[Quantification of capsular sack forces after intraocular lens implantation]

In order to quantify the force acting in the capsular bag following implantation of an intraocular lens (IOL), 58 J- and C-loop lenses obtained from four different manufactures were implanted into the capsular bag in porcine eyes. The cornea and iris were removed before implantation. Photographs of the capsular bag before and after implantation, with a measuring rod for comparison, were taken under a microscope. In this way, the compression of the haptics could be measured (mean 1.7 mm, standard deviation 0.6 mm). Afterwards one haptic of each lens was fixed in a special mount placed on a high precision scale and the opposite haptic was compressed by 2 mm using a special micrometer-screw. After 5 min compression time, differences of 300% between the different manufacturers and lens types were measured. To find out whether the differences measured have an influence on the deformation of the capsular bag, a graph was plotted with force measured and values for elongation of the capsular bag along the axes. In this way a correlation of the elongation and the force could be shown. The results show that besides shaping the haptics of IOLs, the force necessary to compress the haptics also has an influence on the final form of the capsular bag.