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

The lens epithelium as a major determinant in the development, maintenance, and regeneration of the crystalline lens

The crystalline lens is a transparent and refractive biconvex structure formed by lens epithelial cells (LECs) and lens fibers. Lens opacity, also known as cataracts, is the leading cause of blindness in the world. LECs are the principal cells of lens throughout human life, exhibiting different physiological properties and functions. During the embryonic stage, LECs proliferate and differentiate into lens fibers, which form the crystalline lens. Genetics and environment are vital factors that influence normal lens development. During maturation, LECs help maintain lens homeostasis through material transport, synthesis and metabolism as well as mitosis and proliferation. If disturbed, this will result in loss of lens transparency. After cataract surgery, the repair potential of LECs is activated and the structure and transparency of the regenerative tissue depends on postoperative microenvironment. This review summarizes recent research advances on the role of LECs in lens development, homeostasis, and regeneration, with a particular focus on the role of cholesterol synthesis (eg., lanosterol synthase) in lens development and homeostasis maintenance, and how the regenerative potential of LECs can be harnessed to develop surgical strategies and improve the outcomes of cataract surgery (Fig. 1). These new insights suggest that LECs are a major determinant of the physiological and pathological state of the lens. Further studies on their molecular biology will offer possibility to explore new approaches for cataract prevention and treatment.

Safety of the bag-in-the-lens implantation regarding the development of clinically significant pseudophakic cystoid macular edema: A retrospective case series study

PURPOSE

To determine the incidence of clinically significant pseudophakic cystoid macular edema (CSPME) after phacoemulsification using the 'bag-in-the-lens' lens (BIL) implantation technique and to examine the influence of associated risk factors for clinically significant pseudophakic macular edema (CSPME), both ocular and systemic.

METHODS

This retrospective study included 2419 first-operated eyes of 2419 adults who underwent phacoemulsification cataract surgery using the BIL implantation technique between January 2013 and December 2018 in the Antwerp University Hospital, Belgium. The significance of several risk factors (age, gender, previous history, intra- and postoperative complications) was examined by extraction of electronic medical files.

RESULTS

The 3-month incidence of CSPME in the subgroup without risk factors was 0.00% (95% CI: 0.00 -NA). The 3-month incidence of CSPME in the subgroup with risk factors was 0.57% (95% CI 0.22-1.29%). The 3-month incidence of CSPME in the total population of 2419 patients was 0.29% (95% CI: 0.11-0.65%). The risk factors most significantly associated with CSPME included renal insufficiency (hazard ration [HR]: 5.42; 95% CI: 1.69-17.44; P = .014), exudative age-related macular degeneration (HR: 74.50, 95% CI: 25.75-215.6; P < .001) and retinal vein occlusion (HR: 22.48, 95% CI: 4.55-111.02; P = .005).

CONCLUSIONS

In the absence of risk factors, the incidence of CSPME was zero. We can conclude that Primary Posterior Continuous Curvilinear Capsulorhexis (PPCCC) does not increase the risk for CSPME. Non-inferiority of the BIL implantation regarding the development of CSPME, relative to the traditional 'lens-in-the-bag' (LIB) implantation, confirms that BIL is a safe surgical technique. This study also illustrates a previously undescribed risk factor for developing CSPME, namely renal insufficiency.

The importance of the epithelial fibre cell interface to lens regeneration in an in vivo rat model and in a human bag-in-the-lens (BiL) sample

Human lens regeneration and the Bag-in-the-Lens (BIL) surgical treatment for cataract both depend upon lens capsule closure for their success. Our studies suggest that the first three days after surgery are critical to their long-term outcomes. Using a rat model of lens regeneration, we evidenced lens epithelial cell (LEC) proliferation increased some 50 fold in the first day before rapidly declining to rates observed in the germinative zone of the contra-lateral, un-operated lens. Cell multi-layering at the lens equator occurred on days 1 and 2, but then reorganised into two discrete layers by day 3. E- and N-cadherin expression preceded cell polarity being re-established during the first week. Aquaporin 0 (AQP0) was first detected in the elongated cells at the lens equator at day 7. Cells at the capsulotomy site, however, behaved very differently expressing the epithelial mesenchymal transition (EMT) markers fibronectin and alpha-smooth muscle actin (SMA) from day 3 onwards. The physical interaction between the apical surfaces of the anterior and posterior LECs from day 3 after surgery preceded cell elongation. In the human BIL sample fibre cell formation was confirmed by both histological and proteome analyses, but the cellular response is less ordered and variable culminating in Soemmerring's ring (SR) formation and sometimes Elschnig's pearls. This we evidence for lenses from a single patient. No bow region or recognisable epithelial-fibre cell interface (EFI) was evident and consequently the fibre cells were disorganised. We conclude that lens cells require spatial and cellular cues to initiate, sustain and produce an optically functional tissue in addition to capsule integrity and the EFI.

Intraocular Bag-in-the-Lens Exchange: Indications, Outcomes and Complications

PURPOSE

To report the indications, outcomes, and complications regarding the Bag-in-the-lens (BIL) intraocular lens (IOL) exchanges over a period of 13 years in a tertiary ophthalmologic centre.

SETTING

Department of Ophthalmology of the University Hospital of Antwerp (UZA).

DESIGN

Observational retrospective study.

PATIENTS AND METHODS

Between 2003 and 2020, 12 176 patients were operated using the BIL technique. We included adult patients who underwent an intraocular BIL exchange and recorded the demographics, indications, outcomes, and complications.

RESULTS

Fifty-nine eyes of 59 patients who underwent a BIL exchange between 2007 and 2020 were included (0.48%). The mean age was 61.15 ±13.53 years. The mean time between primary surgery and IOL exchange was 25.73 ± 41.88 months. The main indication for explantation was refractive surprise mostly related to the patients' risk factors e.g. preoperative corneal and refractive surgery. The mean preoperative uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA) were 0.36 ± 0.24 and 0.79 ± 0.24 respectively. The postoperative 1 month-UDVA and CDVA were 0.66 ± 0.28 and 0.86 ± 0.19 respectively. The improvement in UDVA was statistically significant (<0.0001). The most common peroperative complication was damage to the anterior hyaloid in 9 eyes (15%), which did not prohibit reimplantation of a secondary BIL.

CONCLUSIONS

BIL to BIL exchange is an viable and successful technique that provides good refractive results with few, manageable complications. Because of the tertiary profile of our centre with referral of complex cases, BIL was our preferred IOL in patients at risk of postoperative refractive surprise.

Precision of bag-in-the-lens intraocular lens power calculation in different age groups of pediatric cataract patients: Report of the Giessen Pediatric Cataract Study Group

PURPOSE

To evaluate the precision of bag-in-the-lens intraocular lens (BIL IOL) power calculation in different age groups of pediatric cataract patients.

SETTINGS

Department of Ophthalmology, Justus-Liebig-University Giessen, University Hospital Giessen and Marburg GmbH, Campus Giessen, Giessen, Germany.

DESIGN

Retrospective nonrandomized consecutive case series.

METHODS

Pediatric patients diagnosed with cataract and operated with BIL IOL implantation were divided into 4 age groups: Group 1 (0 to 3 months), Group 2 (>3 months, <12 months), Group 3 (12 to 36 months), and Group 4 (>36 months to 17 years). BIL IOL power was calculated with the SRK/T formula. The prediction error (PE) was defined as the absolute difference between the preoperative selected target and postoperative achieved refraction. The impact of age at the time of surgery, axial length (AL), keratometry, and corneal astigmatism on PE was analyzed.

RESULTS

The study comprised 87 eyes of 56 pediatric patients. The mean and median PEs for the entire group were 1.79 diopters (D) and 1.23 D, respectively. The mean PE in each age group was: 3.43 D in Group 1, 2.14 D in Group 2, 1.60 D in Group 3, and 1.33 D in Group 4. The mean PE in eyes with ALs shorter than 20 mm was 2.67 D, and 1.44 D in eyes with an AL of 20 mm or longer. The mean PE in eyes with corneal radii less than 7.3 mm was 2.45 D, and 1.66 D in eyes with corneal radii of 7.3 mm or more. In the age and AL subgroups, the PE differences were statistically significant (P < .05).

CONCLUSIONS

The PE was larger in the youngest study group, and it decreased gradually with age and in eyes with ALs shorter than 20 mm. The PE has to be considered during BIL IOL power calculation in children.

Posterior capsule opacification: What's in the bag?

Cataract, a clouding of the lens, is the most common cause of blindness in the world. It has a marked impact on the wellbeing and productivity of individuals and has a major economic impact on healthcare providers. The only means of treating cataract is by surgical intervention. A modern cataract operation generates a capsular bag, which comprises a proportion of the anterior capsule 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 (IOL). 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. Lens epithelial cells, however, remain attached to the anterior capsule, and in response to surgical trauma initiate a wound-healing response that ultimately leads to light scatter and a reduction in visual quality known as posterior capsule opacification (PCO). There are two commonly-described forms of PCO: fibrotic and regenerative. Fibrotic PCO follows classically defined fibrotic processes, namely hyperproliferation, matrix contraction, matrix deposition and epithelial cell trans-differentiation to a myofibroblast phenotype. Regenerative PCO is defined by lens fibre cell differentiation events that give rise to Soemmerring's ring and Elschnig's pearls and becomes evident at a later stage than the fibrotic form. Both fibrotic and regenerative forms of PCO contribute to a reduction in visual quality in patients. This review will highlight the wealth of tools available for PCO research, provide insight into our current knowledge of PCO and discuss putative management of PCO from IOL design to pharmacological interventions.

Incidence of rhegmatogenous retinal detachment after bag-in-the-lens IOL implantation: extended follow-up in a larger cohort of patients

PURPOSE

To report the incidence of rhegmatogenous retinal detachment (RRD) and associated risk factors after cataract surgery using the bag-in-the-lens (BIL) intraocular lens (IOL) implantation technique.

SETTING

Department of Ophthalmology, Antwerp University Hospital, Belgium.

DESIGN

Prospective cohort study.

METHODS

All consecutive BIL IOL surgeries performed between January 2001 and December 2010 were included, with the exclusion of combined procedures and IOL exchanges. The incidence of RRD was reported first in the total cohort, then in a subgroup of patients with 1 year to 5 years of follow-up, and finally in the group remaining after exclusion of all risk factors, except gender. Risk factors associated with RRD were examined using multiple Cox regression analysis with a random intercept.

RESULTS

Rhegmatogenous RD was diagnosed in 36 eyes (1.06%) of 3385 BIL cases, with a mean follow-up of 48.28 ± 40.05 months (range 0 to 195 months). The 2-year cumulative RRD incidence rate was 0.66% (17 cases in 1024 eyes; 0.00% in patients without risk factors). The 5-year cumulative RRD incidence rate was 1.17% (26 cases in 931 eyes; 0.15% without risk factors). Five risk factors were confirmed: male sex, age less than 60 years at the time of surgery, axial length 25.0 mm or greater, a history of contralateral RD, and intraoperative surgical complications.

CONCLUSIONS

The incidence of RRD after BIL IOL implantation is comparable with that of lens-in-the-bag (LIB) implantation. This larger study provided a longer follow-up and suggested that RRD incidence is even lower than that previously reported. This study also confirmed intraoperative surgical complications as an additional risk factor for RRD development, as already described with LIB implantation.

Clinically significant pseudophakic cystoid macular edema after bag-in-the-lens implantation

PURPOSE

To determine the incidence of clinically significant pseudophakic cystoid macular edema (CSPME) after phacoemulsification using the bag-in-the-lens intraocular lens (BIL IOL) implantation technique and to examine the influence of associated risk factors, both ocular and systemic.

SETTING

Monocentric, Antwerp University Hospital, Belgium.

DESIGN

Retrospective.

METHODS

This study included 1 077 first-operated eyes of 1 077 adults who underwent phaco-emulsification cataract surgery using the BIL IOL implantation technique between January 2013 and December 2015.

RESULTS

The 3-month incidence of CSPME in the subgroup without risk factors was 0% (95% CI, 0.0-0.0). The 3-month incidence of CSPME in the subgroup with risk factors was 2.8% (95% CI, 1.3-4.3). The 3-month incidence of CSPME in the total group of 1077 patients was 1.4% (95% CI, 0.6-2.1). The risk factors most significantly associated with CSPME included diabetes (hazard ratio [HR]: 5.37; 95% CI, 1.5-19.3; P = .019), exudative age-related macular degeneration (HR: 121; 95% CI, 36.1-409; P < .001), and macular traction (HR: 6.47; 95% CI, 1.9-22.1; P < .009).

CONCLUSIONS

The incidence of CSPME was zero in eyes without risk factors. The incidence was consistent with previous reports in the literature regarding the lens-in-the-bag IOL implantation technique in eyes with risk factors. This indicates that the BIL IOL implantation technique is a safe procedure and does not confer a higher risk for developing cystoid macular edema after cataract surgery compared with the lens-in-the-bag IOL implantation technique, despite the requirement of a primary posterior continuous curvilinear capsulorhexis.

The human capsular bag model of posterior capsule opacification

Posterior capsule opacification (PCO) is the most common complication following cataract surgery and affects millions of patients. PCO is a consequence of surgical injury promoting a wound-healing response. Following surgery, residual lens epithelial cells grow on acellular regions of the lens capsule, including the central posterior capsule. These cells can undergo fibrotic changes, such that cell transdifferentiation to myofibroblasts, matrix deposition and matrix contraction can occur, which contribute to light scatter and the need for further corrective Nd:YAG laser capsulotomy in many patients. It is therefore of great importance to better understand how PCO develops and determine better approaches to manage the condition. To achieve this, experimental systems are required, and many are available to study PCO. While there may be a number of common features associated with PCO in different species, the mechanisms governing the condition can differ. Consequently, where possible, human systems should be employed. The human capsular bag model was established in a laboratory setting on donor eyes. A capsulorhexis is performed to create an opening in the anterior capsule followed by removal of the lens fibre mass. Residual fibre cells can be removed by irrigation/aspiration and if required, an intraocular lens can be implanted. The capsular bag is isolated from the eye and transferred to a dish for culture. The human capsular bag model has played an important role in understanding the biological processes driving PCO and enables evaluation of surgical approaches, IOLs and putative therapeutic agents to better manage PCO.

Cataract surgeon viewpoints on the need for novel preventative anti-inflammatory and anti-posterior capsular opacification therapies

Purpose: To determine cataract surgeon viewpoints on the efficacy of available therapies/preventatives for two common sequelae of cataract surgery: inflammation and posterior capsular opacification (PCO). Methods: Cataract surgeons practicing worldwide specializing in adult, pediatric and veterinary patients were interviewed between March and August 2018. Results: Ocular inflammation following cataract surgery is treated by either corticosteroids and/or nonsteroidal anti-inflammatories (NSAIDs). Adult and pediatric cataract surgeons are satisfied with current treatments whereas this inflammation is still considered a problem by some in veterinary practice due to its slow resolution. Yttrium-aluminum-garnet (YAG) laser therapy is the PCO treatment of choice for adult cataract surgeons and they are generally pleased with its outcome. However, pediatric cataract surgeons find YAG problematic, especially in patients under 6 years of age, and invasive surgery is often needed to correct PCO/visual axis opacification (VAO). Veterinary ophthalmologists report that YAG is not effective for PCO in animals, especially dogs, due to the density of the fibrotic plaques; 86% of adult and 100% of veterinary and pediatric cataract surgeons surveyed agree that effective anti-PCO therapeutics would improve clinical care. Conclusions: Surgeons treating human patients are pleased with the available treatments for ocular inflammation following cataract surgery, although some veterinary ophthalmologists disagree. The surgeons surveyed agree that PCO/VAO remains an unsolved problem in pediatric and veterinary cataract surgery while the long-term outcome of adult cataract surgery could be improved by additional attention to this issue.

Modified bean-shaped ring segments for suture fixation of the bag-in-the-lens intraocular implant

We describe a surgical technique for secondary stabilization of a bag-in-the-lens intraocular lens (BIL IOL) using 2 modified bean-shaped ring segments in cases of zonular dehiscence associated with pseudophakodonesis. The first modified bean segment is anchored in the sulcus with a suture to the sclera in the area of maximum zonular dehiscence, and the second segment is implanted in the opposite sulcus area. Both segments are placed in the BIL IOL interhaptic groove. The segments stabilize and center the BIL IOL by creating an artificial zonule that provides the necessary extra support for the IOL.

Incidence of rhegmatogenous retinal detachment after bag-in-the-lens intraocular lens implantation

PURPOSE

To determine the incidence of rhegmatogenous retinal detachment (RRD) and associated risk factors after phacoemulsification and bag-in-the-lens intraocular lens (IOL) implantation.

SETTING

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

DESIGN

Prospective cohort study.

METHODS

All consecutive bag-in-the-lens IOL implantations performed between January 2001 and December 2007 were included, with the exception of combined procedures and IOL exchanges. The retinal detachment (RD) incidence was studied in the total cohort, in a subgroup of patients with 1 to 5 years of follow-up, and finally in the group remaining after exclusion of all risk factors except gender.

RESULTS

RD after bag-in-the-lens IOL implantation in 1323 eyes with an average follow-up of 44.75 months (range 0 to 152 months) was found in 19 eyes (1.44%). The 1-year RD incidence was 0.49% (5 RD cases in 1024 eyes) (0.00% in patients without risk factors). The 2-year cumulative RD incidence was 0.84% (9 RD cases in 931 eyes; 0.15% without risk factors). Four clinically significant risk factors were confirmed: male gender, young age at time of surgery (<60 years), axial myopia (axial length ≥25 mm), and history of contralateral RD in the total cohort.

CONCLUSION

The RRD incidence following bag-in-the-lens IOL implantation was comparable to that seen after lens-in-the-bag (LIB) implantation. The wide variation in study design in the literature precludes direct comparison, so there is a need for standardization in evaluating RRD incidence after cataract surgery. Future prospective studies should consider patients with and without risk factors (except gender) separately.

FINANCIAL DISCLOSURE

Prof. dr. M.J. Tassignon has intellectual property rights to the bag-in-the-lens intraocular lens (U.S. patent 6 027 531; EU patent 009406794; PCT/120268), which is licensed to Morcher GmbH, Stuttgart, Germany.

Experimental models for posterior capsule opacification research

Millions of people worldwide are blinded due to cataract formation. At present the only means of treating a cataract is through surgical intervention. A modern cataract operation involves the creation of an opening in the anterior lens capsule to allow access to the fibre cells, which are then removed. This leaves in place a capsular bag that comprises the remaining anterior capsule and the entire posterior capsule. In most cases, an intraocular lens is implanted into the capsular bag during surgery. This procedure initially generates good visual restoration, but unfortunately, residual lens epithelial cells undergo a wound-healing response invoked by surgery, which in time commonly results in a secondary loss of vision. This condition is known as posterior capsule opacification (PCO) and exhibits classical features of fibrosis, including hyperproliferation, migration, matrix deposition, matrix contraction and transdifferentiation into myofibroblasts. These changes alone can cause visual deterioration, but in a significant number of cases, fibre differentiation is also observed, which gives rise to Soemmering's ring and Elschnig's pearl formation. Elucidating the regulatory factors that govern these events is fundamental in the drive to develop future strategies to prevent or delay visual deterioration resulting from PCO. A range of experimental platforms are available for the study of PCO that range from in vivo animal models to in vitro human cell and tissue culture models. In the current review, we will highlight some of the experimental models used in PCO research and provide examples of key findings that have resulted from these approaches.

A randomized intraindividual comparison of the accommodative performance of the bag-in-the-lens intraocular lens in presbyopic eyes

PURPOSE

To compare the accommodative performance of the Morcher BioComFold Type 89A bag-in-the-lens intraocular lens (IOL) with a conventional in-the-bag control IOL in presbyopic eyes.

DESIGN

Prospective, randomized clinical trial with intraindividual comparison.

METHODS

SETTING

Department of Ophthalmology, St. Thomas' Hospital, London, United Kingdom.

STUDY POPULATION

Fifty-two eyes of 26 patients with bilateral age-related cataracts.

INTERVENTION

Phacoemulsification cataract extraction with implantation of a bag-in-the-Lens and a control IOL, the Alcon AcrySof SA60AT (Alcon Laboratories, Fort Worth, Texas, USA), randomized to either eye.

MAIN OUTCOME MEASURES

Axial IOL shift stimulated by physiologic (near visual effort) and pharmacologic (pilocarpine and cyclopentolate) accommodative stimulation was measured objectively with partial coherence interferometry. Other outcome measures were objective and subjective accommodation, logarithm of the minimal angle of resolution distance-corrected near visual acuity, and defocus curves.

RESULTS

Three months after surgery, axial IOL shift stimulated by near visual effort measured -5.9 ± 10.3 μm in bag-in-the-lens eyes versus -8.4 ± 12.8 μm in control eyes (P = .37), that stimulated by pilocarpine measured 20.2 ± 165.6 μm versus 50.4 ± 164.4 μm (P = .36), and that stimulated by cyclopentolate measured -65.8 ± 64.3 μm versus -54.0 ± 37.5 μm (P = .34), respectively (n = 25). Objective accommodation measured 0.03 ± 0.18 diopters (D) in bag-in-the-lens eyes versus 0.08 ± 0.21 D in control eyes (P = .40), whereas subjective accommodation measured 2.48 ± 0.72 D versus 2.45 ± 0.80 D (P = .75), respectively. Distance-corrected near visual acuity and defocus curves showed no difference between IOLs.

CONCLUSIONS

The bag-in-the-lens IOL demonstrated negligible axial shift and objective accommodation with physiologic near visual stimulation. The IOL shift demonstrated with pilocarpine also was clinically insignificant. The bag-in-the-lens IOL showed no accommodative or near visual advantage over a conventional in-the-bag IOL, despite its unique capsular fixation method. This provides further evidence that the focus-shift principle fails to produce clinically significant IOL movement.

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.

Control of inflammation and prophylaxis of endophthalmitis after cataract surgery: a multicenter study

PURPOSE

To compare two different postcataract surgery antibiotic/steroid therapeutic combinations, for clinical results as well as patient satisfaction.

METHODS

Prospective randomized clinical trial of patients with bilateral operative cataract. Postoperatively, for 15 days one eye was randomly assigned to therapy with the combination chloramphenicol 0.25%-betamethasone 0.13% gel three times a day (Group 1) and the other to the combination tobramycin 0.3%-dexamethasone 0.1% eyedrops four times a day (Group 2).

RESULTS

A total of 142 patients (284 eyes) completed the study. The authors could not detect any significant difference between Group 1 and Group 2 concerning preoperative evaluation, surgical procedure, and complications. Pertaining to the two therapeutic regimens, efficacy, side effects, and clinical findings such as uncorrected visual acuity, intraocular pressure, edema or hyperemia of eyelids and/or conjunctiva, conjunctival and/or ciliary vessels congestion, decreased corneal transparency, corneal edema, Descemet folds, anterior chamber Tyndall and depth, and posterior synechiae were also comparable. Postoperative subjective pain and dry eye sensation were comparable between the two groups, while the gel preparation elicited a significantly more pleasant sensation in the patients (p=0.04).

CONCLUSIONS

The motivation for use of a gel is to prolong the permanence of associated drugs on the ocular surface, increasing potency and decreasing concentration of the drug and rate of administration. This in order to improve compliance and decrease potential side effects. Chloramphenicol 0.25%-betamethasone 0.13% gel combination proved to have comparable efficacy, tolerance, and better acceptance by the patients than an aqueous tobramycin 0.3%-dexamethasone 0.1% preparation.

Advances in the management of congenital and infantile cataract

Congenital and infantile cataracts produce deprivation amblyopia and can thus cause lifelong visual impairment. Successful management is dependent on early diagnosis and referral for surgery when indicated. Accurate optical rehabilitation and postoperative supervision are essential.The timing of surgery and its relationship to the duration of deprivation is important. Unilateral congenital cataract surgery within 6 weeks of birth produces the best outcomes. The equivalent 'latent' period for bilateral visual deprivation may be longer at around 10 weeks. Visual deprivation has a significant impact on the development of fixation stability. Major form deprivation, even after early surgery, leads to nystagmus. This is mostly manifest latent nystagmus (MLN). The latent period for fixation stability may be as short as 3 weeks. Preoperative congenital nystagmus (CN) can convert to more benign MLN after surgery. Infantile IOL implantation is becoming increasingly accepted. A satisfactory long-term refractive result requires that allowance be made for childhood axial growth and myopic shift. In a series of 25 infants (33 eyes) implanted before 12 months of age, the mean myopic shift at 12 months was 4.83 D. This increased to 5.3 D in infants implanted before 10 weeks. The initial desired refractive outcome following IOL implantation is thus hypermetropia, with the degree dependent on the age of the child. Glaucoma or ocular hypertension is a common complication following paediatric cataract surgery. Microphthalmia and surgery in early infancy are risk factors. Tonometry results may be influenced by the increased corneal thickness seen in aphakic and pseudophakic children. The long-term prognosis of eyes with aphakic glaucoma is not necessarily poor but intraocular pressure control may require three or more medications. Surgical intervention appears to be necessary in over a quarter of eyes. Posterior capsule opacification (PCO) is common in infants undergoing primary lens implantation. Primary capsulotomy and anterior vitrectomy reduce the risk of PCO. In the absence of anterior vitrectomy, primary posterior capsulotomy does not prevent visual axis opacification. Further developments will continue to be driven by clinical research. The prevention of capsule opacification and cellular proliferation may in future be achieved by the use of devices to specifically target epithelial cells at surgery.

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.

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.

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.

Lens cell targetting for gene therapy of prevention of posterior capsule opacification

Posterior capsule opacification is the main complication of cataract surgery. Using adenovirus-mediated gene transfer, we recently reported that it was feasible to prevent PCO by overexpressing pro-apoptotic molecules such as pro-caspase 3 or Bax in the residual lens epithelial cells post-cataract surgery. However, this approach is feasible only if gene transfer can be restricted to the residual cells responsible for PCO. Initially, we tested an adenovirus (human serotype 5, HAd5), a lentivirus (HIV) and an oncoretrovirus (MLV) vector for the their in vivo transduction efficiency of rabbit lens cells. We found that HAd5 vectors were the most efficient (>90% of the cells could be transduced). Six potential lens-specific promoters were then cloned into HAd5 vectors and assayed for their ability to target expression to a specific population of cells, using in vitro, ex vivo and in vivo rabbit tissues and human lens capsular bags. We found that the LEP503, MIP and Filensin promoters induced strong lens-specific expression of a reporter gene, in human lens cells. Following this ex vivo assay, we showed in a rabbit PCO model that gene transfer could be spatially restricted to the capsular bag by confining the vector with Matrigel. Our combined approach using a lens-specific promoter and a biocompatible gel should render feasible a novel therapeutic strategy for PCO that targets the remaining lens cells.