Purpose: As of December 31, 2000, the neodymium:yttrium-aluminum-garnet (Nd:YAG) laser posterior capsulotomy rate for the Alcon AcrySof intraocular lens (IOL) as measured in our database was 3.3%. This was the lowest of any IOL model used in the United States. Only 12 of 361 cases required treatment. We analyzed possible surgical reasons that may have been responsible for the posterior capsule opacification (PCO) in this small group. Special attention was given to the three surgical factors that we had previously identified as being important for PCO reduction: (1) quality of cortical clean up, (2) type of haptic fixation, and (3) continuous curvilinear capsulorhexis (CCC) size and shape.
Design: Comparative autopsy tissue analysis.
Participants: Three hundred sixty-one human eyes obtained postmortem with Alcon AcrySof IOLs, accessioned between January 1995 and December 2000 from Lions Eye Banks.
Methods: The eyes were evaluated by the Miyake-Apple posterior photographic technique.
Main outcome measures: The area and intensity of Soemmering's ring and type of fixation were studied in 361 eyes. The size and shape of the CCC and relation of the CCC edge to the IOL's optic rim were analyzed in 168 eyes.
Results: The amount of Soemmering's ring formation was significantly larger in the group of IOLs requiring Nd:YAG capsulotomy (Nd:YAG group). The not in-the-bag fixated IOLs required more Nd:YAG capsulotomies. Although the trend was clear, the number of specimens was not large enough to acquire statistical significance. The Nd:YAG group showed a highly significant difference compared with the No Nd:YAG group with regard to the amount of clock hours of the CCC edge on the optic rim's surface (P < 0.001). Mean CCC diameters were significantly larger in the Nd:YAG group (P < 0.05).
Conclusions: The amount of Soemmering's ring correlates with the quality of cortical clean up. Cells within the Soemmering's ring are the direct precursors of PCO. This study confirms our previous laboratory studies and the clinical assumption that the incidence of PCO and thus the need for Nd:YAG capsulotomy is correlated with the cortical clean up. A second clinical assumption, that poor IOL fixation increases the risk of PCO, is also strongly suggested in this study. This study also verifies the relation of the CCC to PCO and the Nd:YAG laser, namely that a relatively small CCC without tears is best to prevent this complication. Use of a high-quality IOL combined with diligent attention to these three surgical factors should lower further the incidence of PCO.