Posterior capsule opacification and lens epithelial cell layer formation: Hydroview hydrogel versus AcrySof acrylic intraocular lenses

Delayed surface opacification of a hydroview intraocular lens

The insertion of an intraocular lens during cataract surgery is routine but delayed opacification of hydrophilic foldable intraocular lenses (IOLs) has been increasingly noticed as a late post-operative complication. Such opacification may present with reduced visual acuity and can be diagnosed with slitlamp biomicroscopy. Lens explantation may be required. We report an 89-year-old female presenting with opacification of a Hydroview IOL and correlate the clinical findings of the lens in situ with the light microscopy of the explanted lens, as well as transmission electron microscopy (TEM), scanning electron microscopy (SEM) and elemental analysis. Pathological analysis of an explanted IOL may assist in a better understanding of the condition and may become relevant in medico-legal proceedings.

A meta-analysis of Nd:YAG capsulotomy rates for two hydrophobic intraocular lens materials

Purpose

The purpose of this study is to estimate and compare neodymium-doped yttrium aluminum garnet (Nd:YAG) capsulotomy rates for AcrySof ^® and Clareon^® intraocular lens (IOL) materials using historical data from the medical literature and Alcon-sponsored clinical studies.

Methods

Clinical trials that involved the implantation of AcrySof or Clareon monofocal IOLs in subjects with cataract or presbyopia were extracted from the literature and a company repository of clinical studies. The study duration, number of eyes, and cumulative percent of Nd:YAGs for posterior capsule opacification were extracted. Bayesian random effects meta-analyses were conducted to estimate and compare outcomes for the 2 different IOL materials.

Results

A Bayesian random effects, meta-analysis was performed that combined a literature review of published AcrySof Nd:YAG posterior capsulotomy rates and Nd:YAG rates observed in Alcon-sponsored clinical studies of AcrySof and Clareon. Sixteen Alcon studies contained Nd:YAG data suitable for meta-analysis. Three of these Alcon studies contained results for the Clareon material (2 one-year studies, and 1 three-year study). The literature review included 50 papers from 1998 to 2015. In combination, 30,891 eyes were available for analysis and 2040 Nd:YAG procedures were reported in studies with a follow-up duration ranging in length from 4 months to 10 years. The overall probability of performing a Nd:YAG capsulotomy within a year of implant for AcrySof was 1.44% (1.11% to 1.83%) and 0.62% (0.21% to 1.38%) for Clareon. There was small improvement in the probability of Nd:YAG within a year of implant for Clareon lenses of about 0.82% with a 95% credible interval of (0.07% to 1.36%) at 1 year. Results were similar for incidence rates per 100 surgeries in a year: 0.62 (0.21 to 1.40) for Clareon, 1.46 (1.12 to 1.87) for AcrySof, and the difference was 0.84 (0.07 to 1.39) favoring Clareon. At 3 years, the overall probability of performing a Nd:YAG capsulotomy for AcrySof was 4.19% (3.24% to 5.30%) compared with only 1.82% (0.63% to 4.02%) for Clareon.

Conclusion

A meta-analysis of Clareon multi-piece and single-piece clinical data predicts that the cumulative Clareon Nd:YAG probability will be ≤ AcrySof by 2.37% (0.18% to 3.91%) at 3 years. The results indicate that Clareon is likely to perform as well as, and possibly better than, AcrySof in terms of Nd:YAG capsulotomy rates.

Comparison of pseudophakic retinal straylight in spherical/aspherical and hydrophobic/hydrophilic intraocular lens

AIM

To study the potential reasons of increased straylight in pseudophakic eyes.

METHODS

Cross-sectional study. Seventy patients diagnosed as bilateral age-related cataract and implanted with Tecnis ZA9003, Sensar AR40e, SA60AT, XLSTABI ZO or Akeros AO intraocular lens (IOL) were enrolled in this research. Straylight was measured by a C-Quant straylight meter three to four weeks postoperatively. Five different modalities of IOL, including spherical/aspherical optics and hydrophobic/hydrophilic material were tested in this study. Normal as well as dilated pupils were used. The main outcome variable for straylight measurement was the logarithmic straylight parameter, log(s).

RESULTS

The straylight parameter increased significantly after pupil dilation (P<0.05). Straylight of aspherical IOL was significantly higher after pupil dilation (P<0.05) compared to spherical IOL. In normal pupil, straylight of hydrophobic IOL was significant higher when compared with hydrophilic IOL (P<0.05).

CONCLUSION

Straylight and visual acuity stand for the different aspects of visual function. Several factors including pupil diameter, optic material, aspherical design of IOL influence intraocular light scattering in pseudophakic eyes. Further investigation was needed to study the impact of optic material and optic surface design on pseudophakic straylight.

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.

Reduction of Nd:YAG capsulotomy rates after implantation of a single-piece acrylic hydrophilic intraocular lens with 360° squared optic edge: 24-month results

BACKGROUND AND OBJECTIVE

Posterior capsule opacification remains a significant problem following cataract surgery. The aim of the study was to evaluate the incidence of symptomatic posterior capsule opacification requiring Nd:YAG capsulotomy in patients who underwent cataract extraction and implantation of the Rayner C-flex 570C intraocular lens (IOL) (Rayner Intraocular Lens, Ltd., Sussex, UK).

PATIENTS AND METHODS

A retrospective study of 3,461 eyes that underwent cataract extraction and insertion of the Rayner C-flex IOL from January 2004 to December 2005. The cases that received Nd: YAG capsulotomies were evaluated.

RESULTS

Over a 24-month period, 3,461 Rayner C-flex IOLs were implanted. Nd:YAG capsulotomy was performed in 58 of these cases. The rate of Nd:YAG capsulotomy was 0.6% at 12 months and 1.7% at 24 months. The mean time to Nd:YAG capsulotomy was 9.3 months (range: 1.3 to 22.7 months). The follow-up period was 5.3 to 29.0 months.

CONCLUSION

The incidence of symptomatic posterior capsule opacification with the Rayner C-flex IOL is low.

Determination of albumin sorption to intraocular lenses by radiolabeling and confocal laser scanning microscopy

PURPOSE

To determine albumin adsorption profiles and penetration depth of 3 intraocular lens (IOL) materials over time using confocal laser scanning microscopy (CLSM) and radiolabeling.

SETTING

Centre for Contact Lens Research, School of Optometry, and Department of Biology, University of Waterloo, Waterloo, Ontario, Canada.

METHODS

Poly(methyl methacrylate) (PMMA), silicone, and foldable hydrophilic acrylic IOLs were incubated in 0.5 mg/mL bovine serum albumin (BSA) for 1, 7, and 14 days. The BSA was conjugated with lucifer yellow VS to allow identification of the protein location by fluorescent imaging with CLSM. Next, the protein uptake was quantified using 2% (125)I-labeled BSA.

RESULTS

Confocal laser scanning microscopy showed increasing BSA uptake for silicone and PMMA IOLs after 14 days of incubation (P<.05), with an apparent penetration depth of 8.7 microm +/- 1.9 (SD) and 9.2 +/- 1.4 microm, respectively. For hydrophilic acrylic IOLs, BSA was detected at a depth of 38 +/- 7.4 microm after 1 day, followed by an increase to 192.7 +/- 16.2 microm after 14 days. Despite the penetration depth into the hydrophilic acrylic IOLs, quantitative results confirmed that PMMA and hydrophilic acrylic deposited significantly less BSA (mean 278.3 +/- 41.7 ng and 296.5 +/- 33.1 ng, respectively) than silicone IOLs (mean 392.6 +/- 37.6 ng) (P<.05).

CONCLUSIONS

Silicone and PMMA IOL materials showed BSA sorption near the lens surface only, while BSA penetrated deep into the hydrophilic acrylic IOL matrix. Combining the qualitative CLSM method and quantitative radiolabeling technique provided detailed information on protein interactions with implantable biomaterials.

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.

Long-term effect of optic edge design in a silicone intraocular lens on posterior capsule opacification

PURPOSE

To compare the posterior capsule opacification (PCO) inhibiting effect of the round anterior and sharp posterior optic edge profile of the Clariflex silicone intraocular lens (IOL) [AMO Inc, Santa Ana, California, USA] with that of the double-round edge profile of the SI40 (Phacoflex; AMO Inc, Santa Ana, California, USA) silicone IOL over a period of three years.

DESIGN

Prospective, randomized, double-masked, bilateral clinical trial.

METHODS

The study took place at the Department of Ophthalmology, Medical University of Vienna, Austria. Fifty-two patients with age-related cataracts (104 eyes) were included in the study. Each patient received an SI40 IOL (round edges) in one eye and a Clariflex IOL with OptiEdge (sharp posterior optic edge) in the other eye. Follow-up examinations were at one week, one month, six months, and one, two, and three years. Digital retroillumination images were taken of each eye. The amount of PCO was subjectively assessed with the slit-lamp and objectively assessed by automated image analysis software (the computer program Automated Quantification of After-Cataract [AQUA]; Vienna, Austria) one, two, and three years after surgery.

RESULTS

The Clariflex lens showed markedly less PCO at one, two, and three years after surgery. The mean AQUA PCO score was 1.39 for the SI40 and 0.56 for the Clariflex lens after one year, estimated at 1.64 and 0.57 after two years, and at 2.04 and 0.64, respectively, after three years (scale zero to 10; P < .001). The Nd:YAG laser capsulotomy rate was far higher in the SI40 group (Five cases vs one case at three years).

CONCLUSIONS

The sharp posterior optic edge profile of the Clariflex silicone IOL led to marked and consistently less PCO than the round-edged SI40 IOL one, two, and three years after surgery.

Quantitative Analysis of Posterior Capsule Opacification of Hydrophobic Acrylic Intraocular Lenses

Posterior capsule opacification (PCO) remains a common complication of modern cataract surgery, although both modification of materials used and changes in the intraocular lens (IOL) optic edge design have helped to decrease its incidence slightly. Recently, various kinds of quantitative methods have been developed for measuring PCO. The purpose of this study was to compare the quantitative analysis of PCO between different types of IOL designs. Patients enrolled in the study had age-related cataract and underwent uneventful cataract surgery and implantation of either the AcrySof MA30BA (Alcon) or the Sensor AR40e (AMO), which are differently designed hydrophobic acrylic IOLs with a sharp-edged optic design. Postoperative examination was performed at 6 months. Retroillumination photographs of each eye were obtained, and the degree of PCO was assessed using the Evaluation of Posterior Capsule Opacification (EPCO) system. Grade 1 PCO was noted in both the MA30BA and the AR40e groups. There was no significant difference in the mean PCO score between the MA30BA and AR40e groups. Although the sharp-edged optic designs of both IOLs might similarly inhibit PCO at 6 months, a long-term follow-up period is needed to determine if any PCO differences occur between these 2 hydrophobic acrylic IOLs.

Posterior capsular opacification in diabetic and nondiabetic canine patients following cataract surgery

Posterior capsular opacification (PCO) is the most common postoperative complication of contemporary cataract surgery. Limited information is available regarding PCO formation and factors that influence PCO development in the dog. Two hundred sixty-five eyes (144 from diabetic dogs and 121 from dogs with breed-related cataracts) were prospectively evaluated for PCO formation for up to 12 months postoperatively. The mean age of all dogs in the study was 7.77 years and diabetic dogs were significantly older than dogs with breed-related cataracts. There were 73 males (61 neutered, 12 intact) and 74 females (70 neutered, 4 intact) in the study. Statistical analysis was performed based on age, breed/size, gender, stage of cataract at the time of surgery, PCO score at each time point, breed-related vs. diabetic cataract, right eyes compared to left eyes, and presence/absence of uveitis. Age and gender did not significantly influence PCO formation. Small and medium-sized breeds developed significantly more PCO in comparison to the large/giant breeds at 2 weeks and 2-4 months postoperatively, but the differences were not significant at later time points. There was an overall significant increase in PCO formation in eyes with early immature cataracts when compared to other stages of cataract up to 4 months postoperatively but not at later time points. There were no statistical differences in PCO score at 6 months or at 1 year postoperatively in eyes with breed-related and diabetic cataracts. Right eyes did not differ from left eyes in PCO score. PCO score significantly increased over time in breed-related and diabetic groups and in the overall population. No difference was found in the degree of PCO formation in eyes with inflammation prior to or after surgery compared with those without inflammation. In summary, age, gender, presence of inflammation, and cause of cataract (breed-related vs. diabetes mellitus) do not influence the development of PCO in canine cataract dogs. Small and medium-sized breeds develop significant PCO earlier than larger breeds. It is important to note that all eyes from all dogs in this study developed PCO in a time dependent manner.

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.

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.

Lens epithelial cell ongrowth: Comparison of 6 types of hydrophilic intraocular lens models

PURPOSE

To compare the ongrowth of lens epithelial cells (LECs) on the anterior surface of 6 different hydrophilic intraocular lenses (IOLs).

SETTING

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

METHODS

Six models of hydrophilic IOLs were compared in this prospective study: Visionflex A-100 (Distra Softcryl), Rayner Centerflex 570H (Rayner), Collamer CC4204BF-IOL (Staar), Injectacryl F 3000 (Distra), Hydroview H60M (Bausch & Lomb), and MemoryLens (ORC). Postoperative biomicroscopic examinations were performed 1, 3, 7, 30, 90, 180, and 365 days after surgery. Lens epithelial cells in each quadrant of the anterior capsule-free lens surface were graded. The product with the highest density and the number of quadrants with this density were used to measure LEC ongrowth.

RESULTS

The Hydroview and Visionflex IOLs showed significantly more LECs than the other IOLs starting on day 7 after surgery (P < .028). There was a statistically significant difference in LEC ongrowth on the Memory IOL compared with all other IOLs from day 30 onward (P < .001). The Rayner, Collamer and Injectacryl IOLs had the fewest LECs on the anterior surface compared with all other IOLs from day 7 until the final examination.

CONCLUSIONS

The findings show that LEC ongrowth on the IOL surface is material dependent. The findings suggest that the material of the recently developed hydrophilic IOLs induces less LEC ongrowth than older models.

Nd:YAG capsulotomy rates after use of the AcrySof acrylic three piece and one piece intraocular lenses

BACKGROUND/AIM

Acrylic lens size and shape may influence the rate of posterior capsule opacification (PCO) and need for Nd:YAG capsulotomy. The aim of this study is to compare the Nd:YAG capsulotomy rate of the three piece acrylic/PMMA AcrySof MA series lens with the one piece acrylic AcrySof SA series lens.

METHODS

434 eyes of 329 patients who had cataract extraction and implantation of one of four types of intraocular lenses (IOLs) were evaluated for rate of Nd:YAG capsulotomy. 176 eyes received the acrylic AcrySof MA30AC IOL, 71 eyes the acrylic AcrySof MA60AC IOL, 45 eyes the acrylic AcrySof SA30AL IOL, and 142 eyes the acrylic AcrySof SA60AT IOL.

RESULTS

The rates of Nd:YAG capsulotomy with the three piece IOL (MA30AC/MA60AC) and the one piece IOL (SA30AL/SA60AT) were 1.2% and 2.1% at 6 months, 2.8% and 5.9% at 12 months, and 3.6% and 7.5% at 24 months, respectively. The incidence of Nd:YAG capsulotomy was higher in patients who received the one piece IOL (p=0.01, log rank test). There was no difference in Nd:YAG capsulotomy rates when comparing lens optic size, age, sex, history of pars plana vitrectomy, and diabetes mellitus.

CONCLUSIONS

This study shows a greater incidence of Nd:YAG capsulotomy in patients who receive one piece acrylic AcrySof lenses when compared to those who receive three piece acrylic AcrySof lenses.

Prospective evaluation of phacoemulsification in adults younger than 50 years

PURPOSE

To evaluate intraoperative performance and long-term outcome of phacoemulsification in patients younger than 50 years.

SETTING

Iladevi cataract and IOL Research Centre, Ahmedabad, India.

METHODS

A prospective observational study was conducted comprising 54 patients (35 men and 19 women) under age 50 who had phacoemulsification. Preoperative evaluation included specular microscopy. Phacoemulsification with implantation of an AcrySof MA30BA intraocular lens (IOL) was performed. Intraoperatively, peripheral extension of capsulorhexis, intraoperative posterior capsule opacification (PCO; plaque), and serious complications (eg, posterior capsule rupture, vitreous loss) were noted. Postoperatively, endothelial cell loss, postoperative PCO, neodymium:YAG (Nd:YAG) laser posterior capsulotomy rate, and best corrected visual acuity (BCVA) were assessed for 3 years. Patients with intraoperative PCO were analyzed separately.

RESULTS

Mean patient age was 42.7 years +/- 5.2 SD (men) and 43.1 +/- 3.25 years (women). Continuous curvilinear capsulorhexis was achieved in 49 patients (90.7%). Intraoperative PCO was present in 14 (25.92%) patients. An Nd:YAG laser posterior capsulotomy was performed in 4 patients (28.5%). Posterior capsule rupture leading to vitreous loss occurred in 1 patient (1.85%). At 3-year follow-up, endothelial cell loss was 5.9%. Postoperative PCO developed in 8 patients (22.2%), and Nd:YAG laser posterior capsulotomy was performed in 5 patients (13.8%). The BCVA was > or = 20/40 in 47 patients (94%).

CONCLUSION

Young patients pose a challenge in creating a capsulorhexis and display significant incidence of intraoperative and postoperative PCO.

Long-term effect of optic edge design in an acrylic intraocular lens on posterior capsule opacification

PURPOSE

To compare the posterior capsule opacification (PCO) inhibiting effect of the sharp posterior optic edge design of the Sensar OptiEdge AR40e intraocular lens (IOL) with that of the double-round edge design of the Sensar AR40 IOL over a period of 3 years.

SETTING

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

METHODS

Fifty-three patients with bilateral age-related cataract (106 eyes) were included in this randomized prospective bilateral patient- and examiner-masked clinical trial with intraindividual comparison. Each study patient had cataract surgery in both eyes and received a Sensar AR40 IOL (anterior and posterior round optic edges) in 1 eye and a Sensar OptiEdge AR40e IOL (round anterior and sharp posterior optic edge) in the other eye. Follow-up examinations were at 1 week, 1 and 6 months, and 1, 2, and 3 years. Digital retroillumination images were taken of each eye. The amount of PCO was assessed subjectively at the slitlamp and objectively using automated image-analysis software (AQUA) 1, 2, and 3 years after surgery.

RESULTS

The sharp-edged AR40e lens showed significantly less regeneratory and fibrotic PCO 1, 2, and 3 years after surgery. The mean AQUA PCO score was 2.18 for the AR40 and 1.00 for the AR40e lens after 1 year; 2.94 and 1.56 after 2 years, and estimated at 3.13 and 1.77, respectively, after 3 years (scale 0 to 10; P<.001). The neodymium:YAG laser capsulotomy rate was significantly higher in the AR40 group. The AR40e lens also led to less peripheral fibrotic PCO. There was no significant difference in complaints concerning edge glare between the groups.

CONCLUSION

Compared with the AR40 IOL, the sharp posterior optic edge design of the Sensar OptiEdge AR40e IOL led to significantly less PCO 1, 2, and 3 years postoperatively. In contrast with most past studies on PCO-preventative factors, this study varied only 1 parameter, namely the optic edge design, and the main outcome measure (PCO) was assessed with an objective image-analysis system.

Comparison of the Long-term Clinical Results of Hydrophilic and Hydrophobic Acrylic Intraocular Lenses

This study was performed to compare the incidence of posterior capsular opacity (PCO) and refractive errors between hydrophilic (ACR6D, Corneal) and hydrophobic (MA60BM, AcrySof) acrylic intraocular lenses (IOLs) over a 3-year follow-up after phacoemulsification surgery. The patients with AcrySof implanted in one eye and Corneal in the other eye were categorized as Group 1 (n=28), while those with one or both eyes implanted with IOLs of the same kind were categorized as Group 2 (AcrySof, n=90; Corneal, n=95). Refractive errors were evaluated at 3 months and 3 years postoperatively. The incidence of visually significant PCO was investigated 3 years postoperatively. Postoperative refractive values at 3 months were not significantly different between the two groups. However, refractive values at 3 years were significantly different between two IOLs in both groups [AcrySof -0.37+/-0.43D, Corneal -0.62+/-0.58D in Group 1 (p=0.04); AcrySof -0.38+/-0.52, Corneal -0.68+/-0.54 in Group 2 (p<0.01)]. The incidence of visually significant PCO was 14% and 32% in Group 1, and 13% and 28% in Group 2, for the AcrySof and Corneal implants, respectively. The incidence of visually significant PCO of hydrophilic acrylic IOLs was higher than that of hydrophobic acrylic IOLs in the 3-year follow-up. The postoperative 3-year refractive value of Corneal showed myopic shift.

Intraoperative peripheral anterior capsulotomy to prevent early postoperative capsular block syndrome

We describe a new surgical technique, intraoperative peripheral anterior capsulotomy (IPAC), to prevent early postoperative capsular block syndrome (CBS). Eighty consecutive patients (80 eyes) had phacoemulsification and intraocular lens implantation with IPAC in the presence of a small (4.5 to 5.0 mm) anterior continuous curvilinear capsulorhexis (CCC). Patients were followed for a mean of 16 months (range 6 to 24 months), and none developed CBS or other complications. Our series suggests that IPAC may be an alternative to prevent CBS in high-risk eyes, including those with a small anterior CCC or ophthalmic viscosurgical device material trapped in the capsular bag. This surgical technique is safe, effective, inexpensive, and easy to perform.

The Auckland Cataract Study: 2 year postoperative assessment of aspects of clinical, visual, corneal topographic and satisfaction outcomes

AIM

To assess clinical, visual, computerised corneal topographic, and subjective satisfaction with visual acuity, in a cohort of subjects 2 years after phacoemulsification surgery in a public hospital in New Zealand.

METHODS

Prospective study of a representative sample of 97 subjects (20%) randomly selected from 480 subjects in the original Auckland Cataract Study (ACS) cohort. The clinical assessment protocol was identical to the ACS and included an extensive questionnaire to enable direct comparisons to be made between the two groups.

RESULTS

The study population was predominantly female (66%) with a mean age of 76.3 (SD 9.9) years. New systemic and ocular disease affected 18.4% and 10.3% of subjects respectively, and 10.3% required referral to either a general practitioner (2.1%) or ophthalmologist (8.2%). Mean best spectacle corrected visual acuity (BSCVA) was 0.2 (0.2) logMAR units (6/9 Snellen equivalent), with mean spherical equivalent -0.37 (1.01) dioptres (D) and astigmatism -1.07 (0.70) D 2 years postoperatively, compared to mean BSCVA 0.1 (0.2) logMAR units (6/7.5 Snellen equivalent), spherical equivalent -0.59 (1.07) D, and astigmatism -1.14 (0.77) D 4 weeks after surgery. 94.9% of subjects retained a BSCVA of 6/12 or better, irrespective of pre-existing ocular disease. The overall posterior capsule opacification (PCO) rate was 20.4% and this was visually insignificant in all but 3.1% of eyes that had already undergone Nd:YAG posterior capsulotomy. Orbscan II elevation technology demonstrated corneal stability 2 years after uncomplicated phacoemulsification. Although corneal astigmatism was eliminated in approximately half of the subjects 1 month postoperatively, astigmatism showed a tendency to regress towards the preoperative level with local corneal thickening at the site of incision 2 years after cataract surgery. Of fellow eyes, 61.2% had undergone cataract surgery. Overall, 75.3% of subjects were moderately to very satisfied with their current level of visual acuity.

CONCLUSION

Two years after cataract surgery subjects are generally satisfied with their current level of vision and distance BSCVA is 6/12 or better in the majority of eyes. Although only a minority of eyes develop sufficient PCO to require capsulotomy 10.3% of eyes develop new vision threatening ocular pathology.

Neodymium:YAG laser posterior capsulotomy after implantation of AcrySof intraocular lenses

PURPOSE

To report the incidence of neodymium:YAG (Nd:YAG) laser posterior capsulotomy after phacoemulsification and implantation of AcrySof (Alcon) intraocular lenses (IOLs).

SETTING

Private practice, Wolfe Clinic, Marshalltown, Iowa, USA.

METHODS

A retrospective diagnosis and procedure code review of 12419 consecutive cases having phacoemulsification and AcrySof IOL implantation from January 1995 through December 2002 was performed. The outcome parameter was the incidence of Nd:YAG laser posterior capsulotomies.

RESULTS

An Nd:YAG laser posterior capsulotomy was performed in 763 (6.1%) of the 12419 cases. The incidence of posterior capsulotomy was approximately 1% at 1 year, increasing in linear fashion by approximately 1% to 2% per year.

CONCLUSIONS

The Nd:YAG laser posterior capsulotomy rate after implantation of AcrySof IOLs was relatively low; the cumulative rate was approximately 1% to 2% new cases per year over a 7-year period, with a plateau suggested at year 6.

Anterior capsule relationship of the AcryS of intraocular lens optic and posterior capsule opacification

OBJECTIVE

To evaluate the relationship of the anterior capsule and the AcrySof MA30BA intraocular lens (IOL) and its impact on the development of central posterior capsule opacification (PCO).

DESIGN

Prospective, randomized, controlled trial.

PARTICIPANTS

Two hundred two patients with senile cataracts received an AcrySof IOL between July and December 1998 at Iladevi Cataract and IOL Research Center, Ahmedabad, India.

INTERVENTION

Patients were randomized prospectively to receive 1 of the 3 possibilities of anterior capsule and IOL optic relationship: group 1, total anterior capsule cover (360 degrees ) of the optic; group 2, no anterior capsule cover (360 degrees ) of the optic; group 3, partial anterior capsule cover (<360 degrees ) of the optic. After surgery, slit-lamp video photography was performed every 6 months for 3 years. Analyses of variance and chi-square tests were used to compare treatment groups.

MAIN OUTCOME MEASURES

Incidence of PCO in the 3 groups. The posterior capsule was divided into 3 zones: peripheral, central 3 mm, and midperipheral (the space between the peripheral and the central zones).

RESULTS

The average follow-up was 35.3 +/- 1.52 months in all the groups. At 3 years, the rate of central PCO was 6.4% in group 1, 7.1% in group 2, and 5.9% in group 3 (P = 0.9). Midperipheral PCO was present in 24.2% in group 1, 16% in group 2, and 20.6% in group 3 (P = 0.9). Peripheral PCO was seen in 100% of patients in all groups. The neodynium:yttrium-aluminum-garnet laser (Nd:YAG) posterior capsulotomy rate was 0% in all groups.

CONCLUSIONS

There was no significant difference in the incidence of development of central PCO among the 3 groups. No patient experienced central PCO that required Nd:YAG capsulotomy. When using the AcrySof IOL model MA30BA, the relationship of the anterior capsule and the IOL does not seem to be a factor that relates to the development of central PCO.

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.

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.

Material Properties of Various Intraocular Lenses in an Experimental Study

INTRODUCTION

With the recent introduction of small-incision cataract surgery, requirements for intraocular lens (IOL) flexibility, strength and hydrophilicity have rapidly evolved. The IOL surface, however, remains a critical factor influencing uveal biocompatibility.

PURPOSE

To objectively quantify factors of material properties of various IOLs using contact angle measurements, differential scanning calorimetry, dynamic-mechanical measurements and scanning electron microscopy.

MATERIAL AND METHODS

In our study, 17 currently available IOLs were investigated using contact angle measurements to assess hydrophilicity and biocompatibility, as well as differential scanning calorimetry for the estimation of glass transition temperature. Mechanical capacity and flexibility were investigated using dynamic-mechanical measurements. Additional analysis of the IOL surface was performed using scanning electron microscopy.

RESULTS

The contact angle measurements of the studied IOLs revealed similar values within each group. The silicone IOLs had values between 106 and 119 degrees. The PMMA IOLs were found to have a narrower range of values, between 73.2 and 75.5 degrees. Lenses made of hydrogel had values between 59.2 and 69.1 degrees. The heparin-modified surface showed the lowest contact angle of 56.5 degrees. The glass transition temperature was determined by dynamic differential scanning calorimetry. The resulting values were between 118.8 and 113.5 degrees C for PMMA IOLs, 15.5 and 14.0 degrees C for acrylic IOLs, and -91.7 and -119.6 degrees C for silicone IOLs. The dynamic-mechanical measurements revealed that PMMA lenses manifested characteristics similar to glass, whereas silicone lenses had characteristics similar to rubber. Acrylic lenses were between rubber and glass. Scanning electron microscopy revealed smooth dispersion of fibrin on hydrophobic IOLs and a relative lack of fibrin adhesion on hydrophilic materials.

CONCLUSION

These results demonstrate that material properties of various IOL materials are consistent within classes of IOL materials. This suggests that the intraoperative and postoperative behavior of an IOL is predictable and related to its composition, thus allowing surgeons to choose IOLs more appropriate for different surgical situations and individual patient characteristics.

Hydrophobic acrylic versus heparin surface-modified polymethylmethacrylate intraocular lens: a biocompatibility study

BACKGROUND

The implant of intraocular lenses (IOLs) following cataract surgery induces a foreign-body reaction to the IOL and a response on the part of the lens epithelial cells (LECs). The purpose of this study was to compare these aspects after the implantation of two different IOL materials.

METHODS

Thirty-six cataract patients were randomised to receive two different foldable lens: an acrylic hydrophobic IOL (Acrysof MA30BA) and a heparin surface-modified (HSM) polymethylmethacrylate IOL (Pharmacia & Upjohn 809C) after phacoemulsification. Slit-lamp biomicroscopy with specular technique was used to assess the inflammatory cell adhesion on the anterior IOL surface, anterior capsule opacification (ACO) and membrane growth from the rhexis edge at 7, 30, 90, 180 and 360 days after surgery.

RESULTS

The 809C group showed a higher percentage of patients with slight inflammatory cell adhesion on the anterior cell surface and a higher small cellular density during the whole follow-up period. The epithelioid cell response was greater in the 809C group than the Acrysof group but the difference between the two groups was not statistically significant. The ACO increased during the follow-up in both groups but was significantly higher in the 809C group.

CONCLUSION

Acrysof lenses are more biocompatible than HSM IOLs, showing a lower grade of inflammatory cell adhesion and ACO. The implantation of these lenses may be particularly indicated in patients with pathologies predisposing to blood-aqueous barrier damage.

A comparison of Nd:YAG capsulotomy rate in two different intraocular lenses: AcrySof and Stabibag

PURPOSE

To evaluate the incidence of posterior capsule opacification after implantation of two different intraocular lenses (IOLs), AcrySof and Stabibag, by comparing the neodymium:YAG (Nd:YAG) laser capsulotomy rates.

METHODS

The medical records of 596 patients (705 eyes) who underwent phacoemulsification and posterior chamber IOL implantation using either AcrySof (n = 335) or Stabibag (n = 370) IOLs during a 1-year (1999) period were reviewed. Eyes with secondary cataract, combined procedures or operative complications, such as capsule tears, were excluded from the study. The subjects' age, sex, surgeon (two surgeons), and time for Nd:YAG laser capsulotomy were recorded.

RESULTS

The mean follow-up was 23 months in both IOL groups. There were no statistically significant differences within the two IOL groups regarding sex distribution or surgeon. The mean age in the AcrySof group was 77.0 years compared to 79.2 years in the Stabibag group (p = 0.001). Nd:YAG laser capsulotomy was performed in 7.6% of patients in the Stabibag group compared to 2.7% in the AcrySof group (i.e. at a significantly higher rate) (p = 0.004). Survival analyses demonstrated that age and type of IOL were the only independent predictors of the incidence of capsulotomy.

CONCLUSIONS

This study shows that the frequency of eyes with posterior capsule opacification needing capsulotomy was significantly higher in eyes with Stabibag IOLs compared to eyes with AcrySof IOLs.

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.

Effect of an acrylic intraocular lens with a sharp posterior optic edge on posterior capsule opacification

PURPOSE

To compare the posterior capsule opacification (PCO) inhibiting effect of the sharp posterior optic edge design of the Sensar OptiEdge AR40e intraocular lens (IOL) (Allergan Surgical) with that of the round-edged design of the Sensar AR40 IOL. Setting Department of Ophthalmology, University of Vienna, Vienna, Austria.

METHODS

This prospective randomized patient- and examiner-masked study comprised 106 eyes of 53 patients with bilateral age-related cataract. Each patient had cataract surgery in both eyes and received an AR40 IOL in 1 eye and an AR40e IOL in the other eye. Postoperative examinations were at 1 week, 2 and 6 months, and 1 year. Digital slitlamp and digital retroillumination images of each eye were taken. The amount of PCO was assessed subjectively at the slitlamp and objectively using automated image-analysis software.

RESULTS

The AR40e group had significantly less regeneratory and fibrotic PCO 1 year after surgery. The mean automated image-analysis software PCO score (scale 0 to 10) was 2.19 in the AR40 group and 1.10 in the AR40e group (P <.001). The AR40e group had less peripheral fibrotic PCO. There was no significant difference in patient-reported edge glare between the 2 IOL groups.

CONCLUSIONS

The sharp-edged design of the Sensar OptiEdge AR40e IOL led to significantly less PCO than the round-edged AR40 IOL 1 year postoperatively.