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

Posterior capsular opacification and Nd:YAG capsulotomy rates in patients implanted with square-edged and non-square-edged intraocular lenses in manual small-incision cataract surgery: A randomized controlled study

Purpose

To study posterior capsular opacification (PCO) and neodymium-doped yttrium aluminum garnet (Nd:YAG) capsulotomy rates in patients implanted with square-edged and non-square-edged intraocular lenses (IOLs) in manual small-incision cataract surgery (MSICS).

Setting

Tertiary eye care center.

Design

Prospective, comparative, and randomized controlled study.

Methods

This study included patients with senile cataracts scheduled for MSICS and IOL implantation. One eye of each patient was randomized to the implantation of square-edged (S group) or non-square-edged IOL (NSQ group). An independent observer analyzed PCO at 6, 12, 18, and 24 months under slit-lamp illumination.

Results

A total of 104 eyes were included in this study. The mean age of the participants in the two groups was 63.2 (±8.2) years, and there were 65 (62.5%) men and 39 women (37.5%). The mean best-corrected visual acuity (BCVA) values at 6, 12, and 18 months were 0.157 (±0.10), 0.11 (±0.12), and 0.12 (±0.11), respectively, in the S group and 0.17 (±0.10), 0.17 (±0.12), and 0.20 (±0.17), respectively, in the NSQ group. At 12 (P = 0.03) and 18 months (P = 0.01) follow-up, the BCVA of the S group was significantly better than that of the NSQ group. Four eyes in the NSQ group and one eye in the S group required Nd:YAG.

Conclusion

Evaluation of PCO and Nd:YAG capsulotomy rates showed that the 360° square of the posterior IOL edge plays a role in the prevention of PCO. Owing to the low cost of the material and the easy availability of IOLs manufactured from it, square-edged IOL has a definite role in the prevention of PCO in MSICS.

"Comparing outcomes of advanced nurse practitioners to ophthalmologists performing posterior YAG capsulotomy, a six-year study of 6308 eyes"

PURPOSE

To primarily report the baseline characteristics and visual acuity (VA) outcomes of advanced nurse practitioners (ANP) compared to ophthalmologists following YAG posterior capsulotomy (YAGPC). We secondarily looked to characterise the risk factors that lead to a repeated YAGPC.

METHOD

Retrospective consecutive case series of 6,308 eyes attending the Birmingham and Midlands Eye Centre.

RESULTS

ANPs performed 33.1% of YAGPC compared to 66.9% ophthalmologists. Compared to ophthalmologists, ANPs performed YAGPC in lower proportion of patients with ocular co-morbidities (p < 0.001) and had lower proportion of patients requiring further YAGPC compared to ophthalmologists (p < 0.001). Median pre, post-operative and LogMAR gain in VA of 0.48 (IQR 0.30-0.78), 0.18 (IQR 0.10-0.40) and 0.30 (0.08-0.48) LogMAR units, respectively. Multivariate regression showed that ANPs had a significantly lower rate of repeat YAGPC compared to ophthalmologists even when adjusting for age, ethnicity, training grade and ocular co-morbidities. No difference in visual outcomes was found between operator grade and ethnicity on multivariate analysis.

CONCLUSION

YAGPC leads to excellent visual outcomes. ANPs can deliver safe and effective YAGPC.

Intraocular lens optic edge design for the prevention of posterior capsule opacification after cataract surgery

BACKGROUND

Posterior capsule opacification (PCO) is a clouding of the posterior part of the lens capsule, a skin-like transparent structure, which surrounds the crystalline lens in the human eye. PCO is the most common postoperative complication following modern cataract surgery with implantation of a posterior chamber intraocular lens (IOL). The main symptoms of PCO are a decrease in visual acuity, 'cloudy', blurred vision and reduced contrast sensitivity. PCO is treated with a neodymium:YAG (Nd:YAG) laser to create a small opening in the opaque capsule and regain a clear central visual axis. This capsulotomy might cause further ocular complications, such as raised intraocular pressure or swelling of the central retina (macular oedema). This procedure is also a significant financial burden for health care systems worldwide. In recent decades, there have been advances in the selection of IOL materials and optimisation of IOL designs to help prevent PCO formation after cataract surgery. These include changes to the side structures holding the lens in the centre of the lens capsule bag, called IOL haptics, and IOL optic edge designs.

OBJECTIVES

To compare the effects of different IOL optic edge designs on PCO after cataract surgery.

SEARCH METHODS

We searched CENTRAL, Ovid MEDLINE, Ovid Embase, Latin American and Caribbean Health Sciences Literature Database (LILACS), the ISRCTN registry, ClinicalTrials.gov and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) up to 17 November 2020.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that compared different types of IOL optic edge design. Our prespecified primary outcome was the proportion of eyes with Nd:YAG capsulotomy one year after surgery. Secondary outcomes included PCO score, best-corrected distance visual acuity (BCDVA) and quality of life score at one year. Due to availability of important long-term data, we also presented data at longer-term follow-up which is a post hoc change to our protocol.

DATA COLLECTION AND ANALYSIS

We used standard methods expected by Cochrane and the GRADE approach to assess the certainty of the evidence.

MAIN RESULTS

We included 10 studies (1065 people, 1834 eyes) that compared sharp- and round-edged IOLs. Eight of these studies were within-person studies whereby one eye received a sharp-edged IOL and the fellow eye a round-edged IOL. The IOL materials were acrylic (2 studies), silicone (4 studies), polymethyl methacrylate (PMMA, 3 studies) and different materials (1 study). The studies were conducted in Austria, Germany, India, Japan, Sweden and the UK. Five studies were at high risk of bias in at least one domain. We judged two studies to be at low risk of bias in all domains. There were few cases of Nd:YAG capsulotomy at one year (primary outcome): 1/371 in sharp-edged and 4/371 in round-edged groups. The effect estimate was in favour of sharp-edged IOLs but the confidence intervals were very wide and compatible with higher or lower chance of Nd:YAG capsulotomy in sharp-edged compared with round-edged lenses (Peto odds ratio (OR) 0.30, 95% CI 0.05 to 1.74; I² = 0%; 6 studies, 742 eyes). This corresponds to seven fewer cases of Nd:YAG capsulotomy per 1000 sharp-edged IOLs inserted compared with round-edged IOLs (95% CI 9 fewer to 7 more). We judged this as low-certainty evidence, downgrading for imprecision and risk of bias. A similar reduced risk of Nd:YAG capsulotomy in sharp-edge compared with round-edge IOLs was seen at two, three and five years but as the number of Nd:YAG capsulotomy events increased with longer follow-up this effect was more precisely measured at longer follow-up: two years, risk ratio (RR) 0.35 (0.16 to 0.80); 703 eyes (6 studies); 89 fewer cases per 1000; three years, RR 0.21 (0.11 to 0.41); 538 eyes (6 studies); 170 fewer cases per 1000; five years, RR 0.21 (0.10 to 0.45); 306 eyes (4 studies); 331 fewer cases per 1000. Data at 9 years and 12 years were only available from one study. All studies reported a PCO score. Four studies reported the AQUA (Automated Quantification of After-Cataract) score, four studies reported the EPCO (Evaluation of PCO) score and two studies reported another method of quantifying PCO. It was not possible to pool these data due to the way they were reported, but all studies consistently reported a statistically significant lower average PCO score (of the order of 0.5 to 3 units) with sharp-edged IOLs compared with round-edged IOLs. We judged this to be moderate-certainty evidence downgrading for risk of bias. The logMAR visual acuity score was lower (better) in eyes that received a sharp-edged IOL but the difference was small and likely to be clinically unimportant at one year (mean difference (MD) -0.06 logMAR, 95% CI -0.12 to 0; 2 studies, 153 eyes; low-certainty evidence). Similar effects were seen at longer follow-up periods but non-statistically significant data were less fully reported: two years MD -0.01 logMAR (-0.05 to 0.02); 2 studies, 311 eyes; three years MD -0.09 logMAR (-0.22 to 0.03); 2 studies, 117 eyes; data at five years only available from one study. None of the studies reported quality of life. Very low-certainty evidence on adverse events did not suggest any important differences between the groups.

AUTHORS' CONCLUSIONS

This review provides evidence that sharp-edged IOLs are likely to be associated with less PCO formation than round-edged IOLs, with less Nd:YAG capsulotomy. The effects on visual acuity were less certain. The impact of these lenses on quality of life has not been assessed and there are only very low-certainty comparative data on adverse events.

Evaluation of Nd:YAG Laser Capsulotomy Rates in a Real-Life Population

Objective

The objective of this study was to assess the rate of posterior capsule opacification (PCO), under “real-life” conditions, as measured by rates of Nd:YAG laser intervention, rather than from a controlled study from which patients with conditions predisposing to PCO have been excluded.

Methods and Analysis

This was a retrospective, multicenter study in an unselected consecutive cohort of patients undergoing surgery for senile cataract. Patients aged 18 years and older, previously implanted with the CT LUCIA 611P IOL, were contacted at 12, 18 and 24 months to ascertain if they had received Nd:YAG laser treatment. There was an additional assessment at 36 months at the Austrian centre.

Results

A total of 200 patients were recruited at two centers. Laser capsulotomy rates were 4.5% at 1 year and 10% by year 2 and 12% by year 3. Three Nd:YAG capsulotomies, carried out at other external centers, were performed for reasons other than PCO, including astigmatism, epiretinal membrane and ARMD. If these patients are excluded, the true rate of Nd:YAG carried out for PCO at 1 year was 3.5% and at 2 years was 8.5%.

Conclusion

It is critical to ensure that Nd:YAG capsulotomies are being performed only for the correct clinical reason. Carrying out unnecessary procedures places the patient at risk of adverse events, is a cost to the healthcare system, and is likely to have no direct visual benefit for the patient. In PCO studies, it should be a requirement to document the fibrosis grade to confirm that Nd:YAG capsulotomy was correctly indicated.

Intraocular Lens Power, Myopia, and the Risk of Nd:YAG Capsulotomy after 15,375 Cataract Surgeries

The present study estimated the 5-year cumulative probability of Nd:YAG laser posterior capsulotomy according to the diopter power of implanted hydrophobic acrylic intraocular lenses (IOLs). Data were retrospectively collected of 15,375 eyes having cataract surgery and in-the-bag implantation of hydrophobic acrylic monofocal IOLs at the Ophthalmology Unit of Kymenlaakso Central Hospital, Kotka, Finland between the years 2007 and 2016. The cumulative probability of Nd:YAG capsulotomy was calculated by Kaplan-Meier estimates, and potential risk factors were analyzed using the Cox proportional hazards model. The 5-year cumulative probability of Nd:YAG capsulotomy after cataract surgery was 27.4% (95% confidence interval (CI) 22.9-32.6%) for low-diopter (5-16.5 D) IOLs, 14.6% (13.8-15.5%) for mid-diopter (17-24.5 D) IOLs, and 13.6% (11.7-15.6%) for high-diopter (25-30 D) IOLs. A multivariate Cox regression analysis showed that low-diopter IOLs (HR 1.76; 95% CI 1.38-2.25; p < 0.001) were associated with an increased risk of Nd:YAG capsulotomy compared to mid-diopter IOLs over the follow-up period after accounting for other predictors. Real-world evidence shows that low-diopter IOLs are associated with significantly higher risk of Nd:YAG capsulotomy within five years following implantation. Estimation should help in evaluating the risks of cataract surgery in myopic eyes.

Posterior Capsule Opacification With Two Hydrophobic Acrylic Intraocular Lenses: 3-Year Results of a Randomized Trial

PURPOSE

To compare the incidence and intensity of posterior capsule opacification (PCO) and neodymium-yttrium-aluminum-garnet (Nd:YAG) capsulotomy rates between 2 similar open-loop single-piece hydrophobic acrylic intraocular lenses (IOLs) that differ in the proprietary material characteristics and design features, over a period of 3 years.

DESIGN

Randomized, prospective, patient- and examiner-masked clinical trial with intraindividual comparison.

METHODS

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

PATIENT POPULATION

Eighty patients (160 eyes) had bilateral cataract surgery and received a Vivinex XY1 IOL in 1 eye and an AcrySof SN60WF IOL in the other eye.

OBSERVATION PROCEDURES

Follow-up examinations were performed 3 years after surgery. Digital retroillumination images were taken of each eye. The amount of PCO (score: 0-10) was assessed subjectively at the slit lamp and objectively using automated image analysis software (AQUA).

MAIN OUTCOME MEASURE

PCO score (scale, 0-10).

RESULTS

The mean objective PCO score of the Vivinex XY1 IOLs was 0.9 ± 0.8 compared to the PCO score of 1.4 ± 1.1 for the AcrySof SN60WF IOLs (P < .001). Three years postoperatively, 11.4% of patients had an Nd:YAG capsulotomy in the Vivinex XY1 eye and 18.6% had a capsulotomy in the AcrySof SN60WF eye (P = .23).

CONCLUSION

The new hydrophobic acrylic Vivinex XY1 IOL showed significantly lower PCO rates and lower YAG rates compared to the AcrySof SN60WF IOL. The interaction of various factors such as hydrophobic material, smooth optic surface, and sharp posterior optic edge plays a key role in PCO development.

Posterior capsule opacification and Nd:YAG laser rates with two hydrophobic acrylic single-piece IOLs

OBJECTIVES

To evaluate the development of posterior capsule opacification (PCO) and Nd:YAG capsulotomy rates following implantation of two hydrophobic acrylic IOLs.

METHODS

In a randomized, controlled trial, 80 patients with bilateral senile cataract were implanted with the hydrophobic acrylic single-piece intraocular Lenses (IOLs) EyeCee One in one eye and iMics1 in the other. Outcomes of 39 patients (78 eyes) were evaluated after 3 years. Automated Quantification of After-Cataract (AQUA; for PCO occurrence), visual acuity, anterior fibrosis, capsule-optic edge interaction and distance between anterior and posterior capsule IOL surface were analysed.

RESULTS

After a mean follow-up of 38 ± 1.95 months, Nd:YAG capsulotomy occurred at a rate of 15.4% and 46.2% in the EyeCee One and iMics1 groups, respectively (p < 0.01). Respective mean PCO scores measured by AQUA were 1.57 ± 1.63 and 2.45 ± 1.44 (p = 0.019). A distinct gap between the anterior capsule and the IOL optic was present in 89% of eyes implanted with EyeCee One and 13% of iMics1 eyes. A gap between the posterior capsule and the posterior surface of the lens was observed in 76% of EyeCee One eyes and 35% of iMics1 eyes.

CONCLUSIONS

Study findings suggest that PCO and Nd:YAG capsulotomy rates are significantly lower in eyes implanted with the EyeCee One IOL compared to the iMics1 IOL. Optic sharpness and lens material seem to be the decisive factors, while the stepped edge beneath the haptic junction appeared to be ineffective.

Comparison of posterior capsule opacification development with 2 single-piece intraocular lens types

PURPOSE

To evaluate the differences in the incidence of posterior capsule opacification (PCO) and visual and optical performance between 2 hydrophobic acrylic single-piece sharp-edged intraocular lenses (IOLs) over 3 years.

SETTING

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

DESIGN

Prospective randomized case series.

METHODS

Patients with bilateral cataract were prospectively randomized to receive an Eyecee One IOL (IOL A) or an Acrysof SN60WF IOL (IOL B) and were followed for 36 months. The corrected distance visual acuity (CDVA) and IOL decentration and tilt were measured. The PCO was quantified by analysis of standardized retroillumination images.

RESULTS

The study comprised 160 eyes of 80 patients. The PCO incidence was low for both IOLs at all follow-up visits. Three years postoperatively, the median objective PCO score was 1.4 (range 0 to 5.6) for IOL A and 1.5 (range 0 to 5.0) for IOL B (P = .67). The neodymium:YAG (Nd:YAG) capsulotomy rate 3 years after surgery was 16.4% and 6.0% (P = .06), respectively. Visual acuity and contrast sensitivity outcomes were also comparable at all follow-up visits.

CONCLUSIONS

Both IOLs showed good capsular bag performance and low PCO rates 3 years after surgery. Both IOLs also showed comparable results for visual acuity, contrast sensitivity, decentration and tilt, PCO score, slitlamp examination, and Nd:YAG capsulotomy rates.

Edge profile of commercially available square-edged intraocular lenses: Part 2

PURPOSE

To analyze the sharpness of the posterior optic edge and edge thickness of intraocular lenses (IOLs) marketed with a square-edged profile.

SETTING

University of Brighton and Brighton and Sussex University Hospitals NHS Trust, Brighton, England.

DESIGN

Laboratory study.

METHODS

Fourteen square-edged 20.0 diopter IOLs were analyzed, including 9 hydrophobic IOLs (AF-1, AF-1 iSert, Clareon, EyeCee One Crystal, CT Lucia, Envista, EyeCee One, Vivinex iSert, and RayOne Hydrophobic) and 5 hydrophilic IOLs (Asphira, CT Asphina, Incise, Synthesis, and RayOne Hydrophilic). All the IOLs were scanned following a previously published standardized technique using environmental scanning electron microscopy. The posterior optic edges were scanned at a magnification of ×500 and ×200 to measure the radius of curvature of the posterior optic edges and the optic edge thickness.

RESULTS

The radius of curvature of the posterior optic edges ranged from 4.6 to 20.6 μm. Except for the Incise IOL (7.7 μm), all hydrophilic IOLs (Synthesis [10.6 μm], Asphira [13.7 μm], RayOne Hydrophilic [14.0 μm], CT Asphina [13.7 μm]) had a radius of curvature greater than 10.0 μm. For the hydrophobic IOLs, the radius of curvature was less than 10.0 μm for the Clareon (7.9 μm), EyeCee One Crystal (4.7 μm), Vivinex iSert (7.6 μm), and CT Lucia (4.6 μm), and greater than 10.0 μm for the Envista (19.7 μm), EyeCee One (13.7 μm), AF-1 iSert (19.7 μm), AF-1 (19.7 μm) and the RayOne Hydrophobic (20.6 μm). The Vivinex iSert (150.5 μm) and the Incise (218.2 μm) were the thinnest IOLs, and the RayOne Hydrophobic (375.8 μm) and RayOne Hydrophilic IOLs (477.1 μm) were the thickest of the hydrophobic and hydrophilic IOLs, respectively.

CONCLUSIONS

Commercially marketed square-edged IOLs still differed in the sharpness of the posterior optic edge. More hydrophobic IOLs have rounder edges than those studied 10 years ago. Variations in the edge profile of hydrophobic IOLs were greater compared with the hydrophilic IOLs.

Open-capsule intraocular lens to prevent posterior capsule opacification

PURPOSE

To develop a single-piece open-capsule intraocular lens (IOL) that can be inserted through a small incision and that prevents posterior capsule opacification (PCO) by expanding the capsule and circulating aqueous humor into the capsular bag.

SETTING

Department of Ophthalmology, Dokkyo Medical University, Tochigi, Japan.

DESIGN

Experimental study.

METHOD

Using the same hydrophobic acrylic material as the NY-60 IOL, a prototype open-capsule IOL was constructed. The IOL has a single optic and 2 haptics, with a 2.8 mm high spacer and holes through which aqueous humor circulates into the capsular bag by separating the anterior capsule from the posterior capsule and expanding the capsule. The open-capsule IOL or NY-60 (as a control group) was inserted in rabbit eyes. Posterior capsule opacification development was evaluated by measuring the thickness of the cell layer at the center of the posterior capsule on histopathologic specimens and statistically comparing the thickness between the open-capsule IOL group and control group.

RESULTS

The open-capsule IOL could be inserted through a 3.2 mm corneal incision using a D cartridge. The mean thickness of the cell layer at the center of the posterior capsule was 4.78 μm ± 2.61 (SD) in the open-capsule IOL group and 101.14 ± 25.19 μm in the control group and was significantly smaller in the open-capsule IOL group.

CONCLUSION

The prototype single-piece IOL could be implanted through a small incision and prevented PCO by expanding the lens capsule and circulating aqueous humor into the capsular bag.

Outcome of various Hydrophobic Acrylic Intraocular Lens Implantations in Children with Congenital Cataract

PURPOSE

To evaluate performance of different intraocular lenses (IOLs) after cataract surgery in children aged less than 2 years with regards to rates of visual axis opacification (VAO).

METHODS

This was a retrospective chart review of children <2 years of age undergoing cataract surgery with primary posterior capsulotomy, anterior vitrectomy, and IOL over a period of 5 years with minimum follow-up of 1 year at a tertiary care institute. Children with microphthalmos, persistent fetal vasculature, traumatic cataract, aphakia, secondary IOLs, or any other coexisting ocular disease were excluded.

RESULTS

A total of 257 eyes of 159 children were included in the study. The mean age at the time of surgery was 11.63 ± 7.916 months (range 6-23 months). A total of 29 eyes of 16 children underwent phacoaspiration with implantation of SA60 AT (AcrySof, Alcon, Fort Worth, TX); 75 eyes of 45 children received Hoya IOL (Hoya-PS AF-1 Series, Model PC-60AD, Hoya, Japan), 70 eyes of 46 patients received Sensar (Abbott Medical Optics Inc., Santa Ana, CA, USA), and 83 eyes of 52 children received MA60AC (AcrySof). At mean follow-up of 18.31 ± 15.04 months, 22.46% of the patients required resurgery for visual axis obscuration. By multiple regression analysis, the rate of visual axis obscuration was affected by the rate of perioperative complications (p = 0.001) and not affected by age (p = 0.98), type of IOL (p = 0.104), or site of IOL implantation (p = 0.603).

CONCLUSION

Our findings suggest comparable rates of VAO for children less than 2 years of age receiving different types of hydrophobic acrylic IOLs.

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.

Five-year incidence of Nd:YAG laser capsulotomy and association with in vitro proliferation of lens epithelial cells from individual specimens: a case control study

Background

The aims of this study were to determine the 5-year incidence of posterior capsule opacification (PCO) requiring Nd:YAG laser capsulotomy in a representative mixed cohort of cataract patients, to determine risk factors for PCO and to investigate possible association with growth of human lens epithelial cells (HLEC) in vitro.

Methods

Pieces of the anterior lens capsule and adhering HLEC were obtained at cataract surgery and cultured individually. After one and two weeks respectively, cultured cells were stained with carboxy-fluorescein diacetate succinimidyl ester (CFDA SE), after which image processing software was used to determine the area of the confluent cell layer. The 5-year incidence of Nd:YAG laser capsulotomy in this cohort was determined through medical records and by mail or telephone interviews. For statistic analyses Mann–Whitney U-test, Fisher’s exact test and binary logistic regression were used.

Results

Data on treatment/no treatment for PCO was obtained from 270 patients with a median follow-up time of 57 months (range 50–64 months). The three-year cumulative incidence of PCO was 5.2% and the cumulative 5-year incidence was 11.9%. Patients who had undergone Nd:YAG laser capsulotomy were significantly younger (median 71 years) than patients who did not receive treatment for PCO (median 75 years, p = 0.022). Logistic regression demonstrated that apart from younger age, follow-up time and type of intraocular lens (IOL) were associated with risk of PCO, with hydrophilic 1-piece IOLs conferring a higher risk than hydrophobic acrylic 1-piece or 3-piece IOLs (adjusted OR = 9.4, 95% CI 2.5-35.7, p = 0.001). Of the 270 patients from whom information could be retrieved regarding PCO treatment, in vitro cell culture could be established and quantified from 185 patients. No significant difference in cell growth in vitro was shown between patients subsequently requiring/not requiring Nd:YAG laser capsulotomy.

Conclusions

The cumulative 5-year incidence of 11.9% is comparable or slightly higher than reported in other recent studies. The type of IOL was the most important risk factor for PCO in this study, whereas intrinsic proliferative capacity of the individual’s lens epithelial cells seems to be less important for subsequent PCO development.

Posterior capsule opacification and neodymium:YAG rates with 2 single-piece hydrophobic acrylic intraocular lenses: three-year results

PURPOSE

To compare the incidence and intensity of posterior capsule opacification (PCO) between 2 similar 1-piece foldable hydrophobic acrylic intraocular lenses (IOLs) over 3 years.

SETTING

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

DESIGN

Randomized prospective patient- and examiner-masked clinical trial with intraindividual comparison.

METHODS

Patients with bilateral age-related cataract had cataract surgery and implantation of a Tecnis ZCB00 continuous-optic-edge IOL in 1 eye and an Acrysof SA60AT interrupted-optic-edge IOL in the other eye. Postoperative examinations were performed at 6 months and 3 years. Digital retroillumination images were taken of each eye. The amount of PCO (score 0 to 10) was assessed subjectively at the slitlamp and objectively using automated image-analysis software.

RESULTS

The study comprised 54 patients (108 eyes). The mean objective PCO score was 1.3 ± 1.7 (SD) for the continuous-optic-edge IOLs and 0.9 ± 1.3 for the interrupted-optic-edge IOLs (P=.10). Three years postoperatively, a neodymium:YAG (Nd:YAG) capsulotomy was performed in 26.1% of eyes with the continuous-optic-edge IOL and 21.7% with the interrupted-optic-edge IOL (P=.56). There was no significant difference in corrected distance visual acuity, capsulorhexis–IOL overlap, capsule folds, or anterior capsule opacification 3 years after surgery.

CONCLUSIONS

Both IOLs had comparable PCO and Nd:YAG rates 3 years postoperatively. The optimized barrier function of the continuous-optic-edge IOL and the material properties of the interrupted-optic-edge IOL seemingly outbalanced the effect on lens epithelial cell migration and proliferation beneath the optic.

Posterior capsule opacification with the iMics1 NY-60 and AcrySof SN60WF 1-piece hydrophobic acrylic intraocular lenses: 3-year results of a randomized trial

PURPOSE

To compare the intensity of posterior capsule opacification (PCO) 3 years after implantation of 2 different 1-piece foldable hydrophobic acrylic intraocular lenses (IOLs).

DESIGN

Randomized, prospective, patient- and examiner-masked clinical trial with intraindividual comparison.

METHODS

One hundred patients with bilateral age-related cataract (200 eyes) had standard cataract surgery with implantation of an iMics1 NY-60 IOL (Hoya Corp) in one eye and an AcrySof SN60WF IOL (Alcon Laboratories) in the other eye. Follow-up examinations were performed at 1 week and 3 years. Digital retroillumination images were obtained of each eye. The main outcome measure was PCO score (scale, 0 to 10) assessed subjectively at the slit lamp and objectively using automated image analysis software (Automated Quantification of After-Cataract) 3 years after surgery.

RESULTS

The objective PCO score (mean ± standard deviation) was 3.0 ± 2.0 for the iMics1 NY-60 IOL and 1.9 ± 1.4 for the AcrySof SN60WF IOL (P < .001). Three years after surgery, 35.6% of patients underwent a neodymium:yttrium-aluminum-garnet capsulotomy in the iMics1 NY-60 eye and 13.7% underwent a capsulotomy in the AcrySof SN60WF eye (P = .001). There was no statistically significant difference in best-corrected visual acuity, rhexis-IOL overlap, capsular folds, or anterior capsule opacification. Glistening formations were found in no iMics1 NY-60 IOLs, but in 97% of the AcrySof SN60WF IOLs.

CONCLUSIONS

Comparison of 2 sharp-edged single-piece IOLs of similar design and hydrophobic acrylic material indicated a statistically significant difference in PCO and neodymium:yttrium-aluminum-garnet capsulotomy rate 3 years after surgery.

Posterior capsule opacification and capsular bag performance of a microincision intraocular lens

PURPOSE

To assess the axial stability and posterior capsule opacification (PCO)-inhibiting efficacy of a microincision hydrophilic intraocular lens (IOL) (Idea 613 XC) and a standard hydrophobic open-loop acrylic IOL (Acrysof SA60AT).

SETTING

Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom.

DESIGN

Clinical trial.

METHODS

Patients with bilateral cataract received a microincision cataract surgery (MICS) IOL in 1 eye and a small-incision cataract surgery (SICS) IOL in the contralateral eye. Follow-up examinations were performed immediately after surgery and postoperatively at 1 week and 3 and 24 months. Posterior capsule opacification was assessed using retroillumination photography. Anterior chamber depth (ACD) was measured using partial coherence laser interferometry, and IOL tilt and decentration were measured using a Purkinje meter.

RESULTS

Seventy eyes (35 patients) were enrolled. The mean ACD at 3 months was 4.91 mm ± 0.26 (SD) in the MICS group and 4.60 ± 0.23 mm in the SICS group. The anterior IOL shift over the first 3 months was slightly smaller with the MICS IOL (81 μm) than with the SICS IOL (254 μm). The mean ACD was 0.377 ± 178 μm deeper with the MICS IOL (P<.01, paired t test). Two years postoperatively, the amount of regeneratory PCO was higher with the MICS IOL than with the SICS IOL (image analysis software score 2.6 versus 1.9; P=.005).

CONCLUSIONS

Two years after surgery, the PCO rate was slightly higher with the MICS IOL. The 2 IOLs had similar performance in terms of axial stability, decentration, and tilt.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned. Additional disclosures are found in the footnotes.

Pathology of 219 human cadaver eyes with 1-piece or 3-piece hydrophobic acrylic intraocular lenses: capsular bag opacification and sites of square-edged barrier breach

PURPOSE

To assess capsular bag opacification and sites of initial posterior capsule opacification (PCO) in human cadaver eyes with square-edged 1-piece or 3-piece hydrophobic acrylic intraocular lenses (IOLs).

SETTING

John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, USA.

DESIGN

Experimental study.

METHODS

Eyes were immersed in 10% formalin after enucleation and had anterior segment scanning with very-high-frequency ultrasound (Artemis). After the eyes were sectioned at the equator, gross examination of the anterior segment was performed from the posterior aspect to assess capsular bag opacification, anterior capsule coverage of the IOL edge, and IOL fixation. Selected eyes had histopathologic examination.

RESULTS

One hundred nineteen eyes with 1-piece IOLs and 100 with 3-piece IOLs were included in the analyses of capsular bag opacification. There was no difference in central (P=.29) or peripheral (P=.76) PCO. In 63 of 84 eyes with a 1-piece IOL and peripheral PCO, the optic-haptic junction was the site of initiation. In eyes with a 3-piece IOL, initial peripheral PCO was observed at nearly the same rate whether there was full 360-degree anterior capsulorhexis overlap of the optic or no overlap (P=.13). In the latter, the site of PCO initiation was in areas lacking capsulorhexis coverage in 46% of eyes.

CONCLUSIONS

There was no difference in central or peripheral PCO between 1-piece and 3-piece hydrophobic acrylic IOLs. With 1-piece IOLs, PCO tended to start at the optic-haptic junctions. With 3-piece IOLs, full anterior capsule coverage did not produce a statistically significant benefit with respect to PCO prevention.

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.

Evaluating and defining the sharpness of intraocular lenses: microedge structure of commercially available square-edged hydrophilic intraocular lenses

PURPOSE

To evaluate the microstructure of the edges of currently available hydrophilic acrylic intraocular lenses (IOLs) in terms of their deviation from an "ideal" square as a follow-up of preliminary in vitro studies of experimental poly(methyl methacrylate) IOLs and commercially available foldable hydrophobic IOLs.

SETTING

Berlin Eye Research Institute, Berlin, Germany.

METHODS

Twenty-four designs of hydrophilic acrylic IOLs were used in this study. For each design, a +20.0 diopter (D) IOL and a +0.0 D IOL (or the lowest available plus dioptric power) were evaluated. The IOL edge was imaged under low-vacuum (0.7 torr), high-magnification scanning electron microscopy (SEM) using an environmental microscope and standardized technique. The photographs were imported to a digital computer program, and the area above the posterior-lateral edge, representing the deviation from a perfect square, was measured in square microns.

RESULTS

Currently available hydrophilic acrylic IOLs labeled as square edged had an area of deviation from a perfect square ranging from 60.84 to 871.51 microm(2) for the +20.0 D IOLs and from 35.52 to 826.55 microm(2) for the low-diopter IOLs. Although some differences in edge finishing between the IOLs analyzed were observed, edge surfaces of hydrophilic acrylic IOLs appeared overall smooth under environmental SEM.

CONCLUSIONS

Analysis of the microstructure of the optic edge of currently available square-edged hydrophilic acrylic IOLs showed a large variation of the deviation area from a perfect square.

Effect of intraocular lens design on posterior capsule opacification

Posterior capsule opacification (PCO) remains the most common long-term complication after cataract surgery. Many studies have attempted to identify factors that influence the development of PCO. The aim of this systematic review based on Cochrane methodology was to summarize the effects of intraocular lens (IOL) geometry, including modifications of the IOL optic (especially optic edge design) and haptics, on the development of PCO. Twenty-six prospective randomized controlled trials with a follow-up of at least 12 months were included. In 5 of 7 studies, visual acuity was better in sharp-edged IOLs than in round-edged IOL. The PCO score was significantly lower with sharp-edged IOLs but did not differ significantly between 1-piece and 3-piece open-loop IOLs. Because of the significant difference in the PCO score, sharp-edged IOL optics should be preferred to round-edged IOL optics.

Prevention of lens epithelial cell growth in vitro using mibefradil-containing PLGA micro particles

The prevention of the posterior capsule opacification is still unsolved. To interfere with proliferating cells the T-type calcium channel antagonist Mibefradil was immobilized in poly-lactic-co-glycolic-acid micro particles which were fixed at a capsular tension ring and tested in a human organ culture model as well as in human lens cells HLE-B3 in vitro. It is feasible to get a release significantly affecting cell viability and growth evaluated by MTT test and cell cycle analysis. In addition, Bionas^® sensor chips were used for time-dependent adhesion experiments in living lens cells. Interestingly, the concentration of Mibefradil which inhibited subconfluent cells is not effective in confluent cells. This is an important feature for the protection of the intact tissue in the eye.

Phacoemulsification and intraocular lens implantation in eyes with long axial length

We evaluated the results of phacoemulsification and intraocular lens implantation in 414 eyes with long axial length and classified them according to axial length (AL): Group A: AL: 25-28 mm, Group B: AL >28 mm. Intraoperative maneuvers, pre- and postoperative photocoagulation for predisposing retinal lesions and retinal detachment rates were significantly higher in Group B than Group A. Eyes with an axial length over 28 mm are prone to more problems when compared to those with an axial length between 25 and 28 mm.

Unfolding characteristics of a new hydrophobic acrylic intraocular lens, and possible association with complications in triple procedures

BACKGROUND

To evaluate the relationship between complications observed in triple procedures and the unfolding characteristics of the HOYA AF-1 lens.

METHODS

Intraoperative and postoperative complications of 242 eyes undergoing vitrectomy, phacoemulsification and intraocular lens (IOL) implantation were reviewed. Ninety eyes were implanted with the AF-1 lens (VA60BB), 100 eyes with a polymethylmethacrylate lens (824C) and 52 eyes with an AcrySof lens (SA60AT). The unfolding characteristics of the VA60BB and SA60AT were also experimentally examined.

RESULTS

Intraoperative iatrogenic posterior capsular holes caused by the vitreous cutter were observed in two eyes with the VA60BB, in three eyes with the 824C, and in one eye with the SA60AT. Significant rotation of the curled IOL in the capsular bag during implantation, with dislocation of the IOL into the vitreous cavity through the hole occurred in the two eyes with the VA60BB. Postoperatively, posterior synechia of the iris occurred more frequently in the VA60BB group (seven eyes) than in the 824C group (one eye) or the SA60AT group (one eye). In the experimental study, the unfolding time of the VA60BB lens was longer than that of the SA60AT lens. The overall diameter of the VA60BB lens after unfolding remained shorter than that before folding.

CONCLUSION

Incomplete unfolding of the VA60BB appears to cause intraoperative rotation of the IOL in the capsular bag, resulting in IOL dislocation into the vitreous cavity in the presence of a posterior capsular hole. This lens also appears to be associated with higher rate of postoperative complications in triple procedures.

The Relationship between the Adhesion Characteristics of Acrylic Intraocular Lens Materials and Posterior Capsule Opacification

PURPOSE

To investigate the relationship between the adhesion characteristics of similarly designed hydrophobic acrylic intraocular lenses (IOLs) and posterior capsule opacification (PCO).

METHODS

Three similarly shaped hydrophobic acrylic IOLs with a sharp-edged optic were used. Adhesive force of IOLs was measured with a tackiness tester. Human lens epithelial cells (LECs) were grown on each IOL for 48 h. LECs were then stained with crystal violet, which served as an index of the amount of cells attached to IOLs. Cellular migration and proliferation assays were performed using chamber inserts containing a collagen membrane. After 96 h of incubation, the collagen membranes were stained with hematoxylin and eosin for analysis. Three similarly shaped IOLs were implanted in rabbits. The eyes were enucleated 3 weeks later and analyzed for PCO area.

RESULTS

Hydrophobic acrylic IOLs were classified into three groups: A (less adhesive), B (moderately) and C (highly). The migration area of LECs on the collagen membrane was 5.65 +/- 4.5% in group A, 2.83 +/- 2.1% in group B, and 1.41 +/- 1.5% in group C, with a significant difference between groups A and C (p < 0.05). The mean percentage area of PCO in the rabbit eye was 19.4 +/- 16.7% in group A, 17.5 +/- 8.5% in group B, and 5.5 +/- 3.8% in group C, with a significant difference between groups A and C (p < 0.05).

CONCLUSION

Adhesive force of hydrophobic acrylic IOLs may play an important role in preventing PCO. Among the similarly shaped hydrophobic acrylic IOLs, IOLs of highly adhesive material inhibited LEC migration and PCO more than IOLs of less adhesive material.

Influence on posterior capsule opacification and visual function of intraocular lens optic material

PURPOSE

To examine the influence of optic material on posterior capsule opacification (PCO) by comparing PCO and visual functions between eyes with an acrylic intraocular lens (IOLs) and those with a silicone IOL of the same optic design and with the same haptics.

DESIGN

Randomized clinical trial.

METHODS

One hundred patients scheduled for phacoemulsification surgery underwent implantation of an acrylic IOL (AMO Sensar; AR40e) in one eye and implantation of a silicone IOL (ClariFlex) of the same optic design and loops in the fellow eye. Eighty-nine patients (89%) remained for analysis. The PCO value was measured using the Scheimpflug videophotography system at one, three, six, 12, 18, 24, 30, and 36 months postoperatively. The incidence of eyes that required a neodymium:yttrium-aluminum-garnet (Nd:YAG) laser capsulotomy was examined; visual acuity and contrast sensitivity with and without a glare source were also evaluated.

RESULTS

The mean PCO value did not increase significantly during follow-up in either the acrylic or silicone IOL group. When comparing the groups, no statistically significant difference was found in the PCO or in the incidence of Nd:YAG capsulotomy, although both tended to be slightly better in the silicone group than in the acrylic group. There was also no significant difference between the groups in visual acuity or in photopic and mesopic contrast sensitivity with or without glare.

CONCLUSIONS

When acrylic and silicone IOLs are of the same optic design and with the same haptics, the optic material does not influence the development of PCO enough to impair visual function.

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.

[Current cataract surgery for uveitis in childhood]

Cataract formation is a frequent complication in childhood uveitis. The management of cataracts in childhood uveitis may be particularly difficult. Patient selection is important for successful surgery. Preoperative evaluation is required in order to specify the course and etiology of uveitis. Complete quiescence of the inflammation in required before surgery. The surgical trauma should be minimized. Intraocular lens implantation may be proposed for selected uveitis children and may be considered in well controlled juvenile idiopathic arthritis associated uveitis, e.g. with the use of immunosuppressive drugs or TNF-alpha inhibitors. Postoperatively, the anti-inflammatory medication must be increased and continued for 8-10 weeks.

Contact inhibition of migrating lens epithelial cells at the capsular bend created by a sharp-edged intraocular lens after cataract surgery

PURPOSE

To investigate whether the lens epithelial cells (LECs) at the capsular bend created by a sharp-edged intraocular lens (IOL) are in the G(0) phase of the cell cycle.

SETTING

Nishi Eye Hospital, Osaka, Japan.

METHOD

A CeeOn Edge silicone IOL (AMO) with sharp edges was implanted in 1 eye and a PhacoFlex II silicone IOL (AMO) with rounded edges in the contralateral eye after standard cataract surgery in 6 rabbits. Immunohistochemical staining for the Ki-67 antibody was performed 1 day, 3, 4, and 7 weeks after surgery.

RESULTS

In eyes with the sharp-edged IOL, LECs with thin, elongated nuclei accumulated at, but did not extend beyond, the capsular bend and stained negative for the Ki-67 antibody, indicating that they were in the G(0) phase of the cell cycle. In contrast, in the eye with the round-edged IOL, continuous migration of a predominantly monolayer of LECs over the IOL and onto the posterior capsule occurred. These cells were Ki-67 positive, indicating that they were proliferating.

CONCLUSIONS

Lens epithelial cells at the capsular bend of sharp-edged IOLs were in the G(0) phase of the cell cycle, indicating that they were contact inhibited. These findings support the theory the sharp posterior optic edge of the IOL inhibits LEC migration, reducing formation of posterior capsule opacification. Whether these LECs can reactivate when the capsular bend is eliminated by later formation of a Soemmerring's ring requires further studies.

Capsulorhexis contraction after cataract surgery: Comparison of sharp anterior edge and modified anterior edge acrylic intraocular lenses

PURPOSE

To evaluate the reduction in the anterior capsule opening after phacoemulsification, continuous curvilinear capsulorhexis, and implantation of 1 of 2 acrylic intraocular lenses (IOLs).

SETTING

Department of Ophthalmology, Vejle Hospital, Vejle, Denmark.

METHODS

Eighty-four patients (84 eyes) were included in a prospective randomized study. All had phacoemulsification followed by implantation of an IOL with a modified anterior edge (38 eyes) or a sharp anterior edge (46 eyes). One day (baseline) and 3 months postoperatively, the area of the anterior capsule opening was measured using retroillumination photographs.

RESULTS

There was a significant reduction in the area of the anterior capsule opening from 1 day to 3 months postoperatively in both groups (P<.001). There was no significant difference in the reduction in the anterior capsule opening between the modified-edge IOL and the sharp-edged IOL (P = .313). The shrinkage was independent of the area of the anterior capsule opening at baseline.

CONCLUSIONS

There was a reduction in the area of the anterior capsule opening in all patients. The design of the anterior edge of the 2 IOLs did not influence the degree of anterior capsule opening shrinkage. The shrinkage was independent of the size of the area 1 day postoperatively.

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.

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.

Effect of ophthalmic Nd:YAG laser energy on intraocular lenses after posterior capsulotomy in normal dog eyes

OBJECTIVE

To determine Nd:YAG laser energy requirements for posterior capsulotomy and intraocular lens (IOL) damage threshold for foldable acrylic IOLs as compared to traditional polymethylmethacrylate (PMMA). MATERIALS AND PROCEDURES: Four groups of five-six fresh canine cadaver eyes were used in this study. The groups included (1) unaltered eyes (2) aphakic eyes (3) eyes implanted with PMMA IOLs, and (4) eyes implanted with acrylic IOLs. Laser energy was delivered to the posterior capsule in grid fashion for 10 sites each of five levels of laser energy ranging from 0.5 mJ to 9 mJ. Number of successful capsulotomy sites was recorded based on slit-lamp observation. Sites of IOL damage were evaluated using scanning electron microscopy (SEM). Statistical analysis of number of capsulotomies and IOL defects per laser energy level was conducted among and between groups using anova with Tukey's HSD test.

RESULTS

When comparing groups (a) including all energy levels (n = 25) and (b) by specific energy levels (n = 5), there was no significant difference (P < 0.05) in number of successful capsulotomy sites between IOL types. The 50% incidence threshold for successful capsulotomy was 2.74 mJ for acrylic IOLs and 2.64 mJ for PMMA IOLs. Energy-dependent damage to both types of IOL was detected for medium, high-medium, and high laser energy. Calculated 50% damage threshold was 4.9 mJ for acrylic IOL and 5.7 mJ for PMMA IOL. Damage to the IOL varied subjectively between IOL type, but there was no significant difference in number of defects caused, with the exception of high-medium energy.

CONCLUSIONS

Both posterior lens capsules and IOLs were disrupted in an energy-dependent manner with minimal difference in number of capsulotomy sites or damage to the IOL between acrylic and PMMA IOLs. A therapeutic margin between capsulotomy threshold (2.6-2.7 mJ) and IOL damage threshold (4.9-5.7 mJ) was determined to reliably achieve capsulotomies with minimal IOL damage for both acrylic and PMMA IOLs in normal canine cadaver eyes.

Influences of optic edge design on posterior capsule opacification and anterior capsule contraction

PURPOSE

To investigate the influence of optic edge design on posterior capsule opacification (PCO) and anterior capsule contraction (ACC).

METHODS

A total of 43 eyes of 43 patients scheduled to undergo cataract surgery were included in this study. Patients received either a Sensor AR40 intraocular lens (IOL) or a Sensor AR40e IOL. The area of the anterior capsule opening (ACO) was determined by diaphanoscopy using the anterior eye segment analysis system EAS-1000 at 1 day, 1 week and 1, 3, 6 and 12 months postoperatively. Posterior capsule opacification was evaluated objectively in two ways, using either the EAS-1000 or POCOman.

RESULTS

There was no significant difference between the two groups in either ACO area or percentage reduction of ACO area at any time-point after surgery. The difference in the degree of PCO 1 year after surgery was not significant when measured by either the EAS-1000 or POCOman.

CONCLUSIONS

A sharp IOL edge is required to prevent PCO. Sharp-edged IOLs do not appear to be a risk factor for ACC.

Effect of anterior capsule polishing on the posterior capsule opacification–inhibiting properties of a sharp-edged, 3-piece, silicone intraocular lens

PURPOSE

To evaluate the long-term effects of anterior capsule polishing on regeneratory posterior capsule opacification (PCO), anterior capsule opacification (ACO), and fibrotic PCO with a silicone intraocular lens (IOL) with sharp optic edges.

SETTING

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

METHODS

This prospective bilateral randomized patient- and examiner-masked clinical trial comprised 130 eyes of 65 patients with bilateral age-related cataract. All eyes had implantation of a 3-piece silicone IOL with a truncated, sharp-edged optic (CeeOn Edge 911A, Advanced Medical Optics). In 1 eye, the anterior capsule was extensively polished using an aspiration curette after phacoemulsification and cortex aspiration. Regenerative PCO was quantified objectively, while ACO and fibrotic PCO were graded subjectively 1, 2, 3, and 5 years postoperatively.

RESULTS

The mean ACO score was significantly lower in the eyes in which the anterior capsule had been polished (1 year, P<.02; 2 years, P<.03; 3 years, P<.01; 5 years, P<.01). The mean difference in regeneratory PCO and fibrotic PCO scores between the 2 groups was not statistically significant.

CONCLUSIONS

Three years after cataract surgery, eyes in which the anterior capsule had been polished had significantly less ACO. However, polishing did not lower PCO intensity when a sharp-edged CeeOn 911A IOL was implanted in the bag. Although results indicate that anterior capsule polishing may enhance the development of regeneratory PCO, this trend did not reach statistical significance.

Analysis of intraocular lens surface properties with atomic force microscopy

PURPOSE

To analyze the surface optics of 4 currently available intraocular lenses (IOLs) with atomic force microscopy.

SETTING

Licryl Laboratory, University of Calabria, Rende, Italy.

METHODS

The surface roughness and topography of poly(methyl methacrylate) (PMMA), silicone, hydrophobic, and hydrophilic acrylic IOLs were evaluated with atomic force microscopy in contact mode. The analysis was performed in a liquid environment using cantilevers with a 0.01 Newtonw/meter nominal elastic constant. Measurements were made over areas of 10 microm2 on different locations of the posterior optic surface of the IOL.

RESULTS

Atomic force microscopy permitted high-resolution imaging of IOL optic surface characteristics. Surface topography showed different features with respect to the lens biomaterial. The root-mean-square roughness of the IOL optic surface was significantly different between lenses of various materials (P < .001). The hydrophobic acrylic and silicone IOLs had the lowest mean surface roughness, 3.8 nm +/- 0.2 (SD) and 4.0 +/- 0.5 nm, respectively, and the 2 PMMA IOLs had the highest mean surface roughness, 6.6 +/- 0.3 nm and 7.0 +/- 0.6 nm.

CONCLUSIONS

Atomic force microscopy was effective and accurate in analyzing IOL optics. The surface topography of IOLs may vary with different manufacturing processes.

Effect of cortical cleaving hydrodissection on posterior capsule opacification in age-related nuclear cataract

PURPOSE

To evaluate the effect of multiquadrant cortical cleaving hydrodissection on the development of posterior capsule opacification (PCO) after phacoemulsification.

SETTING

Iladevi Cataract and IOL Research Center, Ahmedabad, India.

METHODS

A prospective randomized triple blind clinical trial was conducted in 86 eyes (86 patients) having phacoemulsification. Eyes were assigned randomly to Group 1, multiquadrant cortical cleaving hydrodissection and hydrodelineation (n = 48 eyes), or Group 2, no multiquadrant cortical cleaving hydrodissection, only hydrodelineation (n = 38 eyes). Age-related nuclear sclerosis (grading system of 1 to 5) and age greater than 50 years were included. Diabetes mellitus and associated eye diseases were excluded. Standard phacoemulsification with implantation of an AcrySof MA30BA intraocular lens (IOL) was done in both groups. High-resolution digital retroillumination images of the posterior capsule were analyzed at 4 years using POCOman software. Seven patients dropped out (8.1%). Outcome measures were incidence and percentage area of PCO. Test of proportions, independent sample t test, and 95% confidence intervals (CIs) were noted.

RESULTS

In Groups 1 and 2, the mean age was 58 years +/- 4 (SD) and 57 +/- 5 years, respectively (P = .702; 95% CI, 1.90-2.81); mean follow-up was 48.4 +/- 2.5 months and 49.3 +/- 1.9 months, respectively (P = .687; 95% CI, 1.186-0.7856); incidence of PCO was 11 of 44 (25%) and 12 of 35 (34.3%), respectively (P = .317; 95% CI, 0.359-0.0889); percentage area of PCO was 14.3% and 25.6%, respectively (P = .006; 95% CI, -19.19 to -3.44). One of 44 eyes (2.27%) and 2 of 35 eyes (5.7%) in the groups, respectively, had a neodymium:YAG capsulotomy.

CONCLUSION

Although no difference was noted in the incidence of PCO, in eyes that had PCO, the percentage of the area of the central posterior capsule involved by PCO was significantly lower in eyes that had multiquadrant cortical cleaving hydrodissection than in those that did not.

Comparison of posterior capsule opacification between fellow eyes with two types of acrylic intraocular lens

PURPOSE

To compare the degree of posterior capsule opacification (PCO) and visual function between fellow eyes that received two different types of hydrophobic acrylic intraocular lenses (IOLs).

METHODS

Forty-five patients underwent bilateral phacoemulsification and implantation of an Alcon AcrySof IOL (MA60AC) in one eye and an AMO Sensar IOL (AR40e) in the fellow eye. The PCO density value was measured using the Scheimpflug videophotography system at 1, 6, 12, and 24 months after surgery. The incidence of eyes that required a neodymium:YAG (Nd:YAG) laser capsulotomy, visual acuity, and contrast sensitivity with and without a glare source were also examined.

RESULTS

The mean PCO value did not show a significant increase in either the AcrySof MA60AC or Sensar AR40e IOL groups, and was similar between the two groups throughout the 24-month follow-up period. The incidence of Nd:YAG laser capsulotomy was also the same between the groups. No significant difference was found in mean visual acuity between the two IOL groups during the follow-up, and there was no significant difference in photopic or mesopic contrast visual acuity with and without a glare source at 1 and 24 months after surgery.

CONCLUSION

The degree of PCO in eyes with an AcrySof IOL are almost the same as that in eyes with a Sensar IOL, with the results that visual acuity and contrast sensitivity with and without glare are similar.

Prospective, non-randomised, long term clinical evaluation of a foldable hydrophilic single piece intraocular lens: results of the Centerflex FDA study

BACKGROUND

Owing to the improvement of modern intraocular lenses (IOLs) in terms of design and material, posterior capsule opacification (PCO) usually takes 2-3 years to develop. Thus, long term clinical evaluation of new implants is important.

METHODS

As part of a prospective, non-randomised FDA trial, the Rayner Centerflex, a foldable hydrophilic acrylic, single piece IOL was implanted in one eye of 83 patients (mean age 73.5 (SD 7.0) years). Over 3 years postoperatively, a standardised FDA protocol concerning IOL safety and efficacy was followed including evaluation of spherical equivalent (SE), best corrected distance visual acuity (BCDVA), endothelial cell count (ECC), flare meter values, PCO development, and anterior capsule shrinkage.

RESULTS

Postoperatively, mean SE was stable ranging between -0.3D and 0.17D. After 1-2 months, all patients achieved a BCDVA of 20/40 or better. At 3-6 months postoperatively, mean ECC decreased from 2612 (SD 346) cells/mm2 to 2380 (316) cells/mm2. Mean PCO score for the entire optic increased from 0.20 (0.20) months (3-6 months postoperatively) to 0.87 (0.57) resulting in a Nd:YAG rate of 29.41% after 3 years. No anterior capsule shrinkage was found.

CONCLUSION

The Centerflex showed excellent functional results, low values for endothelial cell loss and inflammatory signs, and no anterior capsule shrinkage. PCO formation was higher compared to other IOLs, which could be explained by the incomplete sharp edge at the optic-haptic junctions representing an "Achilles' heel" for cell ingrowth.

Posterior capsule opacification in myopic eyes

PURPOSE

To determine whether posterior capsule opacification (PCO) is extensive in eyes with myopia or long axial length when an intraocular lens (IOL) of low-power, zero-power, or minus-power, is implanted.

SETTING

Hayashi Eye Hospital, Fukuoka, Japan.

METHODS

Ninety eyes of 90 patients scheduled for phacoemulsification surgery were recruited. These consisted of 30 eyes with high (> or =-8 diopters [D]) myopia, 30 eyes with moderate (<-8 D and > or =-3 D) myopia, and 30 eyes with low (<-3 D) myopia. All eyes had implantation of an acrylic IOL-low-power, zero-power, or minus-power-with a sharp optic edge (AcrySof MA60BM or MA60MA, Alcon Surgical). The PCO in these eyes was measured using a Scheimpflug videophotography system (EAS-1000, Nidek) 1, 3, 6, 12, 18, and 24 months after surgery. Visual acuity and the incidence of neodymium:YAG (Nd:YAG) laser posterior capsulotomy were also examined.

RESULTS

No significant difference was observed in the mean PCO value or in the Nd:YAG capsulotomy rate between the high myopia, moderate myopia, or low myopia groups throughout the follow-up period. There was also no significant correlation between PCO value and the actual spherical power or axial length of the eye. Furthermore, although mean visual acuity tended to be worse in proportion to the degree of myopia, the difference was not statistically significant.

CONCLUSION

When an acrylic IOL of low-power, zero-power, or minus-power with a sharp optic edge was implanted, high myopia and long axial length were not associated with the degree of PCO.