital Linz and University Hospital Basel; Upper Austria University, School of Applied Health and Social Sciences, Linz, Austria. DESIGN: Experimental study. METHODS: The morphology and surface roughness of 3 hydrophobic acrylic IOLs from different manufacturers were analyzed by AFM in liquid using the tapping mode. First, AFM was performed on IOLs taken from the original package without further manipulation. In a second step, under sterile conditions, an experienced cataract surgeon loaded the IOLs into the appropriate injection system and pushed them through a system resembling an IOL implantation in cataract surgery; this was followed by AFM evaluation. Finally, 3 samples of a preloaded hydrophilic acrylic IOL taken from the original cartridge were compared with 3 samples that were pushed through the implantation system. RESULTS: Comparison of the arithmetic mean, standard deviation, root mean square, and surface skewness of the IOLs before and after injection showed a significant increase in surface roughness (P<.05). CONCLUSIONS: Standard application procedures of IOLs may alter the IOL surface. Increases in the surface roughness of IOLs may influence postoperative posterior capsule opacification. Further studies are necessary to evaluate the interfacial properties of IOLs.