FOLDING PROCEDURE FOR ACRYLIC INTRAOCULAR LENSES.

Purpose: To compare in vitro the effect of 2 standard methods of folding acrylic intraocular lenses (IOLs) on surface characteristics and bacterial adhesion. Setting: Eye Clinic and Department of Health—Microbiology Unit, University of Florence, Florence, Italy. Methods: To evaluate the effect of folding, 2 types of acrylic IOLs were not folded or folded with a forceps or an injector and then processed for scanning electron microscopy (SEM) examination. Bacterial adhesion was assessed using an ocular isolate of Pseudomonas aeruginosa. Nonfolded and folded IOLs were placed in test tubes containing the bacterial suspension for direct counting of viable adherent bacteria and for SEM. Results: The injector-folded IOLs did not show major alterations on the surface; 5 of the 9 forceps-folded IOLs showed marks or scratches in the profile of the optic. The mean number of viable adherent bacteria per area of IOL optic was 1082 (95% confidence interval [CI], 835-1330) in forceps-folded IOLs, 366 (95% CI, 192-359) in injector-folded IOLs, and 206 (95% CI, 123-289) in nonfolded IOLs. Scanning electron microscopy confirmed more surface irregularities on forcepsfolded IOLs, with bacteria adherent preferentially on the surface scratches. Conclusion: Forceps-folding provoked more surface irregularities, which probably make IOLs more susceptible to bacterial adhesion.