Posterior capsular opacification and intraocular lens decentration. Part II: Experimental findings on a prototype circular intraocular lens design

In a prospective randomized study, 25 New Zealand white rabbit eyes were implanted with four intraocular lens (IOL) designs. These included a one-piece modified J-loop IOL, a three-piece modified J-loop IOL, a rigid disc IOL, and an experimental compressible disc (CD) IOL. The CD IOL revealed the lowest mean posterior capsular opacification (PCO) of all IOLs tested (P less than .01). With all lenses tested, a positive correlation between PCO and decentration was found (R = 0.55, P less than .05). These results suggest that because of its design features (i.e., one-piece construction, biconvex optic, posterior angulation of the fixation element), the CD lens produces a mechanical barrier against lens epithelial cell migration and reduces the incidence of PCO.     

Intraocular lens decentration and posterior capsule opacification: anatomo-pathologic findings after implantation of AMOSI40 IOLS

PURPOSE: To evaluate the incidence of intraocular lens (IOL) decentration and posterior capsule opacification (PCO) after implantation of a three-piece posterior chamber silicone IOL in a series of eyes examined postmortem. METHODS: Twenty-three pseudophakic enucleated human cadaver eyes, implanted with AMO SI40NB IOLs after phacoemulsification, were analyzed. Eyes obtained postmortem were sectioned at the equatorial plane and the anterior segment photographed from a posterior view. Location of IOL optic and haptics, type of fixation, and centration of IOL was evaluated. PCO was graded and the presence of Nd:YAG laser posterior capsulotomy was noted. RESULTS: Mean age at the time of surgery was 77.83 years, mean time since implantation was 18.26 months. In all the eyes examined, IOL haptics were positioned in the capsular bag. Mean decentration was 0.20+/-0.16 mm. No correlation was found between IOL decentration and time since implantation. The degree of peripheral PCO ranged from none (13.0%) to mild (39.1%) to moderate (26.1%) to severe (21.7%). The degree of central PCO ranged from none (52.2%) to mild (30.4%) to moderate (4.3%). Three patients (13.0%) underwent Nd:YAG laser posterior capsulotomy. CONCLUSIONS: A very good centration can be obtained when silicone AMOSI40NB IOLs are correctly implanted with the haptics inside the capsular bag. About half of the implants showed no central PCO while Nd:YAG laser posterior capsulotomy rates documented a relatively low PCO 18 months after surgery. A careful in the bag haptics placement is needed in order to reduce the IOL decentration and to prevent central PCO.     

Prospective experimental study of factors related to posterior chamber intraocular lens decentration.

The effect of posterior chamber intraocular lens (IOL) dimensions, design, style, loop fixation, and anterior capsular tears on decentration were investigated in an experimental model. Nine posterior chamber IOLs of various designs and styles with loop diameters between 12.0 and 14.0 mm and optic diameters between 5.0 and 7.0 mm were implanted in human eyes obtained post mortem. Symmetrical and asymmetrical fixation were investigated in eyes with and without radial tears using the Miyake posterior view technique. Location of IOL loops proved to be the most significant factor in IOL decentration. Decentration was least with symmetrical bag/bag fixation and no radial tears (mean = 0.20 +/- 0.05 mm). Asymmetrical bag/sulcus fixation in the presence of anterior capsular tears was associated with the highest decentration rate (mean 0.68 +/- 0.28 mm). Optic size and total loop diameter had no apparent effect on IOL centration in the immediate postoperative period.     

Scheimpflug measurement of intraocular lens position after piggyback implantation of foldable intraocular lenses in eyes with high hyperopia

PURPOSE: To investigate the position of 3-piece foldable intraocular lenses (IOLs) after piggyback implantation for high hyperopia. SETTING: University Eye Hospital, Johann Wolfgang Goethe University, Frankfurt am Main, Germany. METHODS: Eight eyes of 5 highly hyperopic patients had phacoemulsification and implantation of 2 foldable IOLs. In 3 eyes, both IOLs were implanted in the capsular bag. In 5 eyes, 1 IOL was placed in the capsular bag and the second IOL in the ciliary sulcus. Intraocular lens optic tilt and decentration, combined thickness of both IOLs, and anterior chamber depth (ACD) were measured postoperatively over a period of 18 months using Scheimpflug photography. RESULTS: All eyes with both IOLs in the capsular bag showed interpseudophakic opacification, with a mean increase in combined IOL thickness of 0.4 mm, a decrease in ACD of 0.3 mm, and a corresponding hyperopic shift of 4.00 diopters. Eyes in which the anterior IOL was placed in the ciliary sulcus showed no changes in refraction or combined IOL thickness. In these eyes, the anterior IOL had a higher mean decentration (0.49 mm +/- 0.20 [SD] after 12 months) than the posterior IOL (0.21 +/- 0.13 mm after 12 months). CONCLUSIONS: Piggyback IOL implantation with placement of 2 foldable IOLs in the capsular bag can be followed by a hyperopic shift that may be caused in part by displacement of the IOLs. Placement of the anterior IOL in the ciliary sulcus can lead to higher decentration of this IOL.     

囊袋张力环在半脱位晶状体的白内障手术中的临床应用

目的:评价囊袋张力环(capsular tension ring,CTR)在晶状体半脱位的白内障手术中的应用。方法:对15例15眼合并白内障的晶状体半脱位患者连续环形撕囊(continues curvilinear capsulorhexis,CCC)后植入CTR,然后行白内障超声乳化,及人工晶状体植入术。结果:所有15眼IOL正位,无倾斜及偏位,术后10～12mo观察矫正视力满意,未发现CTR引起的并发症。结论:CTR植入是治疗合并晶状体半脱位的白内障超声乳化的一种安全、有效的方法,可以防止人工晶状体偏位,减少手术并发症。     

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.     

Intraocular lens for correction of aphakia in cataract extraction through a small incision]

The purpose of this study was to create an intraocular lens (IOL) reliably fixed in the capsular sac and convenient for implantation through a tunnel incision. Our design consists from a biconcave lens 5 mm in diameter and 2 vis-a-vis C-shaped open haptic elements at an angle of 110 degrees to the optic component. The total diameter of IOL is 12 mm. The lens is made from rigid material (oligocarbonate methacrylate). IOLs of this design were implanted in 164 eyes. No complications were recorded. The studies indicate that this design ensures good mobility and elasticity of the supporting elements of the lens at the site of their bending and connection to the optic part. This results in even and most complete filling of the capsular sac equator with supporting elements and the maximal retraction of the sac, which creates conditions for reliable fixation of IOL, prevents development of fibrous changes, decentration and dislocation in the postoperative period.     

囊袋张力环在晶状体半脱位超声乳化白内障吸除术中的应用

目的：探讨将囊袋张力环植入晶状体半脱位的囊袋内进行超声乳化白内 障吸除术的安全性。方法：对13例（14只眼）合并晶状体半脱位（脱位范围1／3－3／4象限）的白内障患者行超声乳化白内障吸除术,术中注／吸晶状体皮质时,将囊袋张力环送入晶状体囊袋内,对脱位范围＞1／2象限者,将囊袋张力环用缝线固定在巩膜上。结果：术中人工晶状体植入晶状体囊袋内11只眼,植入睫状沟3只眼;术后人工晶状正位12只眼,人工晶状体轻度倾斜2只眼;术中常见并发症为囊袋撕裂和玻璃 体脱出。结论：囊袋张力环是超声乳化白内障吸除术治疗白内障合并晶状体半脱位患者的新型辅助工具,它具有提高手术安全性,防止人工晶状体偏位,减少手术并发症的优点。     

晶状体半脱位超声乳化吸出术中囊袋张力环的应用

目的评价晶状体囊袋张力环在白内障合并晶状体半脱位中行晶状体超声乳化吸出术中的应用价值。方法对15例(15眼)合并晶状体半脱位的白内障行晶状体超声乳化吸出术,术中连续环行撕囊后植入晶状体囊袋张力环,进行超声乳化吸出,囊袋内植入后房型人工晶状体,对晶状体半脱位范围>1/2圆周者,将囊袋张力环用缝线固定在悬韧带离断一侧巩膜壁上。结果术中人工晶状体植入囊袋内13眼,植入睫状沟2眼;所有植入的人工晶状体基本处于正位。结论在白内障合并晶状体半脱位中行晶状体超声乳化吸出术中植入囊袋张力环是安全有效的方法,它有利于保持囊袋的完整,便于手术操作,防止人工晶状体的偏位,减少手术并发症。     

Elapsed time for capsular apposition to intraocular lens after cataract surgery

OBJECTIVE: To examine when the anterior and posterior lens capsule completely become apposed to optics of silicone and acrylic intraocular lenses (IOLs) implanted after cataract surgery and to determine whether the different IOL materials influence the timing of completion of capsular contact. DESIGN: Randomized controlled clinical trial. PARTICIPANTS: Seventy eyes of 70 patients who were scheduled to undergo cataract surgery were randomly assigned to two groups using random number tables based on the type of IOL implanted: silicone or acrylic. Thirty-two patients in each group completed the follow-up. INTERVENTION: All eyes underwent phacoemulsification surgery with implantation of either a silicone or acrylic IOL. All IOLs were accurately placed into the capsular bag. MAIN OUTCOME MEASURES: Contact of the anterior and posterior lens capsule with the IOL optic surface was evaluated using the Scheimpflug videophotography system at 3, 5, 7, 9, 11, 14, 21, and 28 days after surgery. The postoperative day at which each capsule was completely apposed to the IOL optic was determined. In addition, anterior chamber depth was also measured. RESULTS: The anterior capsule was in contact with the IOL optic on the same day or earlier than the posterior capsule in all patients. Complete apposition of the IOL was observed significantly earlier with silicone IOLs than with acrylic IOLs with both the anterior capsule (6.2 versus 3.6 postoperative days; P < 0.0001) and the posterior capsule (11.1 versus 7.4 postoperative days; P = 0.0339). No significant change in mean anterior chamber depth was observed with the silicone IOL, whereas there was significant anterior shift after implantation of the acrylic IOL. CONCLUSIONS: Capsular contact with the IOL optic is completed within approximately 8 days after cataract surgery with silicone IOLs and 11 days with acrylic IOLs. Complete apposition to both the anterior and posterior capsule was significantly earlier with silicone IOLs than with acrylic IOLs.