Influence of surgery-related factors on the Nd : YAG laser capsulotomy rates of 3-piece silicone IOLs - analysis of 457 pseudophakic human globes obtained post mortem

Background: The purpose of this study was to analyze any possible surgical reasons which may have had caused posterior capsule opacification in 3-piec e silicone IOLs that had required Nd:YAG laser treatment. Special attention was given to 1) quality of cortical clean up, 2) type of haptic fixation, and 3) continuous curvilinear capsulorhexis (CCC) size and shape. Materials and Methods: Human eyes obtained post-mortem implanted with 3-pie ce silicone optic- PMMA haptic (SI 40 NB) and 3-piece silicone optic - Prol ene haptic (SI 30 NB) designs IOLs, accessioned between January 1993 and De cember 2000 were evaluated by gross examination from behind under an operat ing microscope using the Miyake-Apple posterior photographic technique. The area and intensity of Soemmerring's ring and type of fixation was studied in 457 eyes. The mean diameter of the CCC and relation of the CCC edge to t he optic rim were analyzed in 221 eyes. Results: 1) The amount of Soemmerring's ring formation was significantly la rger in the group of IOLs requiring Nd:YAG capsulotomy in both the SI 40 NB and SI 30 NB design than in the IOLs without capsulotomies. 2) The percent age of not in-the-bag fixated IOLs in both the SI 40 NB and SI 30 NB design was larger in the "Nd:YAG groups", without being statistically significant . 3) The "Nd:YAG groups" showed a significant higher amount of non overlapp ing clock hours of the CCC edge in relation to the optic rim. Conclusion: 1) The data confirm the clinical assumption that the incidence of PCO is correlated with the cortical clean up. 2) Our findings also suppo rt the clinical assumption, that poor IOL fixation increases the risk of PC O. 3) This study also verifies the relation of the CCC to PCO, namely a rel atively small CCC covering the entire optic rim is best to reduce the Nd:YA G laser rate.