Posterior capsular opacification with hydrogel, polymethylmethacrylate, and silicone intraocular lenses: two-year results of a randomized prospective trial

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.

An In Vitro Human Lens Capsular Bag Model Adopting a Graded Culture Regime to Assess Putative Impact of IOLs on PCO Formation

Purpose

To develop a culture regime for the in vitro human lens capsular bag model that better reflects clinical events following cataract surgery and to use this refined model to evaluate the putative impact of IOLs on PCO formation.

Methods

Capsulorhexis and lens extraction were performed on human donor eyes to generate capsular bags attached to the ciliary body by the zonules. Preparations were secured by pinning the ciliary body to a silicone ring and maintaining in 6 mL serum-free EMEM for 28 days or in a graded culture system (days 1-3, 5% human serum and 10 ng/mL TGFβ2; days 4-7, 2% human serum and 1 ng/mL TGFβ2; days 8-14, 1% human serum and 0.1 ng/mL TGFβ2; days 15-28, serum-free EMEM), which better mimics clinical changes. Preparations were monitored with phase-contrast and modified-dark-field microscopy. Cell coverage and light scatter were quantified using image analysis software. The transdifferentiation marker, α-SMA and matrix component, fibronectin were assessed by immunocytochemistry. To assess IOLs in the model, Alcon Acrysof or Hoya Vivinex IOLs were implanted in match-paired capsular bags.

Results

Match-paired experiments showed that graded culture enhanced growth, facilitated matrix contraction, increased transdifferentiation, and promoted matrix deposition relative to serum-free culture. The graded culture protocol was applied to match-paired bags implanted with a Hoya Vivinex or an Alcon Acrysof IOL. The Vivinex demonstrated a lag in growth across the posterior capsule. However, by day 28, coverage was similar, but light-scatter was greater with Acrysof implanted. Cell growth on the Acrysof IOL anterior surface was significantly greater than Vivinex.

Conclusions

The graded culture human capsular bag model serves as an excellent system to evaluate and develop intraocular lenses. The Hoya Vivinex IOL showed an overall better level of performance against postsurgical wound healing and PCO than the Alcon Acrysof using this model.

Efficacy and safety of primary posterior capsulotomy in combined phaco-vitrectomy in rhegmatogenous retinal detachment

OBJECTIVE

To evaluate the efficacy and safety of posterior capsulotomy by analyzing the long-term visual outcomes in patients with rhegmatogenous retinal detachment (RD), who underwent combined phaco-vitrectomy with or without primary posterior capsulotomy.

METHODS

A retrospective longitudinal cohort analysis was performed by using data of rhegmatogenous RD patients undergoing combined phaco-vitrectomy. Patients were divided into two groups; Group A (68 eyes of 68 patients) with capsulotomy, and Group B (39 eyes of 39 patients) without capsulotomy. We reviewed the best-corrected visual acuity (BCVA), incidence of posterior capsule opacification (PCO), clinical features at the diagnosis of rhegmatogenous RD, and intraoperative or postoperative complications following posterior capsulotomy.

RESULTS

The modified BCVA measured by the logarithm of the minimum angle of resolution at initial diagnosis and 3, 6, and 12 months after surgery was 0.67 in Group A versus 0.85 in Group B (p = 0.258), 0.40 in Group A versus 0.50 in Group B (p = 0.309), 0.27 in Group A versus 0.45 in Group B (p = 0.055), and 0.21 in Group A versus 0.47 in Group B (p = 0.014), respectively. In subgroup with macula-on RRD, Group A exhibited better visual outcomes compared to Group B at 6(0.17 versus 0.40 [p = 0.037]) and at 12 months(0.14 versus 0.39 [p = 0.030]). The incidence of PCO in Group B was higher than Group A(28.2% versus 4.4% (p < 0.001)). There were no complications associated with posterior capsulotomy.

CONCLUSIONS

A primary posterior capsulotomy during combined phaco-vitrectomy using a 23-gauge vitreous cutter was a safe and effective surgical procedure in patients with RRD patients for preventing postoperative intraocular lens-related PCO.

Comparing capsular bag performance of a hydrophilic and a hydrophobic intraocular lens: A randomised two-centre study

Purpose:

To evaluate the capsular bag performance and posterior capsule opacification development of two intraocular lenses differing in material and design.

Methods:

This study included patients who were scheduled for cataract surgery and compared a hydrophilic intraocular lens (Super flex® intraocular lens; Rayner Surgical, Worthing, UK) with a hydrophobic intraocular lens (AcrySof® SA60AT; Alcon, Fort Worth, TX, USA). Follow-ups were performed 1 month and 2 years after cataract surgery, including a slit lamp examination and retroillumination images.

Results:

In total, 80 eyes of 80 patients were recruited. At the 1-month follow-up, 6 of 39 cases had a gap between the posterior lens capsule and intraocular lens (1 case in the hydrophilic intraocular lens group and 5 cases in the hydrophobic intraocular lens group; p = 0.348). Objective and subjective posterior capsule opacification scoring showed no statistically significant difference between both groups (p = 0.123).

Conclusion:

Both intraocular lens showed a good capsular bag performance and a relatively low posterior capsule opacification development within the first 2 years after surgery.

The Type II Aachen-Keratoprosthesis in Humans: Case Report of the First Prolonged Application

Purpose

To improve the prognosis of corneal grafts in silicone-oil filled eyes of patients with severe ocular trauma by a prolonged application of the Type II Aachen-Keratoprosthesis (KPro). This application endeavors to improve post-keratoplasty prognosis by avoiding corneal endothelial dystrophy in the aphakic eye due to contact with silicone oil.

Patient and Procedures

The Aachen-Keratoprosthesis’ haptic was modified to allow tight contact with cells. The Type II Aachen-Keratoprosthesis was then implanted in an 18-year-old male, with previous management of bilateral corneal rupture. Rather than utilize the device as a temporary intraoperative tool, we extended the device's lifespan in the eye.

Main Findings

Following implantation, the patient could see hand movements up to 0.1 with best correction. After 8 weeks, vision decreased and a retroprosthetic membrane proliferated. Upon conjunctival retraction, 3 months after the initial surgery, we excised the prosthesis and performed a re-vitrectomy and corneal grafting. The silicone oil was removed. After eighteen postoperative months, the graft remained clear, the retina was completely attached, and the vision was stable: 0.1 best corrected.

Conclusion

This case reports the prolonged implantation and prospect of the Type II Aachen-Keratoprosthesis to be utilized as a permanent device to restore vision in the near future.

Adhesion of the posterior capsule to different intraocular lenses following cataract surgery

PURPOSE

To investigate the prevalence and morphologic and clinical features of posterior capsule-optic inadhesion following cataract surgery.

METHODS

In this prospective cohort study, we examined 518 consecutive patients who had undergone uneventful phacoemulsification and posterior chamber intraocular lens (IOL) implantation. They were assigned into five groups based on the type of IOL used: MC X11 ASP, Rayner 920H A, ZCB00, SN60WF and KS-3Ai. Routine ophthalmic examinations were performed. Patients were followed up at 1 day, 1 week, and 1 and 2 months postsurgery. Anterior segment photography, Scheimpflug imaging and KR-1W aberrometry were conducted after the patients' pupils were dilated.

RESULTS

The overall rate of posterior capsule-optic inadhesion on the first day after surgery was 215/518 (41.5%), and it decreased to 37/518 (7.1%) at 2 months postsurgery. Posterior capsule-optic inadhesion can be morphologically classified into five types with three outcomes, of which gradual absorption of the accumulated fluid predominated for all IOLs. The clinical characteristics of patients with inadhesion varied with IOL type. Notably, visual quality data (Strehl ratios and modulation transfer function) were poorer in patients with posterior capsule-optic inadhesion, especially in those with irregular forms of suspension. Four cases of capsular contraction syndrome were identified among the patients with inadhesion.

CONCLUSIONS

Posterior capsule-optic inadhesion is a prevalent capsule-IOL interaction following cataract surgery. Although the accumulated fluid is absorbed in the majority of patients, its adverse effects on visual outcomes, especially visual quality in the operated eye(s), must not be underestimated in patients with persistent inadhesion.

Prevention of posterior capsular opacification

Posterior capsular opacification (PCO) is a common complication of cataract surgery. The development of PCO is due to a combination of the processes of proliferation, migration, and transdifferentiation of residual lens epithelial cells (LECs) on the lens capsule. In the past decades, various forms of PCO prevention have been examined, including adjustments of techniques and intraocular lens materials, pharmacological treatments, and prevention by interfering with biological processes in LECs. The only method so far that seems effective is the implantation of an intraocular lens with sharp edged optics to mechanically prevent PCO formation. In this review, current knowledge of the prevention of PCO will be described. We illustrate the biological pathways underlying PCO formation and the various approaches to interfere with the biological processes to prevent PCO. In this type of prevention, the use of nanotechnological advances can play a role.

Coculture with intraocular lens material-activated macrophages induces an inflammatory phenotype in lens epithelial cells

Cataracts are the leading cause of blindness worldwide, requiring surgical implantation of an intraocular lens. Despite evidence of leukocyte ingress into the postoperative lens, few studies have investigated the leukocyte response to intraocular lens materials. A novel coculture model was developed to examine macrophage activation by hydrophilic acrylic (poly(2-hydroxyethyl methacrylate)) and hydrophobic acrylic (polymethylmethacrylate) commercial intraocular lens. The human monocytic cell line THP-1 was differentiated into macrophages and cocultured with human lens epithelial cell line (HLE-B3) with or without an intraocular lens for one, two, four, or six days. Using flow cytometry and confocal microscopy, expression of the macrophage activation marker CD54 (intercellular adhesion molecule-1) and production of reactive oxygen species via the fluorogenic probe 2',7'-dichlorodihydrofluorescein diacetate were examined in macrophages. α-Smooth muscle actin, a transdifferentiation marker, was characterized in lens epithelial cells. The poly(2-hydroxyethyl methacrylate) intraocular lens prevented adhesion but induced significant macrophage activation (p < 0.03) versus control (no intraocular lens), while the polymethylmethacrylate intraocular lens enabled adhesion and multinucleated fusion, but induced no significant activation. Coculture with either intraocular lens increased reactive oxygen species production in macrophages after one day (p < 0.03) and increased expression of α-smooth muscle actin in HLE B-3 after six days, although only poly(2-hydroxyethyl methacrylate) induced a significant difference versus control (p < 0.01). Our results imply that-contrary to prior uveal biocompatibility understanding-macrophage adherence is not necessary for a strong inflammatory response to an intraocular lens, with hydrophilic surfaces inducing higher activation than hydrophobic surfaces. These findings provide a new method of inquiry into uveal biocompatibility, specifically through the quantification of cell-surface markers of leukocyte activation.

The intraocular lens: challenges in the prevention and therapy of infectious endophthalmitis and posterior capsular opacification

Cataract is the leading cause of visual impairment worldwide. In the UK, some 30% of the population over 65 years of age have visually impairing cataract. Importantly, 88% of those with treatable visual impairment from cataract are not in contact with any ocular healthcare service, representing a major potential healthcare need [1]. In the USA, it has been estimated that 17.2% of the population (approximately 20.5 million) over 40 years of age have cataract in either eye and by 2020, this number is expected to rise to 30.1 million. Currently, cataract is responsible for 60% of Medicare costs associated with vision [2]. Furthermore, as the populations of industrialized countries such as the UK and the USA continue to age, the costs associated with treatment of cataract can only be expected to increase. Consequently, the development of the intraocular lens to replace the cataractous lens and the advances in intraocular lens design and implantation represent a major development in cataract treatment. However, despite such advances, cataract surgery is not without complications, such as postoperative infectious endophthalmitis, a rare but potentially devastating condition, and posterior capsular opacification, a less serious but much more common problem. This review will examine the epidemiology of cataracts, the polymeric construction of intraocular lenses implanted during cataract surgery and the complications of postoperative infectious endophthalmitis and posterior capsular opacification with regard to therapeutic interventions and prophylactic strategies. Advances in biomaterial design and function will be discussed as novel approaches to prevent such postoperative complications.

Comparison of clinical efficacy: Nd:YAG laser rates after implantation of AcrySof® SN60WF, Akreos® AO-MI60 and Hoya® YA-60BB

PURPOSE

To compare Nd:YAG laser rates following implantation of AcrySof(®) SN60WF (Alcon), Akreos(®) AO-MI60 (Baush & Lomb), and Hoya(®) YA-60BB (Hoya) intraocular lenses.

METHODS

This retrospective study was conducted at three French centers with each implanting at least two of the three implants. Included patients had undergone uncomplicated cataract surgery with at least 3 years of follow-up. Records of patients implanted with one of the three IOL's were drawn randomly from the surgical logs. Postoperative data were obtained from the medical records of either the surgeon or the referring physician. Time elapsing until Nd:YAG laser was analysed using Kaplan-Meier survival curves.

RESULTS

Three hundred eyes were implanted (AcrySof(®) 126, Akreos(®) 89, and Hoya(®) 85). AcrySof(®) recipients were the youngest (AcrySof(®) 72.1, Akreos(®) 76.4, and Hoya(®) 75.2 years of age: P=0.0007). The sex ratio was 4:6 male:female. Follow-up was longest for Hoya eyes (AcrySof(®) 29.4, Akreos(®) 24.6 and Hoya(®) 34.6 months; P=0.0002). Eyes implanted with AcrySof(®) had 1.74 times less chance of Nd:YAG laser treatment than Hoya eyes (P=0.0327) and 3.50 times less than Akreos(®) eyes (P<0.0001). The results remained unchanged when the analysis was restricted to events in the first 24 months (Risk Ratios: Hoya(®)=2.64: P=0.02; and Akreos(®)=4.22: P=0.0001). Adjustment on unbalanced confounding variables did not alter the results.

CONCLUSIONS

Eyes with AcrySof(®) implants required significantly fewer Nd:YAG laser capsulotomies than those with Hoya(®) and Akreos(®) implants and were therefore less subject to Nd:YAG laser treatment complications, thus ensuring better vision at the lowest cost.

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.

Incidence of Nd:YAG laser capsulotomies after cataract surgery: comparison of 3 square-edged lenses of different composition

OBJECTIVE

To compare the incidence of Nd:YAG laser treatment following 3 square-edged intraocular lenses (IOLs) of different composition implanted during cataract surgery.

DESIGN

Patient chart analysis.

PARTICIPANTS

Patients aged 50-85 years and given a hydrophobic acrylic IOL (either SA60AT or AR40E) or hydrophilic acrylic IOL (XL-Stabi) were included. Analysis was conducted of 767 eyes treated with SA60AT (n = 250), AR40E (n = 254), or XL-Stabi (n = 263).

METHODS

This retrospective study involved patients who had undergone cataract surgery between 2001 and 2002. Ophthalmology centres were accepted into the study if they used at least 2 of the IOLs being investigated. The medical files of patients fulfilling the inclusion criteria were listed, and eligible cases were selected randomly. Patients' characteristics were obtained from their medical files. Data on postsurgical complications and Nd:YAG laser treatment over 3 years were also extracted. Follow-up data were obtained from the medical files and the patients' ophthalmologists. Time to Nd:YAG laser treatment was analysed using Kaplan-Meier survival curves adjusted with a Cox model.

RESULTS

After 3 years' follow-up the proportions of patients who had not received Nd:YAG laser treatment were 87.0% with SA60AT, 76.6% with AR40E, and 54.6% with XL-Stabi (p < 0.001). Cox's model adjusted for centre effects and the presence of diabetes estimated risk ratios of 2.8 for AR40E (p < 0.0005) and 5.1 for XL-Stabi (p < 0.0001), compared with the reference lens SA60AT.

CONCLUSIONS

Of the 3 square-edged lenses studied, the SA60AT was associated with a lower incidence of Nd:YAG laser treatment than either AR40E or XL-Stabi.

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.

Effect of intraocular lens edge profile on posterior capsule opacification after extracapsular cataract surgery in a developing country

PURPOSE

To determine whether square-edged polymethyl methacrylate (PMMA) intraocular lenses (IOLs) reduce posterior capsule opacification (PCO) in the context of extracapsular cataract surgery in a developing country.

SETTING

A rural hospital in India.

METHODS

This was a prospective randomized double-masked fellow-eye controlled study. Over a 4-month period, 118 patients with normal eyes apart from age-related cataract were randomized to receive a square-edged or round-edged PMMA IOL in the first eye. The IOLs were identical apart from the edge profile. The fellow-eye had implantation of the alternative IOL within 1 month. Retroillumination images of the posterior capsule were taken using a dedicated camera system and analyzed to quantify the PCO area using POCO software 1 and 2 years postoperatively and the PCO area and severity using POCOman semiqualitative software at 2 years. Visual acuity was measured using a Gujarati logMAR chart.

RESULTS

One hundred fifteen patients were available for examination at 1 year and 107 at 2 years. With POCO software, the PCO area was reduced in the square-edged IOL group at 1 year (median 30% versus 20%, P=.001) and at 2 years (median 45% versus 35%, P=.006). With POCOman, the PCO area and severity were reduced in the square-edged group at 2 years (median 41.5% versus 33.2%, P=.019 and 0.59 versus 0.46, P=.037, respectively). There was no significant difference in visual acuity between the 2 groups at 1 or 2 years.

CONCLUSIONS

Sophisticated image analysis techniques can be used in developing countries to quantify PCO. Using extracapsular surgery, square-edged PMMA IOLs reduced the PCO area and severity compared with an identical round-edged IOL; however, the differences were not as marked as those reported with phacoemulsification. This may be due to the difficulty of performing a capsulorhexis that lies on the IOL surface in this situation. Nevertheless, square-edged IOLs offer a potential benefit for extracapsular surgery in the developing world.

Preoperative opacification of acrylic intraocular lenses in storage

The preoperative opacification of acrylic intraocular lenses (IOLs) was investigated in order to determine its cause. Opacified IOLs were examined by energy dispersive X-ray (EDX), the buffer solutions were analysed by inductively coupled plasma optical emission spectroscopy (ICP-OES) and the rubber seals used in the bottles in which the IOLs were stored were ashed and tested. The deposit covering the opacified lenses contained a significant amount of zinc, which was absent from fresh IOLs and buffer solution. The source of this was found to be the rubber seals used to seal the glass bottles in which the IOLs were stored. There were two types of rubber seals used, red and grey in colour. The buffer solutions in which opacification had occurred was also contaminated with zinc, but this was only noticeable when using the red seals. This contamination was reproduced by boiling red seals in fresh buffer solution for eighty minutes, to simulate autoclaving. It was concluded that zinc from the zinc oxide used as filler in the rubber seals was leaching into the buffer solution and causing the IOLs to become opacified. This was found to be much worse in the case of the red seals than for the grey ones. However, minute crystals were found on the IOLs stored using the grey ones, which could potentially act as nucleation points for postoperative opacification.

Efficacy of different intraocular lens materials and optic edge designs in preventing posterior capsular opacification: a meta-analysis

PURPOSE

To evaluate the efficacy of different intraocular lens (IOL) materials and optic edge designs in preventing posterior capsular opacification (PCO).

DESIGN

Systematic review and meta-analysis.

METHODS

Pertinent studies were selected through an electronic search of the Cochrane Library, MEDLINE, and Embase. The randomized controlled trials meeting the predefined criteria were reviewed systematically by meta-analysis. The treatment effects were measured as risk difference, and the pooled estimates were computed according to a random effect model.

RESULTS

In total, 23 randomized controlled trials were included in the present meta-analysis. The pooled risk differences of Nd:YAG laser capsulotomy rates were -24% (95% confidence interval [CI], -29% to -20%) comparing acrylic with polymethylmethacrylate (PMMA) lenses; -9% (95% CI, -17% to -1%) comparing silicone with PMMA lenses; 14% (95% CI, -8% to 36%) comparing hydrogel with PMMA lenses; 4% (95% CI, -2% to 10%) comparing silicone with acrylic lenses; 19% (95% CI, 8% to 30%) comparing hydrogel with acrylic lenses; and 28% (95% CI, 10% to 46%) comparing hydrogel with silicone lenses. The pooled risk differences of PCO rates were -39% (95% CI, -47% to -31%) comparing acrylic with PMMA lenses; -14% (95% CI, -29% to 0%) comparing silicone with acrylic lenses; 56% (95% CI, 36% to 75%) comparing hydrogel with acrylic lenses; and 48% (95% CI, 31% to 64%) comparing hydrogel with silicone lenses. When comparing sharp with rounded-edge designs, pooled risk differences of capsulotomy rates were -47% (95% CI, -77% to -17%) in PMMA lenses, -22% (95% CI, -47% to 2%) in acrylic lenses, and -9% (95% CI, -17% to 0%) in silicone lenses; pooled risk differences of PCO rates were -28% (95% CI, -50% to -7%) in acrylic lenses and -37% (95% CI, -46% to -27%) in silicone lenses.

CONCLUSIONS

The rates of PCO and Nd:YAG laser capsulotomy may be influenced by different IOL biomaterials and optic edge designs. The lenses made by acrylic and silicone and those with sharp optic edges are superior in lowering the rates of PCO and laser capsulotomy.

Outcome of phacoemulsification in patients with uveitis

AIMS

To examine the visual outcome and identify risk factors for postoperative uveitis, macular oedema and neodymium-doped yttrium aluminium garnet (Nd:YAG) capsulotomy after phacoemulsification and intraocular lens (IOL) implantation in patients with uveitis.

METHOD

This is a retrospective review of the medical records of 101 eyes of 101 patients. One eye was randomly selected for inclusion in patients who had bilateral surgery. Patients with juvenile arthritis, keratouveitis and lymphoma-associated uveitis were excluded.

RESULTS

At the first postoperative and final visits, visual acuity was significantly better (p<0.001), and 64.4% and 71.3% of patients, respectively, had achieved >or=2 Snellen's lines of visual improvement. The cumulative probability of doubling of the visual angle was 52% over 6 years of follow-up, and this occurred at a higher rate in the presence of preoperative retinal or optic nerve lesions (HR (95% CI) 4.49 (1.41 to 14.29)). Within 3 months after operation, uveitis was more likely to develop in female patients (OR (95% CI) 6.21 (1.41 to 27.43)) and in the presence of significant intraoperative posterior synechiae (OR (95% CI) 8.43 (1.09 to 65.41)); macular oedema was more likely to develop in patients who developed postoperative uveitis (OR (95% CI) 7.45 (1.63 to 34.16)). Nd:YAG capsulotomy occurred at a higher rate in patients aged <or=55 years (HR (95% CI) 2.28 (1.06, 4.93)) and in those with hydrogel IOLs (HR (95% CI) 3.71 (1.04 to 13.20)), and occurred at a lower rate in patients who had prophylactic systemic corticosteroids (HR (95% CI) 0.25 (0.11 to 0.59)), with plate-haptic silicone IOLs (HR (95% CI) 0.23 (0.08 to 0.64)) and three-piece silicone IOLs (HR (95% CI) 0.19 (0.05 to 0.74)) in comparison to those with polymethylmethacrylate IOLs.

CONCLUSION

Most patients with uveitis achieve improved visual acuity after phacoemulsification, but an increasing rate of visual loss is observed in those with pre-existent macular or optic nerve lesions. Identifying patients who are at risk of postoperative complications should help in patient counselling and to pre-empt these complications by using preoperative prophylactic corticosteroids, careful IOL selection and postoperative intensive corticosteroids.

Outcome of posterior capsulotomy in late capsular block syndrome with posterior capsular opacification

BACKGROUND

To examine the results of neodymium:yttrium-aluminium-garnet (Nd:YAG) laser posterior capsulotomy in eyes with late or previously unrecognized capsular block syndrome (CBS) presenting with deterioration of vision owing to posterior capsular opacification (PCO).

METHODS

Patients, who underwent uneventful phacoemulsification with intraocular implantation and were referred for Nd:YAG laser capsulotomy owing to PCO, were prospectively examined for the presence of CBS. When indicated, Nd:YAG laser posterior capsulotomy was carried out. Prospective follow-up examinations were performed for the next 6 months. The outcome measures were post-laser change in best corrected visual acuity, refraction, change in intraocular pressure, inflammation and complication rate.

RESULTS

Of 655 patients referred for capsulotomy, eight had an associated CBS in that eye. These eight eyes comprised the study cases. The presence of CBS had not been recognized before the development of PCO. Best corrected visual acuity improved in all cases. In seven out of eight (87.5%) eyes refraction was unchanged throughout the follow up. Ocular hypertension, inflammation or other complications did not develop.

CONCLUSION

Nd:YAG laser capsulotomy in eyes with PCO and late or previously unrecognized CBS is a safe procedure, resulting in improved visual acuity without refractive change.

Opacification of the Hydroview H60M intraocular lens: total patient recall

PURPOSE

To report the prevalence of intraocular lens (IOL) opacification and related clinical features in patients implanted with Hydroview IOL.

SETTING

Gloucestershire Eye Unit, Gloucestershire, United Kingdom.

METHODS

A total of 1330 eyes of 1265 patients who had cataract surgery with Hydroview IOL implantation between September 2000 and April 2001 were reviewed between April and October 2004. The visual acuity, visual symptoms, IOL status, and associated ocular comorbidity were recorded.

RESULTS

One hundred ninety-three (14.5%) of 1330 eyes had evidence of IOL opacification. A total of 56 (4.2%) had visually significant opacification and had IOL exchange. The prevalence of IOL opacification ranged from 1.1% in patients who had surgery in September 2000 to 36.3% in the December 2000 group. In eyes with IOL opacification, the visual symptoms were decreased vision (57%), glare (32%), and mistiness of vision (27%). One hundred forty-four eyes (75%) with IOL opacification had visual acuity of 6/12 or better; 21.5% of diabetic eyes had IOL opacification compared with 14.3% of nondiabetic eyes (P =.06); 20.5% of glaucomatous eyes had IOL opacification compared with 14.0% of nonglaucomatous eyes (P = .033).

CONCLUSIONS

This is the first large sample recall of patients implanted with the Hydroview H60M IOL. The overall prevalence of IOL opacification was 14.5%, with peak prevalence in patients who had surgery in December 2000.

Modification of the surface properties of a lens material to influence posterior capsular opacification

PURPOSE

To study the effect of surface properties of materials on cellular behaviour and the formation of posterior capsular opacification (PCO).

METHODS

Polymethylmethacrylate, silicone and a hydrophobic acrylic were plasma treated and used in tissue culture. The changes in surface properties were quantified by dynamic contact angle measurements. Bovine lens epithelial cells (BLECs) were seeded onto these materials and cultured for 1 month. Serial photographs were taken. The cells were then fixed and stained to facilitate counting.

RESULTS

Plasma treatment significantly increased the hydrophilicity of surfaces. BLECs grew on all surfaces but significantly more cells adhered to the treated than the untreated surfaces. On the untreated surfaces the BLECs had a fibroblastic morphology whereas on the treated surfaces the cells maintained their epithelial morphology.

CONCLUSIONS

Posterior capsular opacification is a form of wound healing and the behaviour of lens epithelial cells is central to its progression. Emphasis has been on the elimination of residual lens epithelial cells to combat PCO. This study demonstrated that the phenotype of BLECs was influenced by the surface properties of the intraocular lens materials. Gas plasma treatment of the materials increased their hydrophilicity and allowed the adhered BLECs to maintain their normal epithelial morphology. We believe that controlled growth of lens epithelial cells may reduce the incidence of PCO.

[Posterior capsule opacification after phacoemulsification in patients with rheumatoid arthritis]

PURPOSE

To assess the posterior capsule opacification (PCO) rate after phacoemulsification with polyacrylic intraocular lens (IOL) implantation in patients with rheumatoid arthritis (RA) compared with the controls, and to assess whether preoperative activity of RA is associated with a higher incidence of PCO.

METHODS

24 eyes of 20 RA patients operated in a period of 4 years were included in our study. A control group of 20 eyes from 20 health subjects were also included in our study. All procedures were performed by a single surgeon with the same surgical technique and postoperative medication.

RESULTS

One year postoperatively in two eyes (8.3%) of RA-patients lens epithelial cells (LEC) migration of grade 1 was observed, in controls also in two eyes (10%). No correlation was observed between age, duration of RA or preoperative activity of RA and the PCO rate.

CONCLUSION

Following acrylic IOL implantation, the PCO rate one year after surgery was 8.3% in RA patients and 10% in controls. RA patients present no higher risk for PCO development than controls.

Hydrophobic acrylic and plate-haptic silicone intraocular lens implantation in diabetic patients

PURPOSE

To compare the capsular and uveal reaction after implantation of a plate-haptic silicone intraocular lens (IOL) (C11UB, Chiron) and a hydrophobic acrylic (AcrySof MA60, Alcon) IOL in diabetic patients.

SETTING

Moorfields Eye Hospital and St. Thomas' Hospital, London, United Kingdom.

METHODS

Thirty-five diabetic patients were recruited consecutively and randomly assigned to have implantation of either of the 2 IOLs. The percentage area of posterior capsule opacification (PCO), anterior capsule contraction (ACC), and postoperative inflammatory indices (flare and cells) were assessed objectively at 2 to 3 weeks, 6 months, and 1 year. Between-group and within-group analyses were conducted using the Student t test or Mann-Whitney test and Friedmann test, respectively.

RESULTS

Between-group analysis showed the percentage area of PCO was significantly greater in patients with plate-haptic silicone IOLs at 6 and 12 months (P = .002). At 6 months, ACC was significantly greater in the plate-haptic group (P = .04), but the difference was not significant at 12 months. There was higher flare in the hydrophobic acrylic IOL group than in the plate-haptic silicone IOL group at 2 to 3 weeks (P = .08). Within-group analysis showed that over the follow-up period, the plate-haptic silicone group, but not the hydrophobic acrylic group, had a progressive increase in PCO (P = .003). In the hydrophobic acrylic group, but not the plate-haptic silicone group, there was a significant reduction in the mean anterior chamber flare value (P = .01). There was no significant difference in visual acuity or contrast sensitivity at any postoperative visit.

CONCLUSION

In diabetic patients, hydrophobic acrylic IOLs can lead to an increased flare in the early postoperative period but they seem to be more favorable than plate-haptic silicone IOLs because the latter lead to more PCO.

Identification of a retrolental membrane during laser capsulotomy in eyes with a Hydroview intraocular lens

We report our observation of a distinct membrane on the posterior surface of the Hydroview (Bausch & Lomb Surgical) intraocular lens during laser capsulotomy in 6 patients. In 3 patients, the retrolental membrane was noted during 4 to 6 weeks of follow-up after laser capsulotomy. The technique of a 2-stage laser capsulotomy in this group of patients is described. The possible cause and significance for this observation are also discussed.

Assessment of the validity of in vivo methods of measuring human macular pigment optical density

PURPOSE

As a result of the putative protective role of lutein and zeaxanthin at the site of the retina (macular pigment [MP]), interest in the noninvasive measurement of these retinal carotenoids is increasing. In principle, any method used to measure MP in vivo should provide spectral absorption curves that match extinction spectra of MP measured ex vivo.

METHODS

In this article, we assess published spectral curves with respect to this criterion.

RESULTS AND DISCUSSION

Variation in derived MP measures resulting from methodological differences between techniques is noted and discussed.

Preventing recurrent opacification of the visual pathway after pediatric cataract surgery

PURPOSE

To determine the rate of secondary opacification of the visual pathway following pediatric cataract surgery in children between the ages of 10 months and 7 years.

METHODS

The medical records of children less than 7 years old who underwent lens aspiration, posterior chamber intraocular lens (IOL) implantation, primary pars plana posterior capsulectomy, and anterior vitrectomy were reviewed retrospectively. Twenty-six eyes in 19 children were included in the study. All procedures were performed by an anterior segment surgeon and a vitreoretinal surgeon. Main outcome measures were the prevalence of re-opacification of the visual pathway and of early postoperative complications.

RESULTS

The visual pathway remained clear in 25 of 26 eyes (96%) after pediatric cataract surgery combined with primary pars plana posterior capsulectomy and anterior vitrectomy. The mean age at surgery was 46 +/- 23 months (+/-SD). Secondary opacification of the visual pathway occurred in one eye (4%), requiring another surgical procedure. At last follow-up (mean, 26 months; range, 6 to 79 months), the visual pathway was clear in all 26 eyes (100%). No cases of clinically significant IOL displacement or of retinal detachment were noted.

CONCLUSIONS

For children undergoing pediatric cataract surgery between the ages of 10 months and 7 years, IOL implantation combined with primary pars plana posterior capsulectomy and anterior vitrectomy is effective in preventing re-opacification of the visual pathway.

Adverse clinical consequences of neodymium:YAG laser treatment of posterior capsule opacification

PURPOSE

To evaluate the clinical consequences of complications from neodymium:YAG (Nd:YAG) laser capsulotomy for posterior capsule opacification (PCO) over the lives of cataract patients.

SETTING

CHU de Caen, Caen, France.

METHODS

A model was constructed to estimate the lifetime clinical consequences of postoperative PCO treated by Nd:YAG laser capsulotomy. The probability of death was modeled from French mortality tables as a polynomial function of sex and age. The probability of becoming blind was modeled as a function of age from data in the literature. The incidence of Nd:YAG complications came from the literature. The rate of Nd:YAG capsulotomy over time was modeled as a survival curve using data from a cohort of 3335 patients.

RESULTS

Over 9 years in a 70-year-old population, switching from an IOL with a 20% Nd:YAG capsulotomy rate at 3 years to an IOL with a 5% rate would avoid 1 chronic intraocular pressure increase requiring medical follow-up in every 54 surgeries, 1 case of glaucoma in every 237 surgeries, 1 case of cystoid macular edema in every 265 surgeries, and 1 retinal detachment in every 265 surgeries. A 3-year clinical study would only capture one-third to one-half of long-term adverse events of Nd:YAG capsulotomy.

CONCLUSION

Reducing PCO and the associated use Nd:YAG laser capsulotomy may contribute to preserving visual acuity in patients over their lifetimes.

Phacoemulsification after retinal detachment surgery

PURPOSE

To evaluate the outcomes of phacoemulsification in eyes that had previous retinal detachment (RD) surgery.

SETTING

Hayashi Eye Hospital, Fukuoka, Japan.

METHODS

Ninety-six eyes of 90 consecutive patients who had phacoemulsification after previous RD surgery (RD group) were included. Fifty-one fellow eyes that had not had RD surgery but did have phacoemulsification served as controls (control group). Recurrence of RD, visual acuity, complications, and the neodymium:YAG (Nd:YAG) laser capsulotomy rate were examined.

RESULTS

Recurrent RD after phacoemulsification occurred in 2 eyes (2.1%) in the RD group. Three eyes (5.9%) in the control group developed RD postoperatively. The incidence of RD was not significantly different between the 2 groups (P =.3416). The mean final visual acuity in the RD group was 20/30, significantly worse than in the control group (P =.0099). Posterior capsule opacification developed in 29 eyes (30.2%) in the RD group and 11 eyes (21.6%) in the control group; the difference between the groups was not significant. Eighteen eyes (43.9%) that had implantation of a poly(methyl methacrylate) (PMMA) intraocular lens (IOL) and 7 eyes (6.6%) that received an acrylic IOL had an Nd:YAG capsulotomy; the capsulotomy rate was significantly higher in eyes with a PMMA IOL than in eyes with an acrylic IOL (P<.0001).

CONCLUSIONS

The rate of recurrent RD after phacoemulsification in eyes that had previous RD surgery was similar to that of new occurrence of RD in fellow eyes without RD before phacoemulsification. Because the Nd:YAG capsulotomy rate was lower in eyes with acrylic IOLs than in eyes with PMMA IOLs, acrylic IOLs are recommended for eyes at high risk for RD.

Relationship between posterior capsule opacification and intraocular lens biocompatibility

The type of healing process that occurs in response to cataract surgery and intraocular lens (IOL) implantation is dependent on a complex set of variables. Their interactions determine whether or not optical clarity is restored as a result of this procedure. In this process, wound healing entails cells undergoing either epithelial-mesenchymal transition, resulting in the generation of fibroblastic cells and accumulation of extracellular matrix, or lenticular structure formation. Such desperate cellular behaviors are regulated by the localized release of different cytokines, including transforming growth factor beta and fibroblast growth factors, which can result in post-operative capsular opacification. Other factors affecting the biological and mechanical outcome of IOL implantation are its composition, surface properties and shape.

Bendazac Lysine Inhibition of Human Lens Epithelial Cell Adhesion to Polymethylmethacrylate Intraocular Lenses

The aim of the present work was to evaluate the effect of bendazac lysine on the human lens epithelial cell line HLE-B3 adhesion to polymethylmethacrylate (PMMA) intraocular lenses (IOLs). After adherence to IOLs, cells were incubated in the presence of the drug for 24 h. The number of cells contained in a 6-mm(2) area was then counted with an inverted phase microscope and adherent cells were distinguished from detached floating cells by focusing through the medium. Results obtained show that bendazac is able to induce a linear dose-dependent inhibition of HLE-B3 adhesiveness to PMMA IOLs. In particular, treatment with bendazac 33, 100 and 300 microM resulted in a 15, 32 and 54% inhibition, respectively. Statistical analysis shows that this effect is significant at 100 microM (p < 0.05) and 300 microM (p < 0.01). The analysis of the effects of bendazac on the viability and on the proliferative capacity of HLE-B3 cells did not show any drug-related toxicity up to the concentration of 400 microM. The present study demonstrates that bendazac lysine is able to inhibit adhesion of lens epithelial cells to PMMA IOLs and suggests the potential beneficial use of this drug in preventing secondary cataract development.

Pseudoexfoliation syndrome: pathological manifestations of relevance to intraocular surgery

Pseudoexfoliation syndrome (PEX) is a common ocular condition often associated with the need for intraocular surgery. Although results of cataract and glaucoma filtering surgery in eyes with PEX in the early stages of the disease may be comparable to those in eyes without PEX, in the later stages morbidity is significantly increased due to periocular surgical complications and the outcome is worse. Surgical and postoperative difficulties are often multifactorial and are directly related to the pathological changes of PEX on intraocular structures. Recent years have seen a large increase in the understanding of the effects of PEX on the various ocular tissues. Although the visible areas of the anterior capsule are most obviously involved, this is only a small part of the picture and of least significance. Biomicroscopically invisible changes of the zonules and their attachments are of greatest consequence. There is also distinct, often active, involvement of almost all tissues of the anterior segment of the eye, many of which have important implications for the anterior segment surgeon including iridopathy, iris vasculopathy (including persistent breakdown of the blood-aqueous barrier and anterior segment hypoxia), ciliary body involvement and keratopathy. Trabecular dysfunction is evident by the deposition of PEX material derived from both in situ and extra-trabecular production as well as protein and melanin deposition. These changes should be kept in mind by all intraocular surgeons as a source of potential difficulties in the perioperative period. Additionally, in light of these changes, patients need to be given realistic expectations regarding the increased risk of complications and more prolonged expected recovery time. In this short review, current reports relating to PEX pathological changes of practical interest to the intraocular surgeon are summarized.

Posterior capsule opacification after implantation of a hydrogel intraocular lens

AIM

To compare the degree of posterior capsule opacification (PCO) in eyes with a hydrophilic hydrogel intraocular lens (IOL) with that in eyes with a hydrophobic acrylic IOL.

METHODS

Ninety five patients underwent a hydrogel IOL implantation in one eye and an acrylic IOL implantation in the opposite eye. The PCO value of these patients was measured using the Scheimpflug videophotography system at 1, 6, 12, 18, and 24 months postoperatively. The rate of neodymium:YAG (Nd:YAG) laser posterior capsulotomy and visual acuity were also evaluated.

RESULTS

The mean PCO value in the hydrogel group increased significantly (p<0.0001), while that in the acrylic group did not show significant change. The PCO value in the hydrogel group was significantly greater than that in the acrylic group throughout the follow up period. Kaplan-Meier survival analysis determined that the Nd:YAG capsulotomy rate in the hydrogel group was significantly higher than that in the acrylic group (p<0.0001). Mean visual acuity in the hydrogel group decreased significantly with time (p<0.0001), and became significantly worse than that in the acrylic group at 18 and 24 months postoperatively.

CONCLUSION

Posterior capsule opacification in eyes with a hydrophilic hydrogel IOL is significantly more extensive than that in eyes with a hydrophobic acrylic IOL, and results in a significant impairment of visual acuity.

Use of Nd:YAG laser capsulotomy

Surgery for cataract removal has become successively refined such that posterior capsular opacification is the most common problem presenting after modern cataract extraction. Various techniques and treatments exist to manage patients with posterior capsular opacification using Nd:YAG capsulotomy. There are many possible variations in initial assessment, pre-laser treatments, laser techniques, and follow-up routines. The literature on the use of Nd:YAG laser for capsulotomy was reviewed and interpreted. This article presents the currently available knowledge in a format that allows the practitioner to tailor an evidence-based protocol for treating patients with symptomatic posterior capsule opacification.

Biocompatibility of intraocular lenses

PURPOSE

The choice of intraocular lens (IOL) implanted by cataract surgeons has significant implications for the effectiveness of the operation and the subsequent need for capsulotomy.

METHODS

Comparison of pertinent peer-reviewed literature published from 1996 through 2001 obtained from a MEDLINE literature search on biocompatibility indicators and IOLs. This review pertains to routine, uncomplicated cataract surgery, and thus, the findings may not be relative to complicated surgeries. Currently available IOLs were not included in this review if no published data on the IOL were available. However, representative lenses from all the major biomaterial classes were included.

RESULTS

Overall results of a comparison of published accounts of posterior capsular opacification, Nd:YAG capsulotomies, anterior capsular opacification, aqueous flare, cellular reaction, capsular adhesion, and capsular stability show a polyacrylic elastomer to be the most highly biointegrated IOLs by the human eye.

CONCLUSIONS

Most evidence published in peer-reviewed journals suggests a clear IOL choice for cataract surgeons. In the field of implantable medical devices, one device in a category does not usually provide consistently superior performance of its intended function. The ability of the biomaterial to maintain a clear optical axis not only by suppressing the proliferation of lens epithelial cells, and thus inhibiting posterior capsular opacification formation and obviating the need for an Nd:YAG capsulotomy, but also by adhering to and stabilizing the capsular bag is, to date, unmatched by any other IOL available.

Histology of anterior capsule opacification with a polyHEMA/HOHEXMA hydrophilic hydrogel intraocular lens compared to poly(methyl methacrylate), silicone, and acrylic lenses

To evaluate the biocompatibility of various materials including a poly(2-hydroxyethyl methacrylate [HEMA])/(6-hydroxyhexyl methacrylate [HOHEXMA]) hydrophilic hydrogel intraocular lens (IOL) (Hydroview, Bausch & Lomb). Department of Ophthalmology, Wakayama Medical University, Wakayama, Japan. Ten opacified anterior capsules were extracted, including 3 specimens with the Hydroview IOL. They were processed for light and electron microscopy. Immunohistochemistry for alpha-smooth muscle actin (alpha SMA) and collagen types was also done to evaluate mesenchymal transition in lens epithelial cells (LECs). Anterior capsule opacification (ACO) in the 3 specimens with a polyHEMA/HOHEXMA hydrogel IOL contained more LECs and less extracellular matrix (ECM) than in the specimens with IOLs of other materials. Ultrastructural observation showed a well-organized collagenous ECM in tissues with an IOL of poly(methyl methacrylate), silicone, or soft acrylic material; an immature matrix was seen in specimens with a hydrogel IOL. The alpha SMA-positive LECs and collagen I and III, both types related to capsular wound healing, were detected in ACO.A polyHEMA/HOHEXMA hydrogel IOL facilitated the proliferation of LECs on the anterior capsule compared with other IOLs of other materials but did not completely suppress mesenchymal transition of LECs. Extracellular matrix accumulation appeared immature and less with a polyHEMA/HOHEXMA hydrogel IOL.

Systems of analysis of posterior capsule opacification

This paper demonstrates the wide variety of systems for the analysis of posterior capsular opacification (PCO). No single system has been proved to be a gold standard and it is difficult to comment on the advantages of one system over another with the limited current knowledge on the effects of PCO on vision. There are few studies that actually compare the different systems of analysis. Researchers must ensure that the systems they use for PCO analysis are objective and must give maximum consideration to ensuring potential systematic errors are reduced to a minimum. Further research is required into how the various types and locations of PCO affect vision and how well different systems of analysis perform.

Uveal and capsular biocompatibility of 2 foldable acrylic intraocular lenses in patients with uveitis or pseudoexfoliation syndrome: comparison to a control group

PURPOSE

To evaluate the uveal and capsular biocompatibility of hydrophilic acrylic (Hydroview) and hydrophobic acrylic (AcrySof) intraocular lenses (IOLs) after phacoemulsification in eyes with pseudoexfoliation syndrome (PEX) or uveitis and compare the results with those in a control group.

SETTING

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

METHODS

This prospective nonrandomized comparative trial comprised 143 eyes recruited consecutively. Of these, 49 eyes had PEX, 43 had uveitis, and 51 served as controls. A standardized surgical protocol was used. Cell reaction, anterior (ACO) and posterior (PCO) capsule opacification, and flare were evaluated 1 year after cataract surgery.

RESULTS

Regarding uveal biocompatibility, the number of foreign-body giant cells (FBGCs) increased in proportion to associated ocular pathologies in both IOL groups. The difference between the Hydroview control and Hydroview uveitis groups was statistically significant. The number of FBGCs was greater on AcrySof IOLs than on Hydroview IOLs in all 3 groups. The difference in FBGCs between the 2 IOL types was statistically significant in the control and PEX groups. Regarding capsular biocompatibility, lens epithelial cell (LEC) outgrowth was inversely correlated with intraocular inflammation. Outgrowth was statistically significantly higher with Hydroview IOLs, occurring in 85% in the control group, 45% in the PEX group, and 28% in the uveitis group (P <.0001). With AcrySof lenses, the percentages were 0%, 8%, and 4%, respectively. The PEX and uveitis groups were more likely to develop ACO than the control group (P <.012). There was no statistically significant difference in ACO between the 2 IOL types in the 3 patient groups. The PCO was statistically significantly greater in the uveitis group than in the control group (P <.026) and statistically significantly more dense on Hydroview than on AcrySof IOLs in all 3 patient groups (P <.002). Flare was statistically significantly higher in the uveitis group than in the PEX and control groups with both IOL types (P <.012). There was no statistically significant difference in flare between the 2 IOL types.

CONCLUSIONS

Uveal and capsular biocompatibility depends on the intensity of ocular inflammation. The greater the inflammation, the less the biocompatibility of hydrophilic and hydrophobic acrylic materials. AcrySof stimulated more FBGCs. The Hydroview material had better uveal but poorer capsular biocompatibility than AcrySof. The sharp optic edge effect of the AcrySof IOL and the advantages of the Hydroview lens in normal eyes are less apparent in compromised eyes.

Survey of intraocular lens material and design

Modern cataract surgery is constantly evolving and improving in terms of lens material and design. Researchers and physicians strive to obtain better refractive correction with smaller wound size and minimizing host cell response to limit the proliferation of lens epithelial cells leading to opacification of the lens capsule. Intraocular lens material varies in water content, refractive index, and tensile strength. Intraocular lens design has undergone revisions to prohibit lens epithelial cell migration and reflection of internal and external light. The evolution of intraocular lens and extracapsular cataract surgery has lead to faster postoperative recovery and better visual outcomes.

Risk factors for secondary membrane formation after removal of pediatric cataract

PURPOSE

To evaluate the incidence of secondary membrane formation, factors that lead to its development, and the frequency of procedures to treat these membranes in children after cataract surgery.

SETTING

Department of Pediatric Ophthalmology, Children's Hospital of Pittsburgh, Pittsburgh, Pennsylvania, USA.

METHODS

Clinical records of 152 patients (190 eyes) who had cataract extraction between January 1986 and 1996 were reviewed retrospectively. The mean follow-up was 6 years (range 2 to 13 years). Cataract surgery was performed through a limbal incision in all cases. Twenty-eight eyes had a primary posterior capsulectomy, and 120 eyes had posterior capsulectomy combined with an anterior vitrectomy. In 42 eyes, the posterior capsule was left intact. Nineteen eyes received a primary intraocular lens (IOL), 15 eyes received a secondary IOL, and 156 eyes were rehabilitated with spectacles or contact lenses.

RESULTS

Seventy-two eyes (37.9%) developed secondary membrane a mean of 8.9 months postoperatively (range 3 weeks to 53 months). Membranes occurred in 78.6% of eyes with an intact posterior capsule, 42.9% with posterior capsulectomy, and 22.5% with combined posterior capsulectomy and anterior vitrectomy. Secondary membrane formation was associated with not performing a posterior capsulectomy with anterior vitrectomy (P < .001) and the presence of a primary IOL (P < .001). Younger age at surgery increased the chance of secondary membrane formation in patients who had posterior capsulectomy and anterior vitrectomy (P < .01).

CONCLUSIONS

The younger the child at cataract surgery, the greater the risk of secondary membrane. Primary posterior capsulectomy combined with an anterior vitrectomy decreased but did not eliminate the incidence of secondary membrane.

Anterior capsule contraction and intraocular lens decentration and tilt after hydrogel lens implantation

AIM

To prospectively investigate changes in the area of the anterior capsule opening, and intraocular lens (IOL) decentration and tilt after implantation of a hydrogel IOL.

METHODS

100 patients underwent implantation of a hydrogel IOL in one eye and an acrylic IOL implantation in the opposite eye. The area of the anterior capsule opening, and the degree of IOL decentration and tilt were measured using the Scheimpflug videophotography system at 3 days, and at 1, 3, and 6 months postoperatively.

RESULTS

The mean anterior capsule opening area decreased significantly in both groups. At 6 months postoperatively, the area in the hydrogel group was significantly smaller than that in the acrylic group. The mean percentage of the area reduction in the hydrogel group was also significantly greater than that in the acrylic group, being 16.9% in the hydrogel group and 8.8% in the acrylic group. In contrast, IOL decentration and tilt did not progress in either group. No significant differences were found in the degree of IOL decentration and tilt throughout the follow up period.

CONCLUSIONS

Contraction of the anterior capsule opening was more extensive with the hydrogel IOL than with the acrylic IOL, but the degree of IOL decentration and tilt were similar for the two types of lenses studied.

Effect of intraocular lens haptic compressibility on the posterior lens capsule after cataract surgery

PURPOSE

To evaluate the effect of intraocular lens (IOL) haptic compressibility on the posterior capsule after cataract surgery.

SETTING

Teaching hospital, London, United Kingdom.

METHODS

In this randomized prospective study, 60 patients had standardized phacoemulsification with in-the-bag placement of a poly(methyl methacrylate) (PMMA) (Storz P497UV) or hydrogel (Storz Hydroview H60M) IOL. Both IOLs had PMMA haptics of identical configuration and length. The IOL haptic compressibility was measured in air and then during incubation in saline at 37 degrees C over 1 month. Digital retroillumination imaging was performed 1, 7, 28, 90, 180, 360, and 720 days postoperatively. The presence and duration of postoperative capsule folds were recorded and correlated with the haptic compressibility measurements, lens epithelial cell (LEC) growth patterns on the posterior capsule at 6 months, and the extent of posterior capsule opacification.

RESULTS

On the first postoperative day, 21 patients (88%) in the Hydroview group had posterior capsule folds that persisted in 12 patients (50%) for 2 years. Nineteen patients (68%) in the PMMA group had folds at day 1 (P =.01), with 1 patient (3%) still having folds at 1 month (P =.0002) and no patient having folds at 3 months. At 6 months, 11 patients (46%) in the Hydroview group and no patient in the PMMA group had LEC growth in the direction of the folds. The PMMA IOLs showed a greater decrease in haptic compressibility during incubation.

CONCLUSIONS

Haptic compressibility should be an important consideration in IOL design. The results suggest that to avoid posterior capsule folds, the compressibility should be less than 2.5 mN.

Effect of optic size on posterior capsule opacification: 5.5 mm versus 6.0 mm AcrySof intraocular lenses

PURPOSE

To determine the effect of intraocular lens (IOL) optic diameter on posterior capsule opacification (PCO) using digital retroillumination images.

SETTING

Eye Department, St. Thomas' Hospital, London, United Kingdom.

METHODS

In this prospective study, 60 patients with senile cataract had routine phacoemulsification by a single surgeon and received standardized medication. The patients were divided into 2 equal groups. The first group received a 5.5 mm 3-piece AcrySof IOL (MA30BM, Alcon) inserted in the bag. The second group received a 6.0 mm 3-piece AcrySof IOL (MA60BM, Alcon). Retroillumination images were obtained 1, 30, 90, 180, and 360 days postoperatively. The percentage area of PCO was calculated objectively by dedicated software at 90, 180, and 360 days. At 1 day, the degree of capsulorhexis-IOL contact was determined by inspecting the images.

RESULTS

Throughout the follow-up, there was less PCO in the 6.0 mm optic group than in the 5.5 mm optic group, and the difference reached significance 1 year postoperatively (P =.0017). At 1 year, the median percentage of PCO was 1.5% (95% confidence interval [CI] 1.4-5.3) in the 6.0 mm group and 6.9% (95% CI 5.8-18.0) in the 5.5 mm group.

CONCLUSIONS

A larger IOL optic diameter was associated with less PCO.

Capsulotomy

Research is continually seeking to better describe the relationship between pseudophakic capsular opacification and underlying cell biology, surgical technique, and intra-ocular lens biomaterial and design. Outcomes are reviewed from prospective, randomized studies that investigate the importance of capsulorhexis size, pharmacological treatment, and lens material in influencing capsular opacification and the need for capsulotomy. The results of several studies support the role of lens edge profile in inhibiting lens epithelial cell migration. A large post-mortem study also examines how lens type may affect anterior capsular opacification formation. Of particular interest is a histological report that sheds additional light on understanding cellular processes in posterior capsu-lar opacification.