Three-year follow-up of posterior capsule opacification with two different silicone intraocular lenses

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.

A survey of ocular diseases in an isolated rural Haitian community: a retrospective evaluation

PURPOSE

To report the prevalence and incidence of ophthalmic pathology from a small, rural town in Haiti and to determine the leading causes of blindness in this population.

DESIGN

Retrospective study from 2002 to 2009. Data collected include visual acuity, intraocular pressure, and ocular and family history.

METHOD

The study was conducted in a single center--Hospital de Lascahobas, Lascahobas, Haiti. Patients were natives of Lascahobas and the surrounding areas. Treatments were dispensed as indicated or warranted.

RESULTS

A total of 3702 patients were seen and examined: 51.52% were male and 49.48% were female. Ages ranged from 6 months to 92 years (mean, 48.69 SD +/- 49.94). Uncorrected refractive error was the most common diagnosis (53.27%), followed by presbyopia (43.76%), hyperopia (34.03%), and myopia (22.21%). A total 981 patients (26.50%) were diagnosed with cataract. Three hundred twenty-three (32.93%) cataract surgeries were performed. The overall postoperative complications rate was 9.29%. A total of 706 patients (19.07%) were diagnosed with glaucoma: 23.65% were glaucoma suspect and 76.35% were diagnosed with open-angle glaucoma (POAG). Of those diagnosed with POAG, 35.06% had end-stage (absolute) glaucoma. The mean age at diagnosis was 52.56 SD +/- 8.2 years. The mean intraocular pressure was 24.07 and 25.60 mm Hg, and the mean cup to disc ratio of the right eye (OD) and the left eye (OS), respectively, was 0.67 and 0.72.

CONCLUSIONS

Glaucoma was the most common cause for blindness. The most common cause of correctable vision loss was uncorrected refractive error followed by cataract. Providing constant eye care in this region will most likely decrease the incidence of correctable and permanent vision loss.

Which procedure has more effect on macular thickness: primary posterior continuous capsulorhexis (PPCC) combined with phacoemulsification or Nd:YAG laser capsulotomy?

To compare the effect of Nd:YAG laser capsulotomy and primary posterior continuous capsulorhexis (PPCC) combined with phacoemulsification on macular thickness using optical coherence tomography (OCT) in adults. This prospective comparative interventional study included 32 eyes of 30 patients who underwent Nd:YAG laser capsulotomy and 33 eyes of 33 patients who underwent cataract surgery with PPCC. Detailed ocular examinations, including macular thickness measurements by OCT, were performed in all patients preoperatively and postoperatively on the 1st day, 1st week, and 1st, 3rd and 6th months. No significant differences were found in macular thickness between the two groups in preoperative and postoperative follow-up. No cystoid changes were observed in OCT during the postoperative period in both groups. Nd:YAG laser capsulotomy and PPCC combined with cataract surgery are safe and effective procedures that are not associated with an increase in macular thickness.

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.

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.

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.

Three-hundred-sixty degree barrier effect of a square-edged and an enhanced-edge intraocular lens on centripetal lens epithelial cell migration Two-year results

PURPOSE

To study the 360-degree barrier effect of an intraocular lens (IOL) with a square edge at the optic and an enhanced square edge at the optic-haptic junctions (Rayner 570C C-flex) on centripetal migration of lens epithelial cells (LECs) over a 2-year period.

SETTING

Department of Ophthalmology, Scarborough Hospital, Scarborough, United Kingdom.

METHODS

In a prospective study of 40 consecutive eyes, a C-flex IOL was implanted in the bag after phacoemulsification surgery. Eyes with intraoperative complications, requiring additional procedures, without 360-degree overlap of the optic, or with capsule block syndrome were excluded. Follow-up was at 6, 10, 18, and 24 months. At each visit, high-magnification retroillumination digital photographs were taken using a slitlamp-attached digital camera. The barrier effect to LEC migration across the optic edge and the enhanced square edge at the optic-haptic junction was graded as complete (no epithelial pearls or sheet), partial (few epithelial pearls without sheet), and minimal/none (epithelial sheet behind the IOL optic).

RESULTS

Twenty-four patients came to the final follow-up at 24 months. Fifteen of these eyes (63%) had a complete barrier effect throughout the 360 degrees of the IOL. Three eyes (13%) had a partial barrier effect throughout the 360 degrees of the IOL. Three eyes had a complete optic barrier effect but a partial optic-haptic junction barrier effect. Three eyes had a partial optic barrier effect but a complete optic-haptic junction barrier effect. No eye had epithelial sheets extending behind the optic at any location.

CONCLUSIONS

This study showed the barrier effect of the edge design of the C-flex IOL and the efficacy of the enhanced edge in preventing LEC migration at the optic-haptic junction. The enhanced edge was as effective as a sharp square edge in restricting the LEC migration.

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.

Posterior capsule opacification after implantation of a hydrophilic or a hydrophobic acrylic intraocular lens: one-year follow-up

PURPOSE

To evaluate the effect of hydrophilic and hydrophobic single-piece acrylic intraocular lenses (IOLs) on posterior capsule opacification (PCO) after cataract surgery.

SETTING

St. Erik's Eye Hospital, Stockholm, Sweden.

METHODS

In a prospective study, 120 patients having cataract surgery were randomized to implantation of a hydrophilic acrylic IOL (BL27, Bausch & Lomb) or a hydrophobic acrylic IOL (AcrySof SA60AT, Alcon). Surgery was performed according to a standardized protocol by 1 of 3 surgeons. Best corrected visual acuity, contrast sensitivity, glare, intraocular pressure, and flare were measured 1 week, 3 months, and 1 year after surgery. Posterior capsule opacification was assessed by digital retroillumination photography and analysis using POCOman software at 1 year. The rate of neodymium:YAG (Nd:YAG) capsulotomy for each IOL was also recorded.

RESULTS

At 1 year, the hydrophilic acrylic IOL group had a significantly greater percentage area and severity of PCO than the hydrophobic acrylic IOL group (P<.001). Two patients in the hydrophilic acrylic IOL group and 4 in the hydrophobic acrylic IOL group had an Nd:YAG capsulotomy within the first year (P>.05). Contrast sensitivity was significantly better in the hydrophilic acrylic group at 3 months (P<.05); however, at 12 months no difference between the IOLs was observed. There was no significant difference in the other measured parameters.

CONCLUSION

Patients with the hydrophilic acrylic BL27 IOL had a significantly greater percentage area and severity of PCO than those with the hydrophobic acrylic SA60AT IOL 1 year after surgery.