Evaluation of 3 modern single-piece foldable intraocular lenses: clinicopathological study of posterior capsule opacification in a rabbit model

Two-dimensional ultrathin Ti3C2 MXene nanosheets coated intraocular lens for synergistic photothermal and NIR-controllable rapamycin releasing therapy against posterior capsule opacification

Posterior capsule opacification (PCO) is one of the most frequent late-onset complications after cataract surgery. Several kinds of drug-eluting intraocular lenses (IOL) were designed for sustainable drug release to suppress ocular inflammation, the proliferation of lens epithelial cells (LECs) and the development of PCO after cataract surgery. Despite previous advances in this field, the drug-loaded IOLs were limited in ocular toxicity, insufficient drug-loading capacity, and short release time. To prevent PCO and to address these drawbacks, a novel drug-loaded IOL (Rapa@Ti3C2-IOL), prepared from two-dimensional ultrathin Ti3C2 MXene nanosheets and rapamycin (Rapa), was fabricated with a two-step spin coating method in this study. Rapa@Ti3C2 was prepared via electrostatic self-assembly of Ti3C2 and Rapa, with a loading capacity of Rapa at 92%. Ti3C2 was used as a drug delivery reservoir of Rapa. Rapa@Ti3C2-IOL was designed to have the synergistic photothermal and near infrared (NIR)-controllable drug release property. As a result, Rapa@Ti3C2-IOL exhibited the advantages of simple preparation, high light transmittance, excellent photothermal conversion capacity, and NIR-controllable drug release behavior. The Rapa@Ti3C2 coating effectively eliminated the LECs around Rapa@Ti3C2-IOL under a mild 808-nm NIR laser irradiation (1.0 W/cm−2). Moreover, NIR-controllable Rapa release inhibited the migration of LECs and suppressed the inflammatory response after photothermal therapy in vitro. Then, Rapa@Ti3C2-IOL was implanted into chinchilla rabbit eyes, and the effectiveness and biocompatibility to prevent PCO were evaluated for 4 weeks. The Rapa@Ti3C2-IOL implant exhibited excellent PCO prevention ability with the assistance of NIR irradiation and no obvious pathological damage was observed in surrounding healthy tissues. In summary, the present study offers a promising strategy for preventing PCO via ultrathin Ti3C2 MXene nanosheet-based IOLs with synergistic photothermal and NIR-controllable Rapa release properties.

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.

Modern cataract surgery: unfinished business and unanswered questions

We summarize information, based on clinicopathologic studies over the past decade, on various cataract intraocular lens (IOL) procedures and modern "specialized" IOLs, that will help surgeons continuously improve long-term results for cataract patients. Although most operations do initially provide excellent refractive correction and visual rehabilitation, late complications occur. These sometimes are missed because they are outside of the routine period of follow-up care. We have tried to determine if the various techniques and IOLs truly deliver the long-term results that we desire. Most safety and efficacy information is derived from the manufacturer and is passed through the U.S. Food and Drug Administration (FDA). This is often based on limited, relatively short-term observations made by the manufacturer. After a lens receives FDA approval, there are few means to assess the outcome of each procedure and lens years later. We rarely hear of a 10- or 20-year follow-up study. We have found that one of the best means to assess long-term results is pathologic analyses. We discuss recently studied aspects of pathologic reactions, such as posterior capsule opacification, intracapsular fibrosis, glistenings, intralenticular opacification, and other issues with the various IOL platforms; we then present a clinicopathological overview of tissues and IOLs from our database. These include hydrophobic and hydrophilic acrylic designs, plate lenses, and a dual optic lens.

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.

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.

Quantitative Nachstarevaluierung von Acrylat- und Silikonintraokularlinsen mit scharfem Kantendesign

BACKGROUND

At the Department of Ophthalmology, Heidelberg, Germany, posterior capsule opacification (PCO) of a silicone and an acrylic intraocular lens (IOL) with a sharp optic edge design was evaluated.

PATIENTS AND METHODS

In a prospective study either the AMO ClariFlex silicone IOL or the Sensar AR40e hydrophobic acrylic IOL were implanted in 47 patients following uneventful phacoemulsification. Mean patient age was 76.2+/-7.8 (ClariFlex) and 73.4+/-12.9 years (AR40e), respectively. The mean follow-up time was 19.7+/-5.34 in the ClariFlex and 21.9+/-1.89 months in the AR40e group. PCO development was evaluated postoperatively using the EPCO 2000 analysis software (scale 0-4). Areas of interest were the total IOL optic, the central 3-mm zone as well as the capsulorhexis.

RESULTS

In both groups, all patients achieved a BCVA of 20/32 (AR40e) and 20/25 (ClariFlex), respectively. There was a very low incidence of PCO development with a mean EPCO score of 0.07+/-0.2 (ClariFlex and 0.15+/-0.2 (AR40e). Within the 3-mm zone and the capsulorhexis, there was a tendency for even lower EPCO scores in both groups. We calculated a statistically significant difference for the two lens materials for all investigated IOL areas (Wilcoxon's test, p<0.05).

CONCLUSION

Both IOLs with a sharp edge design showed good functional results, a stable position in the capsular bag as well as a low incidence of PCO development. However, the silicone IOL showed statistically significantly lower PCO scores.

[Influence of intraocular lens material and design on the development of posterior capsule opacification]

Based on the literature of 1999-2005, we attempted to clarify the influence of material and design of an intraocular lens (IOL) on the development of posterior capsule opacification (PCO) and identify the future problems to be solved. The sharp edge design of an IOL has significantly reduced PCO in recent years. Histopathological studies showed that a sharp capsular bend was formed at the sharp posterior optic edge, and the migration of lens epithelial cells was obviously inhibited at the site. Experimental and clinical studies suggest that the sharper the edge is, the sharper the capsular bend, and the greater the preventive effect, regardless of IOL material. The sharp capsule bend appears to represent a physical hindrance, which may induce contact inhibition of cell movement. How material participates in the preventive effect should be clarified in a future study. Thus, at the moment, the formation of capsular bend at the posterior optic edge appears to be the decisive criterion to evaluate the influence of IOL material and design on the development of PCO. Optimization of design and material of an IOL, which facilitates capsular bend formation as sharply and quickly as possible, may reduce PCO to a clinically negligible level.

Posterior capsule opacification in rabbit eyes implanted with 1-piece and 3-piece hydrophobic acrylic intraocular lenses

PURPOSE

To evaluate the outcome of posterior capsule opacification (PCO) after implantation in rabbit eyes of currently available 3-piece and 1-piece hydrophobic acrylic intraocular lenses (IOLs) with square optic edges.

SETTING

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

METHODS

The 3-piece designs evaluated were the AR40e (Advanced Medical Optics Inc.) and the MA60AC (Alcon, Inc.); the 1-piece designs were the SA60AT and the SA30AT (Alcon, Inc.). Nine lenses of each type were implanted in a randomized manner by the same surgeon in 18 Dutch Belted pigmented rabbits. After a follow-up of 3 weeks, the rabbits were killed and analyses of the enucleated eyes were performed from the posterior or Miyake-Apple view. The intensity of central PCO, peripheral PCO, and Soemmering's ring formation was scored from 0 to 4. The area of Soemmering's ring formation was also scored from 0 to 4 based on the number of quadrants involved. Other parameters analyzed were capsulorhexis coverage of the IOL anterior surface, IOL centration, fixation, and presence of striae. Results from the posterior view were complemented by histopathologic evaluation of the eyes.

RESULTS

No statistically significant difference was found between the 4 groups of IOLs in the parameters analyzed from the posterior view. When cell ingrowth occurred with the 1-piece designs, causing peripheral and central PCO formation, it was more likely to start at the optic-haptic junctions, as observed during the clinical follow-up with slitlamp examination and confirmed by gross and histopathologic analyses of the enucleated eyes.

CONCLUSIONS

The square, truncated optic edge is the most important IOL design feature for PCO prevention. The optic-haptic junctions of the 1-piece designs appear to be sites where the barrier effect of the truncated optic edge is less effective.

Comparison of posterior capsule opacification rates between hydrophilic and hydrophobic single-piece acrylic intraocular lenses

PURPOSE

To determine the effect of intraocular lens (IOL) material on the development of posterior capsule opacification (PCO) at 1 year.

SETTING

Department of Ophthalmology, St. Thomas' Hospital, London, United Kingdom.

METHODS

One hundred six eyes of 53 patients with bilateral cataract and no other ocular comorbidity were prospectively randomized to receive a hydrophobic acrylic or hydrophilic acrylic single-piece IOL in the first eye to have surgery. The alternate IOL was implanted in the fellow eye 4 to 6 weeks later. All surgery was performed by a single surgeon. Postoperative follow-up was 1 day, 1 and 6 months, and 1 year. At each visit, the best corrected high- and low-contrast visual acuities were assessed and a high-intensity digital retroillumination photograph was taken. Posterior capsule opacification was assessed from the digital images by a single operator using a dedicated software program and calculated as the percentage area of opacified capsule.

RESULTS

One year postoperatively, the median percentage area of PCO was 50.3% in the hydrophilic IOL group and 4.9% in the hydrophobic IOL group (P<.001). The difference in PCO was not accounted for by loss of contact between the capsulorhexis and IOL surface. Further analysis showed that lens epithelial cells tended to invade the posterior capsule at the haptic-optic junction. This was more marked in the hydrophilic IOL group.

CONCLUSIONS

The rate of PCO was significantly higher with the hydrophilic IOL. However, the results cannot be attributed to the IOL material alone as they show the importance of both IOL material and design.

Posterior capsule opacification in rabbit eyes implanted with hydrophilic acrylic intraocular lenses with enhanced square edge

PURPOSE

To evaluate the development of posterior capsule opacification (PCO) after implantation of single-piece hydrophilic acrylic intraocular lenses (IOLs) with an enhanced square edge.

SETTING

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

METHODS

The standard 570H Centerflex (Rayner Ltd.) design was compared to 2 new designs with enhanced square edges: the 570E and the 570C. Ten IOLs of each type were implanted in a randomized manner by the same surgeon in 15 pigmented rabbits. After a follow-up of 3 weeks, the rabbits were killed and the eyes were analyzed from the posterior view. The intensity of central PCO, peripheral PCO, and Soemmering's ring formation was graded from 0 to 4. The area of Soemmering's ring was graded from 0 to 4 based on the number of quadrants involved. Other parameters analyzed were capsulorhexis coverage of the IOL edge and IOL centration and fixation. Results from the posterior view were complemented by histopathological evaluation.

RESULTS

Posterior capsule opacification was lowest in the 570C group, highest in the 570H group, and intermediate in the 570E group. There was a statistically significant difference between the 3 groups in peripheral PCO (P = .039). No significant difference was found between the groups in the other parameters analyzed. When cell ingrowth occurred with the 570H, it started at the optic-haptic junctions, as observed during the clinical follow-up and confirmed by gross and histopathological analyses.

CONCLUSIONS

The square optic edge is the most important IOL design feature for PCO prevention. However, it should be present for 360 degrees around the IOL optic to provide an effective barrier effect.

Evaluation of a human capsular bag model for secondary cataract determination after intraocular lens implantation

PURPOSE

To investigate the effect of different intraocular lenses (IOLs) on lens epithelial cells (LECs) and on human capsular bags in vitro and to evaluate the transferability of this model to clinical situations.

METHODS

Sham cataract surgery, including IOL-into-the-bag implantation, was performed on 38 donor eyes after removal of the cornea. The capsular bag including the IOL was removed, pinned on a culture dish, covered with medium, and incubated. Two different IOLs were compared per pair of donor eyes. In each pair of donor eyes, the two different IOLs to be compared were implanted individually into capsular bags. The time required for complete coverage of the posterior capsule by a confluent monolayer of LECs was documented. The following IOLs were compared: three-piece acrylic IOLs of different sizes and single-piece polymethylmethacrylate (PMMA) versus acrylic IOLs.

RESULTS

A complete monolayer of LECs on the posterior capsule was observed to form at times varying from 8 days (PMMA IOLs) to more than 60 days (three-piece hydrophobic acrylic IOLs). A significant difference between PMMA IOLs and hydrophobic acrylic IOLs was found.

CONCLUSIONS

The human capsular bag model employed allows short-term evaluation of secondary cataract formation for different IOLs. This model's correlation with clinical results is good.

A prospective, randomised comparison of single and three piece acrylic foldable intraocular lenses

AIMS

To compare the postoperative performance of single and three piece acrylic foldable intraocular lenses (IOLs).

METHODS

20 patients underwent bilateral cataract surgery with a single piece SA30AL IOL in one eye and a three piece MA30BA IOL in the other eye. The eyes were randomly assigned to either a single or three piece lens. The amount of IOL decentration and tilt, area of anterior capsule opening, and degree of posterior capsule opacification were measured using the Scheimpflug anterior segment analysis system (Nidek EAS-1000). Visual acuity and contrast sensitivity were examined. Measurements were performed by masked examiners before and 1 day, 1 week, 1, 3, 6, and 18 months after surgery.

RESULTS

There were no significant differences between the two groups (p>0.05, paired t test) in the amount of IOL decentration, IOL tilt, area of anterior capsule opening, degree of posterior capsule opacification, best corrected visual acuity, and contrast sensitivity throughout the 18 month follow up period.

CONCLUSION

The single and three piece acrylic foldable IOLs are equally stable in the eye after surgery.

Implantation of a single-piece, hydrophilic, acrylic, minus-power foldable posterior chamber intraocular lens in a rabbit model: clinicopathologic study of posterior capsule opacification

PURPOSE

To compare the extent of posterior capsule opacification (PCO) after implantation of a standard-power biconvex Centerflex intraocular lens (IOL) and a newly introduced biconcave high-minus-power Centerflex design in rabbit eyes.

SETTING

The Center for Research on Ocular Therapeutics and Biodevices, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, and the David J. Apple, MD, Laboratories for Ophthalmic Devices Research, John A. Moran Eye Center, University of Utah School of Medicine, Salt Lake City, Utah, USA.

METHODS

Twelve rabbits had phacoemulsification and implantation of 2 foldable single-piece hydrophilic acrylic Centerflex posterior chamber IOLs. The right eyes received a standard-power (+21.00 diopters [D]) biconvex-optic lens and the left eyes, a minus-power (-7.00 D) biconcave-optic IOL. Formation of PCO was evaluated 3 weeks after surgery using the Miyake-Apple posterior photography technique. Histological sections from each globe were prepared to analyze capsular bag status and assess postsurgical intracapsular lens epithelial cell (LEC) proliferation, especially ingrowth of LECs across the visual axis. The data were analyzed using the Kruskal-Wallis 1-way analysis of variance for nonparametric measurements and the Mann-Whitney rank sum test.

RESULTS

There was no significant difference in Soemmering's ring formation between the 2 IOL models. The biconcave minus-power IOL showed significantly lower central and peripheral PCO scores than the biconvex standard-power lens (P<.05). Pathological evaluations revealed that the effective site of blockage of LECs was at the truncated optic edge of both lenses, even in the presence of retained and/or regenerative cortical material.

CONCLUSIONS

This study confirms the efficacy of a truncated IOL optic in helping reduce the incidence of PCO. Both IOL designs have optic geometries that create clear-cut barrier effects. However, the biconcave minus-power IOL, which has a thicker, square, truncated optic edge with a ridge that encircles the periphery of the optic for 360 degrees, appears to have an enhanced barrier effect, especially at the optic-haptic junction. This further minimizes the ingrowth of migrating LECs toward the visual axis.

Pharmacologic prevention of posterior capsule opacification: in vitro effects of preservative-free lidocaine 1% on lens epithelial cells

PURPOSE

To assess the in vitro effectiveness of preservative-free lidocaine 1% in removing lens epithelial cells (LECs) from the anterior capsule and to evaluate the effect of lidocaine on the LECs.

SETTING

Center for Research on Ocular Therapeutics and Biodevices, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA.

METHODS

Eight rabbits (16 eyes) were used in the study. After the rabbits were killed, the eyes were enucleated and divided into 2 groups. In Group 1 (n = 8 eyes), LECs were exposed to preservative-free lidocaine 1% or balanced salt solution (BSS) for 1, 2, or 5 minutes. The anterior capsules were then stained with trypan blue and alizarin red. Photomicrographs of each capsule were taken and analyzed for LEC damage. In Group 2 (n = 8 eyes), hydrodissection was performed with 1 of the agents, followed by phacoemulsification and cortical cleanup. The LEC attachment to the anterior capsule was evaluated by histopathology.

RESULTS

Anterior capsule fragments irrigated with BSS showed no LEC nuclear staining; ie, no direct toxic effect. In those irrigated with preservative-free lidocaine 1%, the LECs showed mild toxicity; some cells showed blue nuclear staining. After hydrodissection with lidocaine, the capsules were almost free of LECs; after hydrodissection with BSS, the capsules showed a normal layer of LECs attached to the anterior capsule.

CONCLUSIONS

Preservative-free lidocaine 1% may help diminish the amount of live LECs by facilitating cortical cleanup, by loosening the desmosomal area of cell-cell adhesion with decreased cellular adherence, or by a direct toxic effect. The use of this agent may help prevent posterior capsule opacification.

Cataract treatment in the beginning of the 21st century

PURPOSE

To describe the principles upon which present day cataract treatment success resides.

DESIGN

Literature review and collective experience of the authors.

RESULTS

Surgical removal remains the standard treatment for cataract now and in the foreseeable future. Ultrasound cataract removal with a foldable "in-the-bag" intraocular lens with a truncated edge treated for dysphotopsia best correlates with core treatment principles, as we now understand them. Improving refractive results is an important trend. The worldwide burden of this problem is immense.

CONCLUSIONS

While results for treatment of cataracts are excellent today, improvements in safety and refraction precision are needed. Other approaches are desperately needed to stem the worldwide tide of cataract related ocular dysfunction.