Early posterior capsular opacification after intercapsular cataract extraction and rigid Galand disc intraocular lens implantation.

From retrospective studies of implantation of the rigid Galand disc intraocular lens (IOL) and the Sinskey style J-loop IOL, we found that posterior capsular opacification was more common and developed faster in eyes implanted with a Galand disc IOL than in eyes implanted with a Sinskey style J-loop IOL. We investigated this further in a clinical study of 20 patients implanted with a Galand disc IOL. We found a specific type of posterior capsular haze, resembling a "moon landscape," in 10 (50%) of the 16 eyes (80%) with capsular fibrosis.     

Posterior capsular opacification and intraocular lens decentration. Part I: Comparison of various posterior chamber lens designs implanted in the rabbit model

Experimental phacoemulsification procedures were performed in 54 Rex rabbits. In 96 eyes, posterior chamber intraocular lenses (IOLs) were implanted in the capsular sac, and 12 eyes served as controls with no lens implantation. The IOLs were divided into eight groups consisting of both one-piece and three-piece styles with various optic designs. Each lens was evaluated for the relative effect on posterior capsular opacification (PCO) and optic decentration, two of the most common complications of modern cataract surgery and IOL implantation. Optics with a convex-anterior, plano-posterior design (the type of IOL optic most frequently implanted today) had the highest incidence of PCO. With capsular fixated IOLs, the features that have a statistically significant impact on reducing PCO include (1) one-piece, all-polymethylmethacrylate (PMMA) IOL styles, (2) a biconvex or posterior convex optic design, and (3) angulated loops. Lens decentration was not affected by the optic design, but statistical analysis showed that one-piece, all-PMMA IOL construction provided the most consistent centration.     

Effect of in-the-bag intraocular lens fixation on the prevention of posterior capsule opacification

PURPOSE: To compare the incidence of posterior capsule opacification (PCO) after extracapsular cataract extraction (ECCE) and phacoemulsification and to evaluate the role of posterior chamber intraocular lens (PC IOL) haptic fixation and biomaterial/design in reducing the incidence. SETTING: Postgraduate Institute of Medical Education and Research, Chandigarh, India; Center for Research on Ocular Therapeutics and Biodevices, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA. METHODS: This study comprised 278 eyes of 263 patients having ECCE and 318 eyes of 297 patients having phacoemulsification with PC IOL implantation. Posterior capsule opacification leading to a decrease in Snellen visual acuity of 2 or more lines was considered visually significant. The presence of PCO and IOL haptic fixation were evaluated postoperatively using slitlamp biomicroscopy. Haptic position was noted as in-the-bag (B-B), 1 haptic in the bag and 1 in the sulcus (bag-sulcus [B-S]), or both haptics out of the bag (sulcus-sulcus [S-S]). In addition, the rate of visually significant PCO was compared among 3 IOL biomaterials: poly(methyl methacrylate), silicone, and hydrophobic acrylic.Results: Visually significant PCO occurred in 42.45% of eyes having ECCE and 19.18% of eyes having phacoemulsification (P <.001, chi-square test) after a mean follow-up of 2.4 years +/- 0.7 (SD). In both groups, visually significant PCO was significantly less in eyes with B-B fixation than in those with B-S or S-S fixation (P <.001). The rate of visually significant PCO in all eyes in the phacoemulsification group with B-B fixation was low (11.90%) and was significantly lower in eyes with a hydrophobic acrylic IOL (2.22%; P <.05, chi-square test). CONCLUSIONS: In-the-bag PC IOL fixation is required to consistently reduce the incidence of PCO. Thorough removal of lens substance, including hydrodissection-assisted cortical cleanup, and in-the-bag PC IOL fixation seem to be the most important factors in reducing PCO, regardless of surgical procedure or IOL type used. Intraocular lens biomaterial and design also help prevent PCO.     

Factors that influence the development of posterior capsule opacification with a polyacrylic intraocular lens

PURPOSE: To identify factors that contribute to posterior capsule opacification (PCO) after implantation of a 5.5 mm polyacrylic (IOL). DESIGN: A retrospective analysis of a cohort of sequential images taken from the PCO database at St. Thomas' Hospital, London, to include all patients with an AcrySof MA30 lens and a 1-year retroillumination image. METHODS: Records of age, gender, axial length, and PCO measurements using the POCO software system were available. Images were divided into those with greater or less than 10% PCO. The degree of rhexis-IOL contact was recorded in clock hours. RESULTS: Images of 60 eyes were analyzed. Twenty-one eyes had more than 10% PCO. No correlation was found between PCO and age, gender, or axial length. Forty-eight eyes (80%) had some loss of rhexis-IOL contact. These eyes had increased PCO (P < .001) compared with eyes with complete IOL-rhexis contact. More PCO developed when the rhexis was partly on and partly off the IOL. CONCLUSIONS: PCO is reduced when the rhexis is in complete contact with the anterior IOL surface. The failure to achieve this accounts for the majority of increased PCO seen in patients implanted with this IOL model. PCO formation is related to surgical technique as well as IOL design, and comparisons cannot be made between IOLs without taking this into consideration. These results support the trend to the use of larger optic IOLs to prevent PCO and also support the "capsule compression" theory of PCO prevention.     

Effect of posterior chamber intraocular lens design and surgical placement on postoperative outcome.

Intraocular lens (IOL) design, optical configuration, and placement have potential effects on postoperative outcome. Laboratory studies have suggested that one-piece, biconvex designs may reduce or delay posterior capsular opacification and that in-the-bag fixation of the posterior chamber IOL may reduce inflammation. To document the clinical significance of IOL design and placement, we conducted a randomized, prospective, clinical trial. Six hundred uncomplicated capsulorhexis and phacoemulsification patients were randomized in a three-factor design to receive an IOL that was one-piece or three-piece, had a biconvex, plano-convex, or laser ridge optic, and was bag-or sulcus-fixated. Treatment differences were related to lens placement. Patients with bag-fixated IOLs had less posterior capsular opacification, fewer YAG laser capsulotomies, a higher percentage of centered lenses, less inflammation, and fewer late posterior capsular striae than those with sulcus-fixated IOLs. In the latter group, patients with three-piece IOLs had fewer posterior capsular striae at three months postoperatively. All six occurrences of haptic loop distortion were in patients with three-piece IOLs. Patients with the one-piece design had less late inflammation than those with the three-piece design. Fewer YAG capsulotomies were necessary at one year in patients with the biconvex design than in those with the plano-convex or laser ridge configurations. Operative complications, endothelial cell loss, and postoperative complications were not IOL-related.     

Preventive effect of a second-generation silicone intraocular lens on posterior capsule opacification

PURPOSE: To compare the preventive effect of a second-generation silicone intraocular lens (IOL) on posterior capsule opacification (PCO) with that of a soft acrylic IOL. SETTING: Jinshikai Medical Foundation, Nishi Eye Hospital, Osaka, Japan. METHODS: After phacoemulsification, a silicone IOL (PhacoFlex II) was implanted in 1 eye and an acrylic IOL (AcrySof) in the contralateral eye of 5 rabbits. RESULTS: The posterior view 3 weeks after surgery showed slightly more PCO in 3 eyes with the PhacoFlex II lens than in eyes with the AcrySof IOL, with the PCO obscuring the iris structures. In 2 eyes with an AcrySof IOL, slightly more PCO was seen. Histopathological examination revealed that a bend and complex folds in the posterior capsule were formed with both the PhacoFlex II and AcrySof IOLs. However, the capsular bend formed by the PhacoFlex II lens, which was caused by its blunt edge, was not as sharp as that with the AcrySof IOL and more PCO was seen in all eyes with a PhacoFlex II lens. CONCLUSIONS: Capsular bend formation does not necessarily require a sharp optic edge. A truncated optic rim of a certain thickness appears to form a bend. The capsule-bending does not appear to be an all-or-nothing effect. There seems to be a transition. That a capsular bend forms despite a blunt rather than a sharp optic edge may explain why the second-generation PhacoFlex II IOL prevents PCO better than first-generation and PMMA IOLs.     

直角边缘人工晶状体预防兔后囊膜混浊的实验研究

目的探讨直角边缘人工晶状体（intraocular lens，IOL）预防后囊膜混浊（posterior capsule opacification，PCO）的作用。方法30只新西兰兔进行超声乳化晶状体摘出联合囊袋内IOL植入术后，随机植入Crane OV-55CP、Crane OV-55C、Alcon TYPE 5C 3种IOL之一。观察术后并发症和PCO情况。术后3月行光镜和透射电镜检查，观察晶状体后囊膜的形态学变化。结果术后3月Crane OV-55CP组的PCO程度比Crane OV-55C和Alcon TYPE 5C组轻（P〈0．05），各组Soemmefing环形成程度无差异（P〉0．05）。病理学检查发现Crane OV-55CP组兔赤道部增生的晶状体上皮细胞在人工晶状体的直角边缘处受到了阻挡。Crane OV-55C和Alcon TYPE 5C组大量晶状体上皮细胞迁移至后囊膜。结论直角边缘IOL延缓了兔PCO的发生、发展，是预防PCO简便安全有效的方法。     

Role of posterior capsulotomy with vitrectomy and intraocular lens design and material in reducing posterior capsule opacification after pediatric cataract surgery

PURPOSE: To study the effect of primary posterior capsulotomy with anterior vitrectomy (PPC + AV) and intraocular lens (IOL) design and material on the development of posterior capsule opacification (PCO) after pediatric cataract surgery. SETTING: Tertiary care institution in India. PATIENTS: Sixty-four eyes of 52 children ranging in age from 3 months to 12 years who had cataract extraction with IOL implantation were prospectively evaluated for a minimum postoperative period of 2 years. METHODS: Thirty-two eyes received a hydrophobic acrylic lens with a truncated, square edge and 32, a single-piece poly(methyl methacrylate) (PMMA) lens that was not heparin surface modified. Sixteen eyes in each IOL group had PPC + AV; in the remaining 16 eyes in each group, the posterior capsule was left intact. RESULTS: Postoperatively, 25 eyes in the intact capsule group and 5 in the PPC + AV group developed PCO; the difference between groups was significant (P<.05). Of eyes with an intact capsule, 12 with an acrylic IOL and 13 with a PMMA IOL developed PCO (P>.05). In the PPC + AV group, 2 eyes with an acrylic IOL and 3 with a PMMA IOL developed PCO (P>.05). Overall, 14 eyes with an acrylic lens and 16 eyes with a PMMA lens developed PCO (P>.05). After surgery, there was a significant short-term delay in the development of PCO in the acrylic group (14 eyes; mean 6.66 months +/- 1.57 [SD]) compared to the PMMA group (16 eyes; mean 3.16 +/- 0.83 months) (P<.05). CONCLUSIONS: It is the management of the posterior capsule rather than IOL design and material that influences the incidence of PCO after cataract surgery in children. Development of PCO in the postoperative period was delayed with a hydrophobic acrylic IOL with square edges compared with a PMMA lens without square edges.     

Long-term effect of optic edge design in a silicone intraocular lens on posterior capsule opacification

PURPOSE: To compare the posterior capsule opacification (PCO) inhibiting effect of the round anterior and sharp posterior optic edge profile of the Clariflex silicone intraocular lens (IOL) [AMO Inc, Santa Ana, California, USA] with that of the double-round edge profile of the SI40 (Phacoflex; AMO Inc, Santa Ana, California, USA) silicone IOL over a period of three years. DESIGN: Prospective, randomized, double-masked, bilateral clinical trial. METHODS: The study took place at the Department of Ophthalmology, Medical University of Vienna, Austria. Fifty-two patients with age-related cataracts (104 eyes) were included in the study. Each patient received an SI40 IOL (round edges) in one eye and a Clariflex IOL with OptiEdge (sharp posterior optic edge) in the other eye. Follow-up examinations were at one week, one month, six months, and one, two, and three years. Digital retroillumination images were taken of each eye. The amount of PCO was subjectively assessed with the slit-lamp and objectively assessed by automated image analysis software (the computer program Automated Quantification of After-Cataract [AQUA]; Vienna, Austria) one, two, and three years after surgery. RESULTS: The Clariflex lens showed markedly less PCO at one, two, and three years after surgery. The mean AQUA PCO score was 1.39 for the SI40 and 0.56 for the Clariflex lens after one year, estimated at 1.64 and 0.57 after two years, and at 2.04 and 0.64, respectively, after three years (scale zero to 10; P < .001). The Nd:YAG laser capsulotomy rate was far higher in the SI40 group (Five cases vs one case at three years). CONCLUSIONS: The sharp posterior optic edge profile of the Clariflex silicone IOL led to marked and consistently less PCO than the round-edged SI40 IOL one, two, and three years after surgery.     

Comparison of design of intraocular lens versus the material for PCO prevention

AIM: To evaluate the influence of different intraocular lens(IOL) designs made of PMMA on posterior capsular opacification(PCO) and compare with foldable designs. METHODS: Phacoemulsification and IOL implantation was done in one eye of 24 New Zealand White rabbits, with IOL of two different designs (Square edged or round edge) and two different materials(PMMA or HEMA). After three months, the animals were sacrificed and enucleated. Evaluation of PCO included posterior view, migration of anterior capsular epithelial cells to the posterior capsule following epithelial-mesenchymal transition were assessed by staining the histological sections of posterior capsule by hematoxylin-eosin(HE) and Periodic acid- Schiff (PAS). The IOLs were extracted and stained with HE to evaluate the presence of adherent cells on the lens surface. RESULTS: PCO was highest with round edged rigid lens. There was no significant difference in the PCO between the square edged PMMA and square edged foldable lens. CONCLUSION: It is the design of the IOL not the material that offers protection on PCO formation.