To compare the preventive effect on posterior capsule opacification (PCO) of an acrylic intraocular lens (IOL) and a silicone IOL, both with sharp rectangular optic edges. Jinshikai Medical Foundation, Nishi Eye Hospital, Osaka, Japan. After phacoemulsification, an acrylic IOL (AcrySof(R)) was implanted in 1 eye and a silicone IOL (CeeOn 911) in the contralateral eye of 7 rabbits, one of which was omitted from evaluation. The Miyake-Apple view and histopathological findings 3 weeks after surgery revealed that the lens capsule wrapped tightly around the optic edges, conforming to a distinctly sharp bend, with both IOL types in 5 rabbits. Migrating lens epithelial cells (LECs) were inhibited at the site. The AcrySof IOL had a better capsular bend effect in the histological sections, but there was no apparent difference in PCO development between the 2 IOLs. The CeeOn 911 silicone IOL, with sharp rectangular optic edges, showed an effect on preventing PCO that was similar to that of the AcrySof IOL. When a discontinuous capsular bend is created by an IOL with sharp optic edges, the bend may induce contact inhibition of migrating LECs regardless of the lens' material composition.

To evaluate how and how fast a capsular bend is created clinically at the optic edge of an intraocular lens (IOL) after cataract surgery. Jinshikai Medical Foundation, Nishi Eye Hospital, Osaka, Japan. Capsular bend formation was observed by slitlamp after maximum pupil dilation in 45 eyes of 45 patients with senile cataract. Fifteen eyes each received an AcrySof MA60BM acrylic (Alcon), PhacoFlex II SI-40NB silicone (Allergan), or UV26T poly(methyl methacrylate) (PMMA) (Menicon) IOL. Patients were evaluated prospectively at 1 day and 1, 2, and 4 weeks and retrospectively (15 eyes per IOL) 1 year after cataract surgery. A capsular bend index was developed to document and categorize the capsular bend formation process at the IOL optic edge. The anterior and posterior capsules adhered, with the latter attracted to the former. The adhesion always progressed from the periphery to the optic edge so that the posterior capsule eventually wrapped around the posterior optic edge, although not fully circumferentially in all cases. The process took place in 4 stages. Capsular bend formation was complete 1 month after surgery with the foldable IOLs (AcrySof, PhacoFlex II) but was significantly delayed with the PMMA IOL. After 1 year, the capsular wrapping was firm and fully circumferential at the optic edge with all IOL types in all cases. Capsular bend formation progressed in the same fashion but at significantly different speeds among the IOLs, suggesting that the process depends on IOL material and design. Fast, early capsular bend formation may be 1 reason AcrySof and PhacoFlex II IOLs prevent PCO statistically better than PMMA IOLs. The results indicate that PCO is prevented by the sharp capsular bend created by sharp optic edges and by quick bend formation.

To clarify the extent to which the adhesiveness of an acrylic material influences the formation of posterior capsule opacification (PCO). Jinshikai Medical Foundation, Nishi Eye Hospital, Osaka, Japan. Two types of AcrySof(R) intraocular lenses (IOLs) were prepared: round edged and tumbled. The AcrySof with round edges was implanted in 1 eye in a group of 4 rabbits and the tumbled IOL, in 1 eye in a group of 5 rabbits. In both groups, the contralateral eye received a conventional AcrySof with sharp optic edges. A histopathological examination was performed 3 weeks after surgery. With the round-edged AcrySof IOL, no capsular bend formed at the optic edge and abundant lens epithelial cells (LECs) migrated posteriorly. With the sharp-edged AcrySof lens, a sharp capsular bend formed and LEC migration was significantly inhibited. In eyes with a tumbled IOL, a capsular bend was created, but it was less marked than that created by the sharp-edged lens and there was slightly more LEC migration posteriorly. The AcrySof IOL lost its preventive effect on PCO when the optic was rounded. The effect of the AcrySof lens in preventing PCO is mainly a result of its rectangular, sharp-edged optic design. The acrylic material may play a complementary role by helping create a sharp capsular bend. Capsular bend formation is the key to the PCO preventive effect of an IOL.

To compare the preventive effect of 4 types of design- and material-matched intraocular lenses (IOLs) on posterior capsule opacification (PCO). Jinshikai Medical Foundation, Nishi Eye Hospital, Osaka, Japan. After phacoemulsification, 1 of 2 matched IOLs in 3 groups was implanted in 1 eye and the other IOL in the contralateral eye of 4 to 6 rabbits. Three weeks postoperatively, posterior view and histopathological evaluations were performed and the capsular bending effect and amount of PCO evaluated. The capsular bending effect was similar between a sharp-edged acrylic IOL (Sensar 40e, AMO) and a sharp-edged silicone IOL (ClariFlex, AMO) and between the Sensar 40e IOL and a sharp-edged acrylic IOL (AcrySof, Alcon Laboratories). There was no significant difference between IOL types in the amount of PCO. The capsular bend effect was slightly better and the PCO amount slightly less with the ClariFlex IOL than with the round-edged silicone PhacoFlex II IOL (AMO). There was no substantial difference in PCO prevention between IOLs with sharp posterior optic edges, regardless of the IOL's material composition. The anterior edge design appeared to have no preventive effect. These results confirm that a sharp posterior optic edge is the main factor in preventing PCO.

To investigate whether the lens epithelial cells (LECs) at the capsular bend created by a sharp-edged intraocular lens (IOL) are in the G(0) phase of the cell cycle. Nishi Eye Hospital, Osaka, Japan. A CeeOn Edge silicone IOL (AMO) with sharp edges was implanted in 1 eye and a PhacoFlex II silicone IOL (AMO) with rounded edges in the contralateral eye after standard cataract surgery in 6 rabbits. Immunohistochemical staining for the Ki-67 antibody was performed 1 day, 3, 4, and 7 weeks after surgery. In eyes with the sharp-edged IOL, LECs with thin, elongated nuclei accumulated at, but did not extend beyond, the capsular bend and stained negative for the Ki-67 antibody, indicating that they were in the G(0) phase of the cell cycle. In contrast, in the eye with the round-edged IOL, continuous migration of a predominantly monolayer of LECs over the IOL and onto the posterior capsule occurred. These cells were Ki-67 positive, indicating that they were proliferating. Lens epithelial cells at the capsular bend of sharp-edged IOLs were in the G(0) phase of the cell cycle, indicating that they were contact inhibited. These findings support the theory the sharp posterior optic edge of the IOL inhibits LEC migration, reducing formation of posterior capsule opacification. Whether these LECs can reactivate when the capsular bend is eliminated by later formation of a Soemmerring's ring requires further studies.

To evaluate the preventive effect of a capsular bending ring on anterior and posterior capsule (PCO) opacification in a 2 year clinical study. Jinshikai Medical Foundation, Nishi Eye Hospital, Osaka, Japan. This study comprised 60 patients with senile cataract (35 women, 25 men) with a mean age of 69 years. An open poly(methyl methacrylate) capsular bending ring with a truncated edge profile designed to create a sharp bend in the equatorial capsule was implanted in 1 eye of patients with a hydroxyethyl methacrylate intraocular lens (IOL). The contralateral eye, which acted as a control, received an IOL but no ring. Patients were examined 6 months (n = 52), 1 year (n = 48), and 2 years (n = 42) postoperatively. Anterior capsule opacification was determined by slitlamp evaluation. Anterior capsule shrinkage (area within the capsulorhexis) and PCO were evaluated and scored using a computer software package for image analysis. Posterior capsule opacification was also measured by the rate of neodymium:YAG (Nd:YAG) capsulotomies. Anterior capsule opacification and shrinkage were significantly less in eyes with the ring. The mean PCO score was 0.235 +/- 0.215 (SD), 0.287 +/- 0.200, and 0.398 +/- 0.248 with the ring and 0.530 +/- 0.190, 0.670 +/- 0.225, and 1.111 +/- 0.298 without the ring at 6 months, 1 year, and 2 years, respectively (P <.01 at each follow-up). An Nd:YAG laser capsulotomy was performed in 4 eyes with and 17 eyes without the ring after 2 years (P <.01). The capsular bending ring significantly reduced anterior capsule fibrosis and shrinkage as well as PCO. The ring may be useful in patients who are at high risk of developing eye complications from capsule opacification that require Nd:YAG laser capsulotomy, in those expected to have vitreoretinal surgery and photocoagulation, and in cases of pediatric cataract.