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

Posterior Capsule Opacification after Cataract Surgery via Implantation with Hydrophobic Acrylic Lens Compared with Silicone Intraocular Lens: A Systematic Review and Meta-Analysis

Hydrophobic acrylic intraocular lens (IOL) is the most popular material in cataract surgery. Posterior capsule opacification (PCO) is a long-term complication of cataract surgery. It can impair vision and adversely affect the prognosis of IOL delamination. The objective of this study was to perform a systematic review and meta-analysis to provide an updated evaluation of long-term complications and visual function after implantation with hydrophobic acrylic and silicone intraocular lenses. PubMed, Embase, and Cochrane Library were searched from January 2000 until March 2021. Randomized controlled trials (RCTs) and retrospective studies were finally included. The main outcomes were PCO value and neodymium-doped yttrium aluminum garnet (Nd : YAG) capsulotomy rate. Subgroup analysis was performed to compare hydrophobic acrylic and silicone IOLs during the follow-up period. Sensitivity analysis was also performed. The meta-analysis included a total of 17 studies. When the follow-up period was considered, the results of the analysis revealed higher PCO value (Group 3: standardized mean difference (SMD), −0.59; 95% confidence interval (CI), −0.90 to −0.28) and Nd : YAG capsulotomy rate (Group 3: risk ratio (RR), 0.60; 95% CI, 0.40–0.89) for hydrophobic acrylic IOLs than silicone IOLs during a long-term (≥6 years) follow-up. In conclusion, both the PCO value and the Nd : YAG capsulotomy rates were higher in hydrophobic acrylic IOLs group than the silicone IOLs group at long-term use (more than 6 years) after implantation.

Comparison of Clinical Outcomes, Visual Quality and Visual Function of Two Presbyopia-Correcting Intraocular Lenses Made from the Same Material, but with Different Design and Optics

This semi-prospective, parallel, comparative investigation evaluated the clinical outcomes and quality of vision (contrast sensitivity, visual function, dysphotopsia, spectacle use, overall satisfaction) after mono- or bilateral implantation of two presbyopia-correcting intraocular lenses (IOL)-the Liberty® 677MY or the AT LISA® tri 839M-in 50 eyes of 25 cataract patients. Clinical outcomes were assessed 3 and 12 months postoperatively. Eighty-nine percent of eyes implanted with the Liberty IOL and 59% of eyes implanted with the AT LISA IOL achieved a refractive outcome ±0.5 diopters of the target (emmetropia). Refractive outcomes were stable with both lenses. The proportions of eyes with 20/20 uncorrected distance visual acuity (UDVA) and 20/20 uncorrected near visual acuity (UNVA) were higher in the Liberty group than in the AT LISA group (UDVA: 56% vs. 41%; UNVA: 83% vs. 66%). Optical quality assessment results were comparable for the two IOLs. Superior photopic contrast sensitivity was found with the Liberty lens. The rate of Nd:YAG capsulotomy at the 12-month follow-up was 16.7% in the Liberty group and 40.6% for the AT LISA IOL. Considering that both lenses are made from the same material, we propose that the noted differences in clinical outcomes may derive from differences in design and optical surface between the two IOLs.

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.

Incidence of posterior capsular opacification requiring Nd:YAG capsulotomy after cataract surgery and implantation of enVista® MX60 IOL

PURPOSE

To evaluate incidence of posterior capsule opacification requiring Nd:YAG capsulotomy over 3 years in a large series of eyes implanted with the enVista^® MX60 Intraocular Lens (IOL).

METHODS

A university-based, single-center, observational study of patients' medical records was conducted. Uneventful cataract surgery patients with in-the-bag implantations of the enVista^® MX60 IOL with a minimum of 24 months follow-up were included in the study. Exclusion criteria were insufficient follow-up (<24 months), intraoperative complications and combined surgery. The primary outcome measure was rate of YAG laser capsulotomy, while secondary outcome measures were time to YAG laser capsulotomy and rate of glistenings.

RESULTS

A total of 245 eyes of 143 patients received the MX60 IOL and were followed in the same center. Of these, 226 eyes were included in the study. Mean age was 80.7±8.3 years and M/F ratio was 42/101 (29.4/70.6%). The mean preoperative distance (logMAR) visual acuity was 0.67±0.5, while postoperatively it was 0.31±0.5 and 0.32±0.5 at the last visit. The Mean±SD follow-up time (min-max) was 35.2±7.2, (24-48.4) months. The incidence of Nd:YAG capsulotomy over 3 years was 5/226 (2.2%). Average time between surgery and Nd:YAG capsulotomy was 32.17 months. Univariate analysis of age, gender, presence of comorbidity and baseline visual acuity found no predictive factors for capsulotomy. No glistenings were reported at any postoperative visit.

CONCLUSION

The three-year cumulative incidence of PCO requiring Nd:YAG laser capsulotomy was 2.2% for the enVista^® MX-60 IOL, with no glistenings observed during follow-up. This low rate confirms the excellent safety profile of this IOL.

Biocompatibility of Intraocular Lenses

The performance of an intraocular lens is determined by several factors such as the surgical technique, surgical complications, intraocular lens biomaterial and design, and host reaction to the lens. The factor indicating the biocompatibility of an intraocular lens is the behavior of inflammatory and lens epithelial cells. Hence, the biocompatibility of intraocular lens materials is assessed in terms of uveal biocompatibility, based on the inflammatory foreign-body reaction of the eye against the implant, and in terms of capsular biocompatibility, determined by the relationship of the intraocular lens with residual lens epithelial cells within the capsular bag. Insufficient biocompatibility of intraocular lens materials may result in different clinical entities such as anterior capsule opacification, posterior capsule opacification, and lens epithelial cell ongrowth. Intraocular lenses are increasingly implanted much earlier in life in cases such as refractive lens exchange or pediatric intraocular lens implantation after congenital cataract surgery, and these lenses are expected to exhibit maximum performance for many decades. The materials used in intraocular lens manufacture should, therefore, ensure long-term uveal and capsular biocompatibility. In this article, we review the currently available materials used in the manufacture of intraocular lenses, especially with regard to their uveal and capsular biocompatibility, and discuss efforts to improve the biocompatibility of intraocular lenses.

Epidemiological evaluation of YAG capsulotomy incidence for posterior capsule opacification in various intraocular lenses in Japanese eyes

Background and objective

We investigated the yttrium aluminum garnet (YAG) capsulotomy rates in various intraocular lenses (IOLs).

Study design/patients and methods

We retrospectively analyzed 23,440 eyes implanted with either MA60BM, MA60AC, VA-60BB, CeeOnEdge, Clariflex, Technis Z9002, SI-40NB, or UV26T IOLs. We calculated the YAG capsulotomy rates at 1, 3, 5, and 10 years post lens implantation.

Results

YAG capsulotomy rates at 3 years postimplantation for the eight groups of IOLs were, respectively, 3.7%, 3.9%, 23.7%, 3.4%, 4.5%, 4.7%, 10.4%, and 21.0%. YAG capsulotomy rates at 10 years postimplantation for the MA60BM and SI-40NB IOLs were, respectively, 9.1% and 15% (P<0.05). The average YAG rates for all sharp-edged and round-edged IOLs at 5 years postimplantation were, respectively, 5.2%±0.7% and 25.6%±9.0% (P<0.05).

Conclusion

In all studied IOLs, posterior capsule opacification prevention seemed to be associated with the posterior optic sharp-edge design. Round-edged silicone IOLs may also retard posterior capsule opacification formation, though not as much as sharp-edged IOLs. As the follow-up period progressed, round-edged silicone IOLs showed significantly higher YAG rates than sharp-edged IOLs.

Comparison of posterior capsule opacification at 360-degree square edge hydrophilic and sharp edge hydrophobic acrylic intraocular lens in diabetic patients

AIM

To compare posterior capsule opacification (PCO) degree and visual functions after phacoemulsification in eyes implanted with 360-degree square edge hydrophilic acrylic intraocular lens (IOL) (570C C-flex, Rayner) and sharp edge hydrophobic acrylic IOL (Sensar AR40e, AMO) in diabetic patients.

METHODS

Sixty diabetic patients underwent uneventful phacoemulsification and randomly implanted one of the two IOLs. The PCO value was measured by retroillumination photographs and Evaluation of Posterior Capsule Opacification (EPCO) 2000 image-analysis software at 1, 6, 12, and 24mo after surgery. Visual acuity, and contrast sensitivity in photopic and mesopic conditions were also examined at each follow up time point. The incidence of eye that required Nd:YAG laser posterior capsulotomy were also compared.

RESULTS

There was not any statistically significant difference in PCO scores between Rayner C-flex 570C group and Sensar AR40e group at each follow up time point. Visual acuity, Nd:YAG capsulotomy incidence and contrast sensitivity also had no significant difference during the 24mo follow-up.

CONCLUSION

For diabetic patients, Rayner 570C C-flex and Sensar AR40e IOLs are same effective for prevent PCO. The 360-degree square edge design maybe is a good alternative technique to improve PCO prevention.

Five-year postoperative outcomes of apodized diffractive multifocal intraocular lens implantation

PURPOSE

To assess the long-term postoperative visual performance of an apodized diffractive multifocal intraocular lens (IOL).

METHODS

Twenty-one patients (42 eyes) underwent cataract surgery with bilateral implantation of an apodized diffractive multifocal IOL. The monocular uncorrected and corrected distance visual acuities, uncorrected, distance-corrected and corrected near visual acuities, and manifest refractive spherical equivalent were measured 1 and 5 years postoperatively. The contrast sensitivity, incidence of glare or halos, and rate of neodynium:YAG (Nd:YAG) posterior capsulotomy were evaluated 5 years postoperatively.

RESULTS

No significant differences were found between the distance and near visual acuities at 1 and 5 years postoperatively. The contrast sensitivity was within the normal range for all spatial frequencies. No patients reported severe glare or halos. Six (14.3 %) eyes required Nd:YAG posterior capsulotomy.

CONCLUSIONS

The apodized diffractive multifocal IOL provides good, stable distance and near visual acuity levels over a 5-year follow-up period.

The impact of capsulorhexis diameter, localization and shape on posterior capsule opacification

BACKGROUND

The aim of this study was to evaluate the impact of capsulorhexis diameter, localization and shape on posterior capsule opacification (PCO) development after cataract extraction with phacoemulsification.

MATERIAL/METHODS

We retrospectively analyzed of 297 patients who underwent phacoemulsification and AcrySof SA60AT implantation. In a first group of 97 patients, 53 received small capsulorhexis (3.9 to 4.9 mm in diameter) and 44 patients received large capsulorhexis (5.0 to 5.9 mm in diameter). Another group of 99 patients was split into subgroups--66 patients whose capsulorhexis were centrally located and 33 patients whose capsulorhexis were paracentral. A third group of 101 patients was split into subgroups--a subgroup of 59 patients were classified as having a regularly rimmed capsulorhexis and a subgroup of 42 patients as having an irregularly rimmed capsulorhexis. At 6 months follow-up, PCO was classified as none, mild, moderate, or severe, depending on the number of quadrants involved.

RESULTS

86.79% of the patients with a small capsulorhexis had no or mild PCO (p<0.001), whereas, 68.18% of the patients with a large capsulorhexis experienced moderate or severe PCO; 89.4% of the patients with a central capsulorhexis had no or mild PCO (p<0.001), whereas, 75.75% of the patients with a paracentral capsulorhexis had moderate or severe PCO; 86.44% of the patients with a regularly rimmed anterior capsulorhexis had no or mild PCO (p<0.001); and 69.04% of the patients with an irregular capsulorhexis rim had moderate or severe PCO.

CONCLUSIONS

A small capsulorhexis diameter, its central localization and regular shape result in less PCO following phacoemulsification.

Anterior capsule relaxing incisions with neodymium:YAG laser for patients at high-risk for anterior capsule contraction

PURPOSE

To examine the effect of anterior capsule relaxing incisions created with a neodymium:YAG (Nd:YAG) laser on prevention of anterior capsule contraction after cataract surgery in high-risk patients.

SETTING

Hayashi Eye Hospital, Fukuoka, Japan.

DESIGN

Randomized masked clinical trials.

METHODS

Patients at high risk for anterior capsule contraction had anterior capsule relaxing incisions in either eye 3 days postoperatively. The anterior capsule opening was measured using a Scheimpflug videophotography system (EAS-1000) immediately and 1, 3, and 6 months after capsulotomy, and the percentage reduction in area was calculated. The degree of intraocular lens (IOL) decentration and tilt, posterior capsule opacification (PCO), and other complications were also assessed.

RESULTS

Of the 84 patients included, 30 had primary angle closure, 28 had pseudoexfoliation, and 26 had diabetic retinopathy. There was no significant difference in the mean opening area between fellow eyes at baseline. In patients with primary angle closure, the area was significantly greater and the percentage reduction in area was significantly less in the capsulotomy group than in the no-capsulotomy group (P≤.0428). In patients with pseudoexfoliation or diabetic retinopathy, the percentage reduction was significantly less in the capsulotomy group than in the no-capsulotomy group (P≤.0493), although there was no significant difference in area. No significant difference was found in IOL decentration or tilt, PCO, or incidence of other complications.

CONCLUSION

Neodymium:YAG laser anterior capsule relaxing incisions in the early period after cataract surgery were effective in preventing anterior capsule contraction in high-risk patients and had no adverse effects.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned.

Biconvex posterior chamber accommodating intraocular lens implantation after cataract surgery: long-term outcomes

PURPOSE

To evaluate the long-term efficacy of a biconvex accommodating intraocular lens (IOL) to restore near visual performance.

SETTING

Department of Ophthalmology, Keio University Hospital, Tokyo, Japan.

METHODS

This 4-year study comprised eyes that had cataract surgery with implantation of a 1CU accommodating IOL. At all postoperative visits, the following were assessed: subjective spherical equivalent (SE) refraction; uncorrected (UDVA) and corrected (CDVA) distance visual acuities; uncorrected (UNVA), distance-corrected (DCNVA), and corrected (CNVA) near visual acuities; change in minimum additional (add) power (diopters) to attain CNVA; and accommodation amplitude. A questionnaire was administered at the last visit.

RESULTS

Twelve eyes of 8 cataract patients (mean age 59.0 years +/- 18.4 [SD]) were evaluated. Postoperatively, the mean SE at 1 year and 4 years was significantly more hyperopic than at 1 month (P<.05). The mean UDVA increased significantly at 4 years compared with 1 month (P<.05). There were no significant changes in CDVA, UNVA, CNVA, and DCNVA throughout the follow-up period. The change in the minimum add power to attain CNVA and in the subjective and objective accommodation amplitudes also did not change significantly over time. Eighty-three percent of patients reported being satisfied with the results.

CONCLUSION

Four years after implantation of an accommodating IOL, most patients had good vision and were satisfied, although the accommodation amplitude for near vision was not sufficient throughout the follow-up.

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.

Biocompatibility of intraocular lens materials

PURPOSE OF REVIEW

To provide an update on currently available materials used in the manufacture of intraocular lenses, as well as new materials under development, especially with regard to their uveal and capsular biocompatibility.

RECENT FINDINGS

The biocompatibility of intraocular lens materials should be assessed in terms of uveal biocompatibility, related to the inflammatory foreign-body reaction of the eye against the implant, as well as in terms of capsular biocompatibility, determined by the relationship of the intraocular lens with remaining lens epithelial cells within the capsular bag. This situation may result in different entities, e.g. anterior capsule opacification, interlenticular opacification (between piggyback intraocular lenses), posterior capsule opacification and lens epithelial cell ongrowth. Reports on intraocular lens opacification suggest that the potential to calcify should also be taken into consideration when evaluating the long-term biocompatibility of a new material.

SUMMARY

Intraocular lenses are being progressively implanted in much earlier stages of life (refractive lens exchange, pediatric implantation) and are expected to remain in the intraocular environment for many decades. Materials used in intraocular lens manufacture should, therefore, insure long-term uveal and capsular biocompatibility, as well as ultimate transparency after implantation.