Posterior capsule opacification and Nd:YAG capsulotomy rates after implantation of silicone, hydrogel and soft acrylic intraocular lenses: a two-year follow-up study

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.

Long-term effectiveness and safety of a three-piece acrylic hydrophobic intraocular lens modified with hydroxyethyl-methacrylate: an open-label, 3-year follow-up study

Background

Clareon^® is a new hydrophobic acrylic optic biomaterial designed for enhanced clarity and greater resistance to glistening. The present study evaluated the effectiveness and safety of a three-piece hydrophobic, monofocal intraocular lens (IOL) Model MA60NM, made of this new optic material.

Methods

In this prospective, multicenter, open-label study, eligible patients aged ≥60 years, underwent a unilateral implantation with IOL Model MA60NM following phacoemulsification. Patients were followed-up for up to 3 years after implantation. Visual outcome and serious adverse events (SAEs, cumulative and persistent) were compared to ISO grid rates (BS EN ISO 11979-7:2006). The primary effectiveness variable was Best Spectacle-Corrected Visual Acuity (BSCVA) at 1-year postoperative follow-up. In addition, posterior capsular opacification (PCO) was assessed qualitatively and graded by slit lamp exam on a 5-point scale at all visits.

Results

Overall, 179 and 138 patients completed the 1-year and 3-year postoperative follow-up, respectively. The BSCVA outcomes were better with IOL Model MA60NM than the ISO grid rates with 95.5% of patients at 1 year and 94.2% of patients at 3 years having achieved a BSCVA of 20/40 or better vs 92.5% in ISO grid. The incidence of cumulative or persistent SAEs was lower after Model MA60NM implantation than the ISO grid reference. The incidence of clinically significant PCO was 1.1% at the 1-year and 2.2% at the 3-year visit. Posterior capsulotomy rate was 1.1% at 1 year and 1.4% at 3 years.

Conclusion

The three-piece hydrophobic, monofocal IOL Model MA60NM was effective for the visual correction of aphakia and successfully met all the safety parameters as defined by the ISO criteria. PCO and posterior capsulotomy rates were low over the 3-year follow-up period. This study provides evidence and supports the long-term safety and effectiveness of the new optic biomaterial Clareon^®.

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.

The Effects of Three-Piece or Single-Piece Acrylic Intraocular Lens Implantation on Posterior Capsule Opacification

Purpose

To evaluate the development of posterior capsule opacification (PCO) in patients implanted with 5.5 mm optics, single-piece or three-piece acrylic intraocular lens (IOL) in cataract surgery prospectively.

Methods

This study was carried out on 267 eyes of 249 patients implanted with three-piece, 5.5 mm optics, acrylic IOL and 252 eyes of 244 patients implanted with single-piece, 5.5 mm optics, acrylic IOL by phacoemulsification technique between September 2001 and February 2003. A total of 519 eyes of 493 patients were prospectively evaluated for PCO development during the 25-month period. All the patients were analyzed periodically with anterior segment retroillumination photography. The data provided were analyzed with chi-square method.

Results

The results between the two groups for PCO development were not statistically significant. However, there was a prominent opacification of the posterior capsule where the optic and haptic junction of IOL was positioned in some patients implanted with single-piece IOL. During the follow-up period, no patients implanted with either three-piece or single-piece acrylic IOL required Nd:YAG laser capsulotomy.

Conclusions

Biocompatibility and reduced rate of PCO development are among the leading features of new generation IOLs. The intracapsular implantation of 5.5 mm optics acrylic IOLs resulted in decreased incidence of PCO and therefore greater patient satisfaction. Further studies investigating the effects of IOL optics, haptic structure and length, capsulorrhexis size, and IOL material and design features on PCO development will clarify the subject.

Long-term results of trypan blue dye irrigation in the capsular bag to prevent posterior capsule opacification: A randomized trial

Purpose:

To study the effect of capsular bag irrigation of trypan blue dye (0.06%) on posterior capsular opacification (PCO) in eyes undergoing phacoemulsification.

Methods:

This was a randomized, trial conducted at a tertiary eye care center in central India. The study included 50 patients (100 eyes) with senile cataracts who were scheduled for phacoemulsification and intraocular lens (IOL) implantation and were willing to undergo bilateral cataract surgery. One eye of each patient was randomized to one of two groups. The dye group received 0.2 ml of trypan blue injected in the capsular bag after cortical cleanup under air. The control group (other eye of the same patient) received 0.2 ml of balanced salt solution injected in a similar manner. PCO in the central 3 mm area of IOL optic was analyzed by a masked observer using an evaluation of PCO software computer analysis system at 6, 12, 24, and 36 months.

Results:

The average age of patients was 62.05 ± 6.22 in the dye group and 64.92 ± 7.16 years in the control group. The mean PCO score at 6 months was significantly lower in the dye group (0.10 ± 0.15) than in the control group (0.22 ± 0.30). There were no significant differences in the PCO scores between the two groups from 12 to 36 months. At the end of 3 years, eight eyes in the dye group and seven in the control group required YAG capsulotomy (P = 0.21).

Conclusion:

Capsular bag irrigation of trypan blue dye decreased the PCO score at 6 months, but it had no effect at 36 months.

Comparison of hydrophobic and hydrophilic intraocular lens in preventing posterior capsule opacification after cataract surgery: An updated meta-analysis

BACKGROUND

Posterior capsular opacification (PCO) is a common long-term complication of cataract surgery. Intraocular lens design and material have been implicated in influencing the development of PCO. This study evaluated the association of hydrophobic and hydrophilic intraocular lenses on preventing PCO.

METHODS

Medline, Cochrane, EMBASE, and Google Scholar databases were searched until August 3, 2016, using the following search terms: cataract, posterior capsule opacification, and intraocular lens. Eligible studies included randomized controlled trials (RCTs), retrospective, and cohort studies.

RESULTS

Eleven studies were included in the study with a total of 889 eyes/patients. The overall analysis revealed that hydrophobic intraocular lenses were associated with lower Nd:YAG laser capsulotomy rates than hydrophilic lenses [odds ratio (OR) = 0.38, 95% confidence interval (95% CI) = 0.16-0.91, P = .029]. Hydrophobic intraocular lenses were also associated with lower subjective PCO score (diff. in means: -1.32, 95% CI = -2.39 to -0.25, P = .015) and estimated PCO score (diff. in means: -2.23; 95% CI, -3.80 to -0.68, P = .005) as compared with hydrophilic lenses. Objective PCO score was similar between lens types. (diff. in means: -0.075; 95% CI, -0.18 to 0.035; P = .182). Pooled analysis found that visual acuity was similar between hydrophobic and hydrophilic intraocular lenses (diff. in means: -0.016; 95% CI, -0.041 to 0.009, P = .208).

CONCLUSION

In general, PCO scores and the rate of Nd:YAG laser capsulotomy were influenced by intraocular lens biomaterial. Lens made of hydrophobic biomaterial were overall superior in lowering the PCO score and the Nd:YAG laser capsulotomy rate, but not visual acuity.

Posterior capsular opacification and Nd:YAG capsulotomy rates with the iMics Y-60H and Micro AY intra-ocular lenses: 3-year results of a randomized clinical trial

PURPOSE

To compare the incidence and intensity of posterior capsular opacification (PCO) and neodymium:yttrium-aluminium-garnet (Nd:YAG) capsulotomy rates between two microincision intra-ocular lenses (IOLs) 3 years after surgery.

METHODS

Sixty-five patients randomly received a Y-60H IOL (HOYA Surgical Optics, Singapore) in one eye and a Micro AY IOL (PhysIOL, Liège, Belgium) in the contralateral eye during same-day bilateral cataract surgery. Eyes were examined 1 week, 20 months and 3 years after surgery. The amount of PCO (score: 0-10) was assessed subjectively at the slit lamp and objectively using automated image analysis software (aqua). Additionally, the Nd:YAG capsulotomy rate was noted.

RESULTS

Three years postoperatively, the objective PCO score of Y-60H IOLs was 1.9 ± 1.7 compared to PCO score of 1.7 ± 2.2 for the Micro AY IOLs (p = 0.66). Thirty-four percentage of the Y-60H eyes had undergone Nd:YAG capsulotomy, compared to 49% of the Micro AY eyes (p = 0.04). Significantly, more capsular folds were observed in the Y-60H IOL group (p = 0.001). There was no significant difference in best-corrected visual acuity, rhexis/IOL overlap and anterior capsule opacification 3 years after surgery.

CONCLUSION

Both microincision IOLs showed high YAG rates and comparable PCO scores 3 years after surgery. In the light of this unsatisfying PCO performance, the advantage of the present microincision IOLs over conventional IOLs must be questioned.

Effect of hydrophobic acrylic versus hydrophilic acrylic intraocular lens on posterior capsule opacification: meta-analysis

PURPOSE

This meta-analysis aims to evaluate the differences in performance of posterior capsular opacification (PCO) between hydrophobic acrylic intraocular lens (IOLs) and hydrophilic acrylic IOLs.

SETTING

Tianjin Medical University, Tianjin Eye Hospital, Tianjin Key Laboratory of Ophthalmology and Visual Science, Tianjin, China.

DESIGN

Systematic review of randomized controlled trials (RCTs) or meta-analysis.

METHODS

An electronic literature search was performed using the PubMed, EMBASE and Cochrane Library database before May in 2013 to identify prospective RCTs comparing hydrophobic acrylic IOLs and hydrophilic acrylic IOLs in patients after phacoemulsification with IOL implantation with a follow-up time of at least 1 year. Pertinent studies were selected by meeting predefined criteria and reviewed systematically by meta-analysis. The PCO scores and YAG capsulotomy rate, as indicator of PCO, were measured and discussed in a meta-analysis. Standardized mean differences (SMD), relative risk ratio (RR), and the pooled estimates were computed according to a random effect model or fixed effect model.

RESULTS

Nine prospective RCTs involving 861 eyes were included in the current meta-analysis. The hydrophobic acrylic IOLs were favored and the pooled SMD of PCO severity was 1.72 (95% confidence interval (CI), 0.20 to 1.23, P = 0.0002) and 1.79 (95% CI, 0.95 to 2.64, P<0.0001) with 1-year follow-up and 2-year follow-up respectively. The pooled RR of Nd:YAG laser capsulotomy rates at postoperative 2-year follow-up was 6.96 (95% CI, 3.69 to 13.11, P<0.00001) comparing hydrophilic acrylic IOLs with hydrophobic acrylic IOLs.

CONCLUSIONS

Compared with hydrophilic acrylic IOLs, the hydrophobic acrylic IOLs showed superior reduction in rates of PCO and laser capsulotomy in 2-year follow-up. More RCTs with standard methods for longer follow-up are needed to validate the association.

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.

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

PURPOSE

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

SETTING

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

METHODS

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

RESULTS

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

CONCLUSION

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

Optical coherence tomography of intraocular lens implants and their relationship to the posterior capsule: a pilot study comparing a hydrophobic acrylic to a plate-haptic silicone type

BACKGROUND

Optical coherence tomography (OCT) has been used to examine the anterior as well as the posterior segment and can be used to examine the intraocular lens (IOL) and their relationship to the posterior capsule in vivo.

OBJECTIVES

To use OCT to examine two of the IOLs and some of the features related to the development of posterior capsular opacification (PCO).

METHODS

This is a pilot study of a prospective (n = 12) and a retrospective (n = 14) series of patients who had uneventful phacoemulsification and IOL implantation of either hydrophobic acrylic (Acrysof; Alcon) or plate-haptic (PH) silicone (C11UB; Chiron, Bausch & Lomb) IOLs. The outcome of interest was the ability of OCT to clearly delineate the outline of the IOL optics and their appositional relationship to the posterior capsule.

RESULTS

OCT showed that hydrophobic acrylic IOLs had a better defined outline than PH silicone IOLs. It also showed close apposition between hydrophobic acrylic optics and the mid-peripheral part of the posterior capsule and the absence thereof with PH silicone IOLs.

CONCLUSIONS

Hydrophobic acrylic implants have better definition on the OCT scans than PH silicone and they develop close apposition to the posterior capsule. The latter feature is consistent with the 'no space, no cell, no PCO' concept and what is known about the effect of the implant material and design on the rate of PCO.

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.

Spring constants of capsular tension rings

PURPOSE

To determine the spring constants of several types of capsular tension rings (CTRs).

SETTING

Department of Ophthalmology, Johannes Gutenberg-University, Mainz, Germany.

METHODS

Fourteen models of CTRs provided by 9 companies were tested; all were 11.0 mm in diameter. The CTRs were positioned in a special retainer of a material-testing machine and compressed at a constant speed of 10.0 mm per minute. The distance and force values were recorded, and each CTR model was tested 3 times using a new specimen each time. The resulting measurements were used to calculate a mean spring constant for each CTR model.

RESULTS

All tested CTRs showed linear proportionality between force and compression distance. Test results were repeatable and precise. Capsular tension rings of the same model had comparable mechanical properties, and different models had different mean spring constants ranging from 0.8162 to 4.5501 mN/mm.

CONCLUSIONS

The spring constant of a CTR is a suitable mechanical characteristic to facilitate the choice of CTR model. A CTR with a low spring constant may be advantageous for the management of zonular dialysis, whereas a CTR with a higher spring constant may reduce capsular bag shrinkage more effectively.

The effect of capsulorhexis size on development of posterior capsule opacification: small (4.5 to 5.0 mm) versus large (6.0 to 7.0 mm)

PURPOSE

The most common surgically related cause of reduced vision after extracapsular cataract extraction is posterior capsule opacification (PCO), which occurs in up to 50% of eyes following cataract extraction. This study examined whether small capsulorhexes of 4.5 to 5.0 mm, which lie completely on the 5.5 mm intraocular lens (IOL), and large capsulorhexes of 6.0 to 7.0 mm, which lie completely off the lens optic, are effective in preventing PCO development.

METHODS

In this prospective study, 496 eyes of 367 patients underwent standardized phacoemulsification with capsulorhexis and capsular bag foldable acrylic IOL implantation. The patients were randomly assigned to receive either a small capsulorhexis of 4.5 to 5 mm to lie completely on the IOL optic or a large capsulorhexis of 6 to 7 mm to lie completely off the lens optic. Retroillumination photographs were taken at 6 months and then yearly.

RESULTS

Throughout the follow-up, there was less PCO in the small capsulorhexis group than in the large capsulorhexis group. CONCLUSIONS.:Small capsulorhexes were associated with less wrinkling of the posterior capsule and less PCO than were large capsulorhexes. PCO after IOL implantation has a multifactored pathogenesis. Small (4.5 to 5.0 mm) capsulorhexis and capsular bag implantation of 5.5 mm acrylic IOL are likely to reduce the PCO incidence when compared with the 6.0 to 7.0 mm capsulorhexis. The significance of the IOL optic diameter in association with the capsulorhexis size should also be documented by further studies.