A mathematical model of factors that influence the performance of accommodative intraocular lenses

In this work a mathematical model of capsule movement during pseudophakic accommodation is described to allow identification and evaluation of factors that may explain the variation in effect of accommodative intraocular lenses (IOLs) between patients. The model assumes that increasing vitreous pressure pushes the lens capsule forward as a circular diaphragm and that this movement is from a fixed fulcrum. With an IOL in situ, the capsule is taken to have a non-uniform thickness due to the presence of the anterior capsulorhexis. The model assumes a uniform capsular elasticity and ignores contributions from cellular elements such as posterior capsule opacification. Using our model and a regression formula to calculate capsular bag size, taking into account axial length and keratometry values, we are able to predict accommodative effect in individual patients. By simple geometry we have developed a mathematical model to identify variables that are important in pseudophakic accommodation. It provides the basis for the development of a more complex model that would address the movement of a lens taking into account the influence of the zonular system during accommodation.     

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.     

In situ tumbling of the AcrySof intraocular lens

The small incision through which foldable acrylic intraocular lenses (IOLs) are implanted does not allow easy explantation of the lens in the event of intraoperative complications. Reversal of the IOL optic during insertion, although rare, can predispose to postoperative complications such as pupillary capture of the IOL, capsule bag distension syndrome, and refractive problems. Explanting the IOL can damage it, the cataract wound, or both. We describe a technique of in situ tumbling of the AcrySof IOL to correct reversed-optic implantation that preserves the integrity of the IOL and anterior segment structures.     

Shape of lens epithelial cells after intraocular lens implantation

PURPOSE: To evaluate the morphological behavior of lens epithelial cells (LECs) after human cataract surgery with implantation of a poly(methyl methacrylate) (PMMA) or silicone intraocular lens (IOL). SETTING: Department of Ophthalmology, Fujita Health University, Banbuntane Hotokukai Hospital, Nagoya, Aichi, Japan. METHODS: Morphological observations of LECs in the patients with IOLs were made by light and transmission electron microscopy. The LECs were from 4 areas: (1) the region below the anterior capsule, touching the IOL; (2) the area between region 1 and the equatorial region; (3) the equatorial region; and (4) the central equatorial region and of the posterior capsule not touching the IOL. Case 1 had implantation of a single-piece IOL with a PMMA optic and haptics. Case 2 had a 3-piece IOL with a PMMA optic and polypropylene haptics. Case 3 had a 3-piece IOL with a silicone optic and polypropylene haptics. Areas 1 and 4 could not be observed in Case 2. RESULTS: The major difference between the patient with a PMMA IOL (Case 1) and the patient with a silicone IOL (Case 3) was that among the 4 areas observed, collagen fibers were present only in area 1 in Case 1 but in areas 2 or 3 as well in Case 3. CONCLUSIONS: Fibrous collagen fibers appeared in regions in which LECs adhered and there was capsule contact with the IOL optic. In addition fibrous collagen fibers appeared in more areas in the eye with the silicone IOL than in that with the PMMA IOL, perhaps because IOLs with silicone optics move slightly while in the capsular bag.     

Intraocular lens optic capture

A continuous curvilinear capsulorhexis (CCC) provides a tear-resistant opening that allows use of a technique of capturing the intraocular lens (IOL) optic through the capsulorhexis opening when the opening is at least 1.0 to 2.0 mm smaller than the optic diameter. The technique provides stability and long-term centration of the IOL and prevents vitreous from extending anterior to the IOL. This paper reviews the current variations of optic capture including (1) haptics in the sulcus and IOL optic capture through a CCC, (2) haptics in the sulcus and IOL optic capture through an anterior capsule opening and a posterior CCC (PCCC), (3) haptics in the capsular bag and IOL optic capture through a PCCC, (4) haptics in the capsular bag and IOL optic capture through an anterior CCC, (5) haptics in the sulcus and IOL capture through a capsular membrane opening, and (6) haptics posterior to the capsular bag and IOL capture through a capsular membrane opening.     

Effect of optic edge design and haptic angulation on postoperative intraocular lens position change

PURPOSE: To assess the effect of optic edge design and optic-haptic angulation of open-loop intraocular lenses (IOLs) on postoperative axial movement and the final position of the optic by measuring the anterior chamber depth (ACD) during the first postoperative year using partial coherence interferometry (PCI). SETTING: Department of Ophthalmology, Vienna General Hospital, Institute of Medical Physics, University of Vienna, Vienna, Austria. METHODS: In study 1, a 3-piece silicone IOL with nonangulated modified C-loop haptics (MicroSil, Dr. Schmidt) was implanted in 78 eyes of 39 patients; patients were randomized to receive a round-edged optic IOL in 1 eye and a sharp-edged optic IOL in the other eye. The ACD was measured by PCI 1 day, 1 week, 3 months, and 1 year after surgery. In study 2, a foldable, 3-piece acrylic IOL with modified 10-degree angulated J-loop haptics (AcrySof MA60BM, Alcon) was implanted in 32 eyes of 32 patients. The ACD was measured by PCI 1 day, 1 week, and 3 months after surgery. RESULTS: In eyes with a nonangulated silicone IOL, there was a significant postoperative change in ACD with both sharp-edged and round-edged designs (P<.01). There was forward movement of both IOL designs in the first week, with no significant difference between the 2 models. From 1 week to 3 months, there was backward movement of IOLs of both designs, with the sharp-edged IOL moving a significantly greater amount (P<.001). From 3 months to 1 year, IOLs with both optic edge designs moved slightly backward. Sixty-six percent of angulated IOLs showed continuous but variable forward movement and 34%, backward movement. CONCLUSIONS: Optic edge design influenced postoperative axial optic movement and thus had an impact on the development of postoperative refraction (refractive shift, deviation from target refraction). The influence of optic-haptic angulation proved to be significantly greater and more variable than edge design.     

拟调节人工晶状体的临床应用与进展综述

良好的调节是人眼视功能重要的组成部分,能为我们提供不同距离清晰的视觉图像。单焦点人工晶状体,不能满足患者术后中、近距离用眼的需求。多焦点人工晶状体是利用特殊的光学设计,将进入眼内的光线分配到远、中、近的不同焦点聚焦,从而提供全程视力;而可调节人工晶状体则采用了类似人类晶状体的调节原理,通过人工晶状体的光学部在囊袋内前后位置移动,来改变光学节点,从而达到既能看远,也能看近的目的。本文就多焦点和可调节型人工晶状体的特点、临床应用,特别是其术后效果和可能出现的视觉症状做一综述。     

Refractive lensectomy and accommodating lens implantation in a case of hyperopia

We present a 39-year-old woman with high hyperopia who developed an intolerance to contact lenses due to dry-eye syndrome and Grave's disease. Refractive lensectomy with implantation of a custom-made +31.00 diopter (D) accommodating intraocular lens (IOL) (1CU, HumanOptics) was performed in both eyes. This foldable IOL has modified haptics with transmission elements that allow axial movement of the IOL optic and capsular bag secondary to contraction of the ciliary muscle. The calculated pseudophakic accommodation induced by the anterior shift of a +31.00 D IOL is 2.20 D per millimeter of axial displacement. After 6 months, the accommodative range determined by defocusing was 3.00 D. The subjective near point with best distance correction was 32.00 cm. Refractive lensectomy and implantation of an accommodating IOL based on focus shift may be a refractive solution in eyes with high hyperopia and a short axial length.     

Perioperative complications of intraocular lens exchange in patients with opacified Aqua-Sense lenses

PURPOSE: To evaluate the perioperative complications of intraocular lens (IOL) exchange in 25 eyes of 22 patients with opacified Aqua-Sense IOLs (Ophthalmic Innovations International). SETTING: Department of Ophthalmology, University Hospital Aintree, Liverpool, United Kingdom. METHODS: The study comprised 22 patients (25 eyes) who had previous phacoemulsification and implantation of Aqua-Sense single-piece hydrophilic acrylic IOLs in the capsular bag and developed severe late opacification of the IOL. All patients reported glare and deterioration in vision. The IOLs were explanted and replaced with new lenses. The perioperative complications were evaluated. The best corrected visual acuity (BCVA) before and after surgery was compared. RESULTS: In 24 eyes, the opacification was complete, involving the optic, haptics, and substance of the IOLs. Uneventful IOL exchange and placement of a new IOL in the bag was achieved in 13 eyes (52%). Complications occurred in the remaining 12 eyes (48%). Ten eyes (40%) developed zonular dehiscence, 4 (16%) of which were managed with anterior chamber IOL implantation. One eye (4%) developed posterior capsule rupture and 1 eye (4%), posterior capsule rupture and zonular dehiscence. The cornea decompensated in 2 eyes (8%). One eye (4%) developed Pseudomonas keratitis. The mean BCVA (decimal scale) before and after IOL exchange was 0.57 +/- 0.24 and 0.60 +/- 0.28, respectively. There was no significant difference in visual acuity between before and after IOL exchange (P=.782, paired t test). CONCLUSIONS: Explantation of Aqua-Sense IOLs was challenging because of the tight adherence of the optic and haptics to the capsule. Long-term follow-up of patients with Aqua-Sense IOLs should be maintained.     

Combined cataract surgery and 25-gauge sutureless vitrectomy for posterior lentiglobus

Combined cataract surgery and sutureless vitrectomy were performed in a 2-year-old boy with posterior lentiglobus. After an anterior capsulotomy was made, the lens nucleus was aspirated without hydrodissection to avoid posterior capsule rupture. The cortex was carefully aspirated because the central posterior capsule moved up and down during irrigation and aspiration. A pars plana vitrectomy was then performed with the sutureless 25-gauge system for an anterior vitrectomy with a posterior capsulotomy. A +27 diopter AcrySof intraocular lens (IOL) (Alcon) was implanted with the haptics in the bag and the optic behind the posterior capsulotomy with optic capture. Two months postoperatively, the IOL was centered and there were no complications. This surgical technique is easy and effective. It avoids complications, facilitates IOL implantation behind the posterior capsule, and improves the external appearance of the eye immediately postoperatively.     

Intraoperative management of posterior capsule tears in phacoemulsification and intraocular lens implantation

OBJECTIVE: This paper presents the incidence, causes, and management of posterior capsule (PC) tears and their postoperative outcomes in a large series of eyes that underwent cataract removal and intraocular lens (IOL) implantation, operated on by one surgeon. DESIGN: Retrospective, noncomparative case series. PARTICIPANTS: Eighteen thousand four hundred seventy consecutive eyes (1992-1999) were reviewed with the assistance of electronic medical records for incidence of PC tears in patients seeking treatment at an outpatient cataract surgery clinic. INTERVENTION: Eyes in this series underwent continuous curvilinear capsulorrhexis (CCC), nucleofractis phacoemulsification, and IOL implantation under topical anesthesia. Different intraoperative surgical strategies such as posterior continuous curvilinear capsulorrhexis (PCCC) were used in the management of PC tears. MAIN OUTCOME MEASURES: Routine preoperative and postoperative visual and refractive outcomes were recorded, including incidence of lens capsule tears, IOL position, and postoperative complications. RESULTS: Posterior capsule tears occurred in 83 of 18,470 eyes, resulting in an overall incidence of 0.45%. Of these 83 eyes with PC tears, 49% received vitrectomy. Fifty-one of 83 PC tears (61.4%) were amenable to be converted to PCCC. Of these 51 procedures, 50 eyes had PC IOL in-the-bag fixation. One eye had PCCC with optic capture. There were no eyes with dropped nuclei or nuclear fragments requiring pars plana vitrectomy. Seventeen eyes (20.5%) had Neuhann anterior capsule rhexis fixation with the haptics placed in the sulcus and IOL securely in the bag. Ten eyes (12.1%) had the IOL placed in the sulcus, and 5 eyes (6.0%) required anterior chamber IOL fixation. None of the 83 PC tears resulted in clinically evident cystoid macular edema, retinal detachment, or endophthalmitis. CONCLUSIONS: With an intact CCC and with conversion of PC tears to PCCC, in-the-bag fixation of IOLs can be achieved in most eyes.     

Accommodating intraocular lenses: a critical review of present and future concepts

Background Significant efforts have been made to develop lens implants or refilling procedures that restore accommodation. Even with monofocal implants, apparent or pseudoaccommodation may provide the patient with substantial though varying spectacle independence. True pseudophakic accommodation with a change of overall refractive power of the eye may be induced either by an anterior shift or a change in curvature of the lens optic. Materials and methods Passive-shift lenses were designed to move forward under ciliary muscle contraction. This is the only accommodative lens type currently marketed (43E/S by Morcher; 1CU by HumanOptics; AT-45 by Eyeonics). The working principle relies on various hypothetical assumptions regarding the mechanism of natural accommodation. Dual-optic lenses were designed to increase the dioptric impact of optic shift. They consist of a mobile front optic and a stationary rear optic which are interconnected with spring-type haptics. With active-shift lens systems the driving force is provided by repulsing mini-magnets. Lens refilling procedures replace the lens content by an elastic material and provide accommodation by an increase of surface curvature. Results Findings with passive-shift lenses have been contradictory. While uncorrected reading vision results were initially reported to be favorable with the 1CU, and excellent with the AT-45 lens, distant-corrected near vision did not exceed that with standard monofocal lenses in later studies. Mean axial shift from laser interferometric measurements under stimulation with pilocarpine showed a moderate anterior shift with the 1CU, while the AT-45 paradoxically exhibited a small posterior shift. With the 1CU, the shift-induced accommodative effect was calculated to be less than +0.5 D in most cases, while +1 D was achieved in a single case only. Ranges and standard deviations were very large in relation to the mean values. Under physiological near-point stimulation, however, no shift was seen at all. Prevention of capsule fibrosis by extensive capsule polishing did not enhance the functional performance. Dual optic lenses are under clinical investigation and are reported to provide a significant amount of accommodation. However, possible long-term formation of interlenticular opacifications remains to be excluded. Regarding magnet-driven active-shift lens systems, initial clinical experience has been promising. Prevention of fibrotic capsular contraction is crucial, and it has been effectively counteracted with a special capsular tension ring, or lens fixation technique, together with capsule polishing. Lens refilling has been extensively studied in the laboratory and in primates. Though it offers great potential for fully restoring accommodation, a variety of problems must be solved, such as achieving emmetropia in the relaxed state, adequate response to ciliary muscle contraction, satisfying image quality over the entire range of accommodation and sustained functioning. The key problem, however, is again after-cataract prevention. Conclusions As opposed to psychophysical evaluation techniques, laser interferometry measures what shift lenses are designed to provide: axial shift on accommodative effort. While under pilocarpine some movement was recorded, no movement at all was found under near-point stimulation with any of the lenses currently marketed. In contrast, magnetic-driven active-shift lens systems carry the potential of sufficiently topping up apparent accommodation to provide for clinically useful accommodation while using conventional lens designs with proven after-cataract performance. Dual optic implants significantly increase the impact of axial optic shift. The main potential problem, however, is delayed formation of interlenticular regenerates. Lens refilling procedures offer the potential of fully restoring accommodation due to the great impact of increase in surface curvature on refractive lens power. However, various problems remain to be solved before clinical use can be envisaged, above all, again, after-cataract prevention. The concept of passive single-optic shift lenses has failed. Concomitant poor capsular bag performance makes these lenses an unacceptable trade-off. Magnet-assisted systems potentially combine clinically useful accommodation with satisfactory after-cataract performance. Dual optic lenses theoretically offer substantial accommodative potential but may allow for interlenticular after-cataract formation. Lens refilling procedures have the greatest potential for fully restoring natural accommodation, but will again require years of extensive laboratory and animal investigations before they may function in the human eye. The author has no proprietary interest in any of the materials or equipment mentioned in this study.     

Effect of the hydrophilicity of acrylic intraocular lens material and haptic angulation on anterior capsule opacification

AIM: To evaluate the influence of hydrophilic and hydrophobic acrylic material and haptic angulation on anterior capsule opacification (ACO). METHODS: Prospective study on 53 patients with bilateral age-related cataract. Patients underwent standard cataract surgery by the same surgeon and randomly received a hydrophilic acrylic intraocular lens (IOL) in one eye and a hydrophobic acrylic IOL in the other eye. Forty five of these patients completed the one-year follow-up. The following parameters were assessed: decentration, buttonholing, anterolenticular gap (ALG), ACO, outgrowth and refractive outcome. RESULTS: At the one-year follow-up, ACO was seen in 80% of the hydrophilic and 100% of the hydrophobic IOLs. ACO was more intense in the hydrophobic IOLs (p<0.001). Outgrowth was seen in 42% of the hydrophilic and 2% of the hydrophobic IOLs (p = 0.0003). No case of persisting ALG was seen in the hydrophobic IOLs, but in 42% of the hydrophilic IOLs. The refractive outcome was -0.29 (SD 0.56) dioptres for the hydrophilic and 0.003 (SD 0.44) dioptres for the hydrophobic IOLs (p<0.001). CONCLUSION: These results suggest that there is less ACO in hydrophilic acrylic than in hydrophobic acrylic IOLs. Although material properties might play a role, the angulated haptics of the hydrophilic IOLs exert an additional effect by the persisting ALG and a lack of contact between the IOL and the anterior capsule.     

Interlenticular opacification associated with asymmetric haptic fixation of the anterior intraocular lens

PURPOSE: To describe the occurrence of interlenticular opacification in association with asymmetric haptic fixation of the anterior intraocular lens in a patient who had two intraocular lenses (IOLs) inserted for axial hyperopia. DESIGN: Observational case report. METHODS: An 83-year-old patient underwent uncomplicated cataract extraction and piggyback IOL insertion. The posterior IOL was placed within the capsule, but one of the haptics of the anterior IOL was inadvertently placed in the ciliary sulcus and the other in the capsule. RESULTS: Interlenticular opacification was localized to the interlenticular area near the anterior lens haptic placed within the capsule and absent from the interlenticular area near the anterior lens haptic fixated in the ciliary sulcus. CONCLUSION: This case report supports the idea that sulcus placement of the anterior IOL helps to prevent interlenticular opacification.     

拟调节人工晶状体在眼内位移与调节力研究

目的 探讨拟调节人工晶状体在眼内位移与调节力的关系.方法 采用病例对照研究方法,将白内障患者20例(20只眼)分成两组:10只眼植入Lestec公司生产的福来视拟调节人工晶状体(TetraflexIOL)(福来视组);另外10只眼植入其他无调节功能的人工晶状体(单焦点组).检测患者术后的裸眼远、中、近视力及矫正远、中、近视力;矫正远视力的近视力;采用前段OCT定量测定1%pilocarpine诱导缩瞳后人工晶状体在眼内前后移动的幅度;同时观察患者调节力的变化.结果 所有患者随访3个月:两组的裸眼、矫正远视力及矫正近视力差异均无统计学意义(P＞0.05);福来视组的裸眼中、近视力及矫正远视力的近视力均优于对照组(P<0.05);福来视组人工晶状体移动度及调节力与对照组比较差异有统计学意义(P<0.05),而且人工晶状体移动度与调节力呈正相关(r=0.977.P=0.000).结论 福来视拟调节人工晶状体是安伞有效的,能使患者术后获得一定的调节力,与人工晶状体的移动度具有正相关性,提供良好的远、中、近视力.     

Pseudophakic accommodation with translation lenses – dual optic vs mono optic

PURPOSE: To investigate the pseudophakic accommodation effect in dual and mono optic translation accommodative intraocular lenses (AIOL) using linear matrix methods in the paraxial space. METHODS: Dual (anterior optic of power +32 D linked to a compensatory posterior optic of negative power) and mono lens power was determined in the non-accommodated state using linear geometric optics based on the Gullstrand model eye. The position of the AIOL was calculated from a regression formula. Pseudophakic accommodation was assessed with three systems: (1) forward shift of the mono optic lens, (2) anterior translation of the anterior optic in the dual optic lens system with an unchanged position of the posterior minus lens and (3) symmetrical anterior and posterior translation of the anterior and posterior lens. The Gullstrand model eye was modified by changing the axial length (and proportionally changing the phakic anterior chamber depth) to investigate the accommodative effect in myopic and hyperopic eyes. RESULTS: The dual optic lens system (2) yields a nearly constant accommodation amplitude of 2.4-2.5 D mm(-1) movement over the total range of axial lengths. The mono optic lens (1) provides a higher accommodative effect only in extremely short eyes (high refractive power of the lens), whereas for normal eyes (1.4-1.5 D mm(-1) movement) and for long (myopic) eyes the accommodative effect is much less than the dual optic lens. The dual optic lens system under condition (3) yields less accommodation amplitude compared with the dual optic system under condition (2) over the total range of axial length but provides higher accommodation amplitude compared with the mono optic lens system (1) with axial lengths greater than 22.3 mm (lens power 25.5 D). In the accommodated state, with lens translation of 1 mm, the absolute value of the lateral magnification increases with the refractive power of the mono optic lens (1) and decreases in both dual optic lens systems (under conditions 2 and 3). CONCLUSIONS: A mathematical strategy is presented for calculation of the accommodative effect of mono-optic and dual optic AIOL. The dual optic lens yielded a nearly constant accommodation amplitude of about 2.4-2.5 D mm(-1) translation, whereas the mono optic lens yielded an accommodative response of <2 D mm(-1) translation in long myopic or normal eyes. Only in extremely short eyes is the accommodative amplitude of the mono-optic lens higher than the dual optic lens.     

Posterior capsulorhexis combined with optic buttonholing: an alternative to standard in-the-bag implantation of sharp-edged intraocular lenses? A critical analysis of 1000 consecutive cases

BACKGROUND: Current after-cataract prevention relies on optimizing the natural barrier effect of the optic rim against lens epithelial cell (LEC) migration. However, deficiencies in circumferential capsular bag closure caused by the intraocular lens (IOL) haptic or delayed secondary re-division of the fused capsules by Soemmering s ring formation lead to primary or secondary barrier failure. Consequently, surprisingly high posterior laser capsulotomy rates have been reported long-term, even with optimal capsular surgery and the most widespread hydrophobic acrylic IOLs, considered to be the most advanced. Intraoperative removal of the central posterior capsule has been shown to be effective in further reducing LEC immigration. However, efficacy has turned out to be limited because of the propensity of LECs to use the posterior optic surface as an alternative scaffold. MATERIAL AND METHODS: Technique: in pediatric cataract surgery, buttoning-in of the optic into an adequately-centered posterior capsulorhexis opening has been described previously. This technique was further elaborated and applied as the standard technique in a large series of adult eyes. In general, the diameter aimed at was 5-6 mm for the anterior, and 4-5 mm for the posterior capsulorhexis. Between September 2004 and June 2007, 1000 consecutive cases have thus been performed and systematically evaluated. One hundred and fifty eyes additionally underwent extensive anterior LEC abrasion. Another sub-series investigated the option of further reducing capsular fibrosis by creating an anterior capsulorhexis larger than the optic. Evaluation: special scrutiny was applied to detect postoperative vitreous entrapment. Regeneratory and fibrotic after-cataract formation were both meticulously followed-up. Postoperative pressure course, anterior segment inflammation, macular thickness and morphology, as well as axial optic stability and optic centration, were evaluated in intraindividual comparison studies. RESULTS: A low rate of vitreous complications was found, which can be avoided by appropriate surgery. Vitreous entanglement occurred in six eyes, and vitreous herniation after PPCCC over-sizing in two. In three, anterior vitrectomy was performed. There was only one single case of retinal detachment-supposedly unrelated to the technique itself-and no case of cystoid macular edema. Retro-optical regenerate formation was completely abolished, while fibrosis was drastically reduced by the posterior capsule sandwiched in between the anterior LEC layer on the backside of the anterior capsule and the anterior optic surface, thereby blocking contact-mediated myofibroblastic LEC transdifferentiation. Additional capsular polishing further reduced residual fibrosis emerging from the anterior capsule contacting the optic adjacent to the haptic junction, as well as regeneratory LEC re-proliferation on the posterior capsule overlying the optic. Postoperative pressure course was almost identical to that found after standard in-the-bag implantation of the IOL, as was flare, and macular thickness and morphology. As opposed to bag-fixated IOLs, no axial movement of the optic was detected. IOL optics always perfectly centered even when the capsular opening was not optimally centered. Due to the exquisite stretchability and elasticity of the posterior capsule, the 6-mm IOL optic could safely be buttoned-in in a posterior capsulorhexis of 4 mm and smaller. CONCLUSIONS: Posterior optic buttonholing (POBH) is a safe and effective technique which not only excludes retro-optical opacification, but also withholds capsular fibrosis by obviating direct contact between the anterior capsular leaf and the optic surface. Anterior LEC abrasion significantly reduced both the residual fibrosis and regeneratory LEC proliferation. Apart from pediatric cataract, POBH is currently recommended for eyes with pseudoexfoliation syndrome, high axial myopia, peripheral retinal disease, and multifocal IOL implantation. Toric IOLs and magnet-driven accommodative IOL systems are other potential applications. Generally, POBH holds promise for becoming a routine alternative to standard in-the-bag IOL implantation in the future.     

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.     

Removal of lens epithelial cells to delay anterior capsule-intraocular lens adherence

To test the theory that removing lens epithelial cells at the time of cataract extraction with intraocular lens (IOL) implantation or refractive lens exchange might decrease the rate at which the anterior capsule becomes adherent to the lens optic postoperatively, we performed the technique in approximately 200 eyes that were considered likely to require postoperative IOL exchange. In 4 eyes that had an IOL exchange procedure 6 to 12 weeks after the primary procedure, the anterior capsule was nonadherent or weakly adherent to the lens optic.     

Long-term observation of the refraction with a reversed-optic posterior chamber intraocular lens

A 73-year-old man had phacoemulsification and implantation of a posterior chamber intraocular lens (PC IOL) in both eyes. In the right eye, the optic was unintentionally reversed in the bag. In the left eye, the posterior capsule was ruptured and the IOL haptics were fixated in the ciliary sulcus. The refraction in the sulcus-fixated left eye was stable from 1 month to 4 years. The right eye had a myopic shift at 1 month, with a regression of 1.50 diopters that continued for 2 years. The final IOL position in the right eye was 0.25 mm anterior to the position predicted by the SRK/T formula. It took 2 years for the refraction in the eye with the reversed-optic PC IOL to become stable. A large myopic shift and gradual regression in refraction may stem from a different wound-healing reaction than that of properly fixated IOLs.