Five‐year follow‐up of posterior capsule opacification with two different silicone intraocular lenses

Editor, Last year we presented a paper comparing posterior capsule opacification (PCO) rates between two different silicone intraocular lenses (IOLs), the SI 40NB (AMO Inc.; Santa Ana, CA, USA) and the CeeOn Edge (911 A; AMO Inc.) with a 3-year follow-up (Sundelin et al. 2005). In order to investigate whether the difference in PCO rates between the two IOLs was consistent over a longer period of time, a 5-year follow-up was performed. The material and methods used were exactly the same as in the previous study (Sundelin et al. 2005). Sixty patients of the original 116 were able to participate in the 5-year follow-up. One patient had been treated with Nd:YAG laser capsulotomy since the 3-year examination. Two patients underwent capsulotomy at the 5-year examination. A total of 12 of the 116 patients underwent capsulotomy during the 5-year follow-up, an incidence of 10%. All 12 had an SI40NB IOL and the difference between the two IOLs was statistically significant (p < 0.001, Fisher's exact test). The evaluation of posterior capsule opacification (EPCO) scores obtained at the 5-year examination were compared after subtraction of the baseline value taken at 2 months. There was no statistically significant difference between the IOLs (p = 0.224, Mann–Whitney U-test) (Fig. 1). However, in this analysis all patients who underwent capsulotomy during the 5-year follow-up period were excluded. When the last EPCO scores obtained before capsulotomy for these 12 patients were included in the analysis, a statistically significant difference arose between the two IOLs (p = 0.046, Mann–Whitney U-test), with less PCO occurring with the CeeOn Edge IOL (Fig. 2). Evaluation of posterior capsule opacification (EPCO) values for the two different intraocular lenses at 5 years postoperatively. The EPCO values at 2 months, regarded as baseline values, were subtracted from the values at 5 years. As there was spontaneous improvement in EPCO values (regression of posterior capsule opacification) for some patients, negative EPCO values were created. The boxplots represent medians and quartiles. Evaluation of posterior capsule opacification (EPCO) values for the two different intraocular lenses at 5 years postoperatively, together with the last EPCO values obtained before capsulotomy for the 12 patients treated for posterior capsule opacification (PCO). The EPCO values at 2 months, regarded as baseline values, were subtracted from the values. As there was spontaneous improvement in EPCO values (regression of PCO) for some patients, negative EPCO values were created. The boxplots present medians and quartiles. The extent of PCO under the capsulorhexis area was quantified with EPCO for all time-points at which images of the posterior lens capsule had been obtained for all 59 patients (at 2 months, 1, 2, 3 and 5 years postoperatively). We previously reported spontaneous regression of PCO (Sundelin et al. 2005) in the same patient material during the first 3 years of follow-up. In the 5-year follow-up there was a natural increase in PCO, as well as minor regression and reforming and alterations of the PCO. No spontaneous regression of any clinical significance could be verified in the 59 patients. The question of whether a sharp-edged IOL optic prevents or delays PCO formation has been raised. Clinically and statistically the difference in PCO between the two silicone IOL designs remained consistent during the 5-year follow-up. Similar results have been published by Sacu et al. (2005), who compared two silicone IOLs with different optic edge designs in a 5-year follow-up. In this study, which included longterm morphological changes in PCO, our results were similar to those of Neumayer et al. (2005). Remodelling, some regression and increase in PCO were found on examination of the images obtained on all five occasions postoperatively. Only the area covered with PCO inside the capsulorhexis area was quantified. No regression of any clinical interest was found among these 59 patients, for each of whom a complete set of images was available. This work was supported in part by Pharmacia & Upjohn Sverige AB and by the Gothenburg Medical Society, Gothenburg, Sweden.