Bag-in-the-lens implantation of intraocular lenses

Interventions for preventing posterior capsule opacification

BACKGROUND

Posterior capsule opacification (PCO) remains the most common long-term complication after cataract surgery. It can be treated by Nd:YAG laser capsulotomy, however this may lead to other complications and laser treatment is not available in large parts of the developing world. Therefore, many studies try to find factors influencing the development of PCO.

OBJECTIVES

To summarise the effects of different interventions to inhibit PCO. These include modifications of surgical technique and intraocular lens (IOL) design, implantation of additional devices and pharmacological interventions.

SEARCH STRATEGY

We searched CENTRAL, MEDLINE, EMBASE, LILACS in March 2009 and reference lists of identified trial reports.

SELECTION CRITERIA

We included only prospective, randomised and controlled trials with a follow-up time of at least 12 months. Interventions included modifications in surgical technique explicitly to inhibit PCO, modifications in IOL design (material and geometry), implantation of additional devices and pharmacological therapy compared to each other, placebo or standard treatment.

DATA COLLECTION AND ANALYSIS

We extracted data and entered it into RevMan. We compared visual acuity data, PCO scores and YAG capsulotomy rates and performed a meta-analysis when possible.

MAIN RESULTS

Sixty six studies were included in the review. The review was divided into three parts. 1. Influence of IOL optic material on the development of PCO. There was no significant difference in PCO development between the different IOL materials (PMMA, hydrogel, hydrophobic acrylic, silicone) although hydrogel IOLs tend to have higher PCO scores and silicone IOLs lower PCO scores than the other materials. 2. Influence of IOL optic design on the development of PCO. There was a significantly lower PCO score (-8.65 (-10.72 to -6.59), scale 0 to 100) and YAG rate (0.19 (0.11 to 0.35)) in sharp edged than in round edged IOLs, however not between 1-piece and 3-piece IOLs. 3. Influence of surgical technique and drugs on the development of PCO. There was no significant difference between different types of intraoperative/postoperative anti-inflammatory treatment except for treatment with an immunotoxin (MDX-A) which led to a significantly lower PCO rate.

AUTHORS' CONCLUSIONS

Due to the highly significant difference between round and sharp edged IOL optics, IOLs with sharp (posterior) optic edges should be preferred. There is no clear difference between optic materials. The choice of postoperative anti-inflammatory treatment does not seem to influence PCO development.

Posterior capsule opacification

Posterior Capsule Opacification (PCO) is the most common complication of cataract surgery. At present the only means of treating cataract is by surgical intervention, and this initially restores high visual quality. Unfortunately, PCO develops in a significant proportion of patients to such an extent that a secondary loss of vision occurs. A modern cataract operation generates a capsular bag, which comprises a proportion of the anterior and the entire posterior capsule. The bag remains in situ, partitions the aqueous and vitreous humours, and in the majority of cases, houses an intraocular lens. The production of a capsular bag following surgery permits a free passage of light along the visual axis through the transparent intraocular lens and thin acellular posterior capsule. However, on the remaining anterior capsule, lens epithelial cells stubbornly reside despite enduring the rigours of surgical trauma. This resilient group of cells then begin to re-colonise the denuded regions of the anterior capsule, encroach onto the intraocular lens surface, occupy regions of the outer anterior capsule and most importantly of all begin to colonise the previously cell-free posterior capsule. Cells continue to divide, begin to cover the posterior capsule and can ultimately encroach on the visual axis resulting in changes to the matrix and cell organization that can give rise to light scatter. This review will describe the biological mechanisms driving PCO progression and discuss the influence of IOL design, surgical techniques and putative drug therapies in regulating the rate and severity of PCO.

Intraocular pressure rise after primary posterior continuous curvilinear capsulorhexis with a fixed dorzolamide–timolol combination

PURPOSE

To assess the safety, in terms of the intraocular pressure (IOP), of cataract surgery with primary posterior continuous curvilinear capsulorhexis (PPCCC) and a postoperative dose of a fixed dorzolamide-timolol combination and evaluate the effect of intraocular lens (IOL) haptic angulation.

SETTING

Department of Ophthalmology, Medical University of Vienna, Vienna, Austria.

METHODS

In this prospective randomized double-masked bilateral study, 88 eyes of 44 consecutive patients with age-related cataract were included in an intraindividual comparison study. All patients had standardized cataract surgery with PPCCC and IOL implantation in the capsular bag followed by a postoperative dose of a fixed dorzolamide-timolol combination. Patients were randomly assigned to receive an ACR6D SE IOL (Laboratoires Cornéal) in 1 eye and a Centerflex (C-flex) 570C IOL (Rayner Surgical GmbH) in the contralateral eye. The IOP was measured at baseline and postoperatively at 6 and 24 hours as well as 1 week.

RESULTS

Intraindividual comparison showed statistically significantly higher IOP measurements in the C-flex 570C nonangulated IOL group than in the ACR6D SE angulated IOL group at 24 hours (P = .003) and 1 week (P = .043). The highest IOP spikes (34 mm Hg) were at 6 hours in 2 eyes with a C-flex 570C IOL. The ACR6D SE group had statistically significant changes in IOP between preoperative and all postoperative time points. In the C-flex 570C group, the only statistically significant change in IOP was between preoperatively and 6 hours postoperatively.

CONCLUSIONS

Cataract surgery with PPCCC was safe in terms of the postoperative IOP course. Haptic angulation slightly decreased the overall IOP rise and the incidence of IOP rises above 30 mm Hg.

Interventions for preventing posterior capsule opacification

BACKGROUND

Posterior capsule opacification (PCO) remains the most common long-term complication after cataract surgery. It can be treated by Nd:YAG laser capsulotomy, however, this may lead to other complications and laser treatment is not available in large parts of the developing world. Therefore, many studies try to find factors influencing the development of PCO.

OBJECTIVES

To summarise the effects of different interventions to inhibit PCO. These include modifications of surgical technique and intraocular lens (IOL) design, implantation of additional devices and pharmacological interventions.

SEARCH STRATEGY

We searched CENTRAL, MEDLINE, EMBASE, LILACS in January 2007 and reference lists of identified trial reports.

SELECTION CRITERIA

We included only prospective, randomised and controlled trials with a follow-up time of at least 12 months. Interventions included modifications in surgical technique explicitly to inhibit PCO, modifications in IOL design (material and geometry), implantation of additional devices, and pharmacological therapy, compared to each other, placebo or standard treatment.

DATA COLLECTION AND ANALYSIS

Data were extracted and entered into Review Manager. Visual acuity data, PCO score and YAG capsulotomy rates were compared and a meta-analysis was performed when possible.

MAIN RESULTS

Fifty three studies were included in the review. The review was divided into three parts. (1) Influence of IOL optic material on the development of PCO. Compared to other materials, the meta-analysis of the included studies showed a significantly higher PCO score (overall effect: 12.39 (95% confidence interval: 9.82 to 14.95), scale 0 to 100) and YAG rate (odds ratio: 8.37 (3.74 to 20.36)) only in hydrogel IOLs. (2) Influence of IOL optic design on the development of PCO. There was a significantly lower PCO score (-8.65 (-10.72 to -6.59), scale 0 to 100) and YAG rate (0.19 (0.11 to 0.35)) in sharp edged than in round edged IOLs, however, not between 1-piece and 3-piece IOLs. (3) Influence of surgical technique and drugs on the development of PCO. There was no significant difference between different types of intra-/postoperative anti-inflammatory treatment except for treatment with an immunotoxin (MDX-A) leading to a significantly lower PCO rate.

AUTHORS' CONCLUSIONS

Due to the highly significant difference between round and sharp edge IOL optics, IOLs with sharp (posterior) optic edges should be preferred. There is no clear difference between optic materials, except for hydrogel IOLs, that showed more PCO than the other materials. The choice of postoperative anti-inflammatory treatment does not seem to influence PCO development.

Intraocular lens centration and visual outcomes after bag-in-the-lens implantation

PURPOSE

To examine the centration and visual outcomes after cataract surgery using the bag-in-the-lens (BIL) implantation technique.

SETTING

University Hospital Antwerp, Department of Ophthalmology, Edegem, Belgium.

METHODS

This study comprised 180 eyes of 125 patients who had cataract surgery with implantation of the BIL intraocular lens (IOL) between March 2002 and September 2005. Postoperative data at 5 weeks, 6 months, and 1 year were evaluated. The geometric center of the IOL, measured on a red reflex slitlamp photograph, was compared with the geometric center of the pupil and the limbus.

RESULTS

The mean decentration compared with the limbus was 0.304 mm+/-0.17 (SD) at a mean angle of -24.9+/-113.3 degrees. Compared with the dilated pupil, the mean deviation was 0.256+/-0.15 mm at a mean angle of -5.2+/-119.0 degrees. The amount of decentration was stable during the postoperative follow-up period. There was no correlation between the amount of decentration and the visual outcomes (pupil: r=-0.07, P=.494; limbus: r=0.11, P=.304).

CONCLUSIONS

Surgeon-controlled BIL centration was predictable 5 weeks and unchanged 6 months and 1 year postoperatively. It can therefore be concluded that capsular bag healing has no influence on BIL IOL centration over time.

Bag-in-the-lens intraocular lens implantation in the pediatric eye

PURPOSE

To study the efficacy, safety, and feasibility of implantation of a bag-in-the-lens intraocular lens (IOL) in children and babies.

SETTING

Departments of Ophthalmology, University Hospital, Antwerp, Belgium, and the University Hospital, Ljubljana, Slovenia, and a private ophthalmology practice, Oudenaarde, Belgium.

METHODS

Thirty-four eyes of 22 children had implantation of a bag-in-the-lens IOL. The ages ranged from 2 months to 14 years. Congenital cataract was present in 26 eyes, and persistent fetal vasculature (PFV) was concomitantly present in 4 eyes. Fifteen patients had bilateral cataract, and 6 had unilateral cataract.

RESULTS

In 3 eyes, the IOL could not be properly implanted. In these cases, secondary intervention was necessary because of early posterior capsule opacification. The mean postoperative follow-up was 17.45 months +/- 17.12 (SD) (range 4 to 68 months). None of the children except those presenting with PFV had anterior vitrectomy during surgery. The optical axis remained clear during the follow-up in all patients who had successful IOL implantation.

CONCLUSIONS

The bag-in-the-lens implantation technique in children and babies was safe and kept the visual axis clear after cataract surgery. In the near future, 4.0 or 4.5 mm IOLs will be available that may improve the success rate of IOL implantation in the small eyes of babies.

Cumulative neodymium:YAG laser rates after bag-in-the-lens and lens-in-the-bag intraocular lens implantation

PURPOSE

To study the cumulative neodymium:YAG (Nd:YAG) laser rate after bag-in-the-lens implantation (Morcher 89A) and lens-in-the-bag implantation (Morcher 92S) of 2 intraocular lenses (IOLs) of the same biomaterial.

SETTING

Department of Ophthalmology, University Hospital of Antwerp, Edegem, Belgium.

METHODS

This study comprised 100 eyes of 87 patients who had the bag-in-the-lens IOL implantation between January 2000 and August 2004. The postoperative follow-up ranged between 17 and 72 months. One hundred eyes of 94 patients of the same age and with the same follow-up period received the lens-in-the-bag IOL. The cumulative Nd:YAG laser frequency rates in both groups were calculated, and the cumulative incidence rates were defined by Kaplan-Meier survival analysis.

RESULTS

No Nd:YAG laser capsulotomy was performed in eyes having bag-in-the-lens IOL implantation. A laser capsulotomy was performed in 20 eyes having lens-in-the-bag IOL implantation; the cumulative frequency in this group was 2% at 1 year and 20% at 71 months, with a plateau beginning at 42 months. The cumulative incidence rate of Nd:YAG posterior capsulotomy was approximately 2% at 1 year, increasing to approximately 28% at 42 months.

CONCLUSIONS

The cumulative Nd:YAG laser rate after bag-in-the-lens implantation was zero. A zero rate has not been reported with lens-in-the-bag implantation of an IOL of the same biomaterial or of other biomaterials, as published in the literature. Thus, it can be concluded that the bag-in-the-lens implantation technique has 100% effectiveness against posterior capsule opacification.

One-year follow-up of bag-in-the-lens intraocular lens implantation in 60 eyes

PURPOSE

To report the feasibility and clinical results of implanting a bag-in-the-lens intraocular lens (IOL) designed to prevent posterior capsule opacification after cataract surgery.

SETTING

Departments of Ophthalmology, University of Antwerp, Antwerp, Belgium, and University of Munich, Munich, Germany.

METHODS

This prospective study comprised 63 eyes (55 patients; 7 children, 48 adults) scheduled for cataract surgery and bag-in-the-lens IOL implantation. A posterior curvilinear capsulorhexis the same size as the anterior capsulorhexis was created for IOL insertion. After surgery, lens epithelial cell (LEC) proliferation was documented every 6 months with a minimum follow-up of 12 months.

RESULTS

Sixty of 63 eyes (95%) had implantation of the bag-in-the-lens IOL. Conversion to a conventional IOL was necessary in 2 cases. In 1 eye, postoperative luxation of the IOL into the vitreous occurred as a result of an oversized anterior and posterior capsulorhexis. Three eyes had early postoperative iris incarceration in the lens groove that required surgery. No LEC proliferation on the optic occurred during a mean follow-up of 22.7 months (range 12 to 64 months); LEC proliferation was confined to the peripheral capsular bag.

CONCLUSION

Lens epithelial cell proliferation was mild and confined to the periphery of the capsular bag during follow-up, and the bag-in-the-lens IOL optic remained clear.

Routine posterior optic buttonholing for eradication of posterior capsule opacification in adults: report of 500 consecutive cases

PURPOSE

To study the efficacy of posterior optic buttonholing (POBH) through a primary posterior capsulorhexis (PPCCC) to preserve full capsular transparency, and its potential as a routine alternative to standard in-the-bag implantation of sharp-edged optic intraocular lenses (IOLs).

SETTING

Department of Ophthalmology, Medical University of Vienna, Vienna, Austria.

METHODS

After standard cataract removal, a PPCCC 4.0 to 5.0 mm in diameter was performed and the optic of a 3-piece IOL buttonholed posteriorly. One third of the eyes additionally had extensive anterior capsule polishing. All surgeries were performed under topical anesthesia.

RESULTS

The first 500 consecutive surgeries were evaluated. In 11 eyes, POBH was not performed as planned. In 4 cases, anterior capsulorhexis fixation of the optic was used as an alternative. In the early series, vitreous entanglement was seen in 5 eyes, of which 1 case prompted translimbal anterior vitrectomy. No case of cystoid macula edema was observed. One case of peripheral retinal detachment in a highly-myopic eye 4 months postoperatively appeared to be unrelated to the surgery. All lenses were well-centered without tilt, and both capsule leaves remained clear especially after additional polishing.

CONCLUSION

Posterior optic buttonholing precludes lens epithelial cells from accessing the retrolental space. The sandwiched posterior capsule blocks optic contact and thus fibrosis of the anterior capsule. Posterior optic buttonholing avoids after-cataract independent of optic edge design. Anterior capsule polishing adds to its efficacy by excluding any residual fibrosis. Surgery under topical anesthesia was well-controlled and safe. Posterior optic buttonholing may become a routine alternative to standard in-the-bag IOL implantation when supported by a longer follow-up.

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.

Ring-shaped caliper for better anterior capsulorhexis sizing and centration

We describe a new type of caliper to optimize the size, shape, and centration of the capsulorhexis during intraocular lens (IOL) surgery. This flexible, ring-shaped tool is positioned on the anterior capsule surface, where it is kept in place by an ophthalmic viscosurgical device. When in place, the caliper provides an ideal guide for the surgeon to follow and facilitates optimal capsulorhexis shape and centration.

Cataracts in children

Bilateral congenital cataract is the most common cause of treatable childhood blindness. Nuclear cataract is usually present at birth and is nonprogressive, whereas lamellar cataract usually develops later and is progressive. Surgery must be performed promptly in cases with dense congenital cataract; if nystagmus has developed, the amblyopia is irreversible. A treatment regimen based on surgery within 2 months of birth combined with prompt optical correction of the aphakia and aggressive occlusion therapy with frequent follow-up has been successful in unilateral and bilateral cases. Both anterior and posterior capsulorhexes are performed in most children. Intraocular lens implantation can be performed safely in children older than 1 year. Anterior dry vitrectomy is recommended in preschool children to avoid after-cataract. Opacification of the visual axis is the most common complication of cataract surgery in children. Secondary glaucoma is the most sight-threatening complication and is common if surgery is performed early. Life-long follow-up is essential in these cases.

Effect of bag-in-the-lens implantation on posterior capsule opacification in human donor eyes and rabbit eyes

PURPOSE

To evaluate bag-in-the-lens implantation by studying the feasibility of implanting a new type of intraocular lens (IOL) and the occurrence of posterior capsule opacification (PCO) in human postmortem eyes and in eyes of living rabbits.

SETTING

Department of Ophthalmology, University of Antwerp, Belgium, and Netherlands Research Institute of Amsterdam, Amsterdam, The Netherlands.

METHODS

The IOL was implanted in 10 postmortem human donor eyes (in vitro study) and in 17 eyes of 10 rabbits (in vivo study). The postmortem capsular bags were cultured for 4 to 6 weeks, and the rabbits were killed 1 to 5 months after implantation. All capsular bags with the bag-in-the-lens were examined by light microscopy and scanning electron microscopy.

RESULTS

The IOL design was highly effective in restricting lens epithelial cell (LEC) proliferation in the remaining lens bag in human donor eyes and in rabbit eyes. In eyes in which the capsules were not positioned well within the groove of the IOL, LEC proliferation and PCO occurred.

CONCLUSION

Bag-in-the-lens implantation was highly effective in preventing PCO in vitro and in vivo provided the anterior and posterior capsules were secured properly in the peripheral groove of the IOL.