Long-term incidence of posterior capsular opacification in patients with non-infectious uveitis

Little is known about the long-term incidence of posterior capsule opacification (PCO) after cataract surgery in patients with uveitis. This retrospective study included 211 eyes of 146 patients with non-infectious uveitis who underwent cataract surgery and implantation of an Acrysof SN60WF (Surface: plasma-treated, Optic and Haptic: hydrophobic acrylic), iSert XY-1 (Surface: UV-ozone-treated, Optic and Haptic: hydrophobic acrylic), or iSert 251/255 (Surface: UV-ozone-treated, Optics: hydrophobic acrylic, Haptic: polymethyl methacrylate). The cumulative incidences of PCO and subsequent yttrium–aluminum-garnet (Nd:YAG) capsulotomy over the 5-year follow-up were analyzed, and patients who were implanted with different intraocular lenses (IOLs) were compared. Mixed-effects Cox proportional hazard models showed that, compared with the Acrysof group, the iSert XY-1 group had higher risks of PCO (adjusted HR, 7.26; 95% CI, 1.82–28.8) and Nd:YAG capsulotomy (adjusted HR, 6.50; 95% CI, 1.55–27.2). Similar results were obtained when the Acrysof group was compared with the iSert 251/255 group for PCO (adjusted HR, 8.22; 95% CI, 2.35–28.7) and Nd:YAG capsulotomy (adjusted HR, 8.26; 1.90–36.0). These data suggest that a plasma-treated surface, hydrophobic acrylic optic and hydrophobic acrylic haptic, of the IOL could enhance biocompatibility even under inflammatory conditions, thus suppressing PCO development.

Comparison Study of Anterior Capsule Contraction of Hydrophilic and Hydrophobic Intraocular Lenses Under the Same Size Capsulotomy

Purpose

To compare anterior capsule contraction of two kinds of hydrophilic and hydrophobic acrylic intraocular lenses (IOLs) under the same size capsulotomy with femtosecond laser-assisted cataract surgery (FLACS).

Methods

A total of 320 eyes in 320 patients who underwent FLACS were included. The patients were scheduled to have hydrophilic acrylic IOLs (MI60, 509M) and hydrophobic acrylic IOLs (iSert250, ZCB00) implanted. Visual acuity and anterior segment photography using a slit lamp microscope were performed at postoperative one week, one month, three months, and one year.

Results

The contraction of the anterior capsule opening area (mm²) and circumference (mm) in the hydrophilic group were larger than that of the hydrophobic group from postoperative one week to one year (P < 0.001, P < 0.001, respectively). The postoperative contraction of the capsule opening area in MI60 was larger than in 509M (P < 0.001) and larger in 509M than in iSert250 and ZCB00 (P = 0.008, P = 0.019, respectively), but no difference was observed between iSert250 and ZCB00 (P = 0.867). During postoperative one to three months, all groups had the maximum capsule contraction (P < 0.001).

Conclusions

Under the same size capsulotomy with FLACS, the postoperative anterior capsule contraction induced by hydrophobic IOLs was less than that induced by hydrophilic IOLs. Among the four IOLs, the capsule contraction was largest in MI60, followed by 509M, and least in iSert250 and ZCB00, which was time-dependent.

Translational Relevance

Our findings implied that patients with a high risk of ACC should choose hydrophobic IOLs, as well as nonsteroidal anti-inflammatory drugs may be used for a longer period in patients with high risk of capsule contraction syndrome.

Cataract inhibitors: Present needs and future challenges

Cataracts result from opacification of the ocular lens and represent the leading cause of blindness worldwide. After surgical removal of the diseased lens material and implantation of an artificial intraocular lens, up to 50% of cataract patients develop a secondary lens defect called posterior capsular opacification (PCO). While vision can be restored in PCO patients by a laser-mediated capsulotomy, novel therapies involving inhibition of aldose reductase are now being developed to prevent PCO development and complications of laser capsulotomy. A question we wished to address was whether cataract surgeons believe there is an unmet need for a preventative PCO therapy, whether they would prescribe such a therapy were it available, and to assess their perceptions regarding the benefits of and obstacles to adopting novel PCO therapies in the place of laser capsulotomy. We gathered perspectives from adult, pediatric, and veterinary cataract surgeons using an online questionnaire. From 161 surgeon responses, we found that the majority of adult, pediatric, and veterinary cataract surgeons (78% n = 35, 88% n = 37, and 96% n = 71 respectively) believed there is an unmet need for preventative PCO therapy, with more than 95% expressing interest in incorporating such therapy into surgical protocols. Perceived benefits included optimizing visual outcomes, avoiding the need for additional procedures, eliminating complications related to neodymium:yttrium-aluminum-garnet laser, preserving the posterior capsule particularly in patients receiving multifocal intraocular lens implants, providing a viable solution for PCO in animals, and using it in developing countries that lack access to neodymium:yttrium-aluminum-garnet lasers. Perceived obstacles included potential lack of reimbursement by insurance companies, and the need for strong efficacy and safety profiles. Among adult surgeons, 70% (n = 31) indicated that preventative PCO therapy could add value to premium intraocular lens packages. Our studies revealed that cataract surgeons overwhelmingly support the development of preventative PCO therapy, and that clinical trials will play a critical role to test the safety and efficacy of specific therapeutic agents.

Foldable Glistening-Free Acrylic Intraocular Lens Biomaterials with Dual-Side Heterogeneous Surface Modification for Postoperative Endophthalmitis and Posterior Capsule Opacification Prophylaxis

Hydrophobic acrylic intraocular lenses (IOLs) are widely used in cataract treatment for posterior capsule opacification (PCO) prophylaxis. However, undesired glistening and postoperative endophthalmitis are two major potential risks. Hence, a series of poly(2-phenoxyethyl methacrylate-co-2-phenoxyethyl acrylate-co-2-ethylhexyl methacrylate) (PPPE) acrylic IOL materials were synthesized for "glistening-free" optimization. The selected PPPE with 2% 2-ethylhexyl methacrylate showed excellent optical, foldable, and thermomechanical properties. The anterior surface of PPPE was coated with polydopamine followed by gentamycin conjugation (PDA/GS). It inhibited bacterial adhesion by 74% and decreased the biofilm thickness by 87%. In inflammatory mimicking conditions, bacterial proliferation was restrained, with acidic-dependent GS release behavior. The surface of PPPE toward the posterior capsule remained hydrophobic. It was conducive to human lens epithelial cell adhesion, collagen IV and fibronectin adsorption, and the following "sealed sandwich structure" formation. In summary, the PPPE with a dual-side heterogeneous surface displayed good application prospects in postoperative endophthalmitis and PCO prevention.

Evaluating the Biostability of Yellow and Clear Intraocular Lenses with a System Simulating Natural Intraocular Environment

PURPOSE

Blue light-filtering intraocular lenses (IOLs) are thought to protect the retina from blue light damage after cataract surgery, and the implantation of yellow-tinted IOLs has been commonly used in cataract surgery. To our knowledge, this is the first investigation measuring the long-term biostability of yellow-tinted IOLs using an in vitro system simulating natural intraocular environment.

METHODS

Six hydrophobic acrylic IOLs, three clear IOLs, and three yellow-tinted IOLs were included in the study. Each yellow-tinted IOL was a matching counterpart of a clear IOL, with the only difference being the lens color. The IOLs were kept in conditions replicating the intraocular environment using a perfusion culture system for 7 months. Resolution, light transmittance rate, and the modulation transfer function (MTF) were measured before and after culturing. Surface roughness of the anterior and posterior surfaces was also measured.

RESULTS

After culturing for 7 months, there were no changes in the resolution, the light transmittance rate, and MTF. The surface roughness of the anterior and posterior surfaces increased after culturing; however, this increase was clinically insignificant. There were no differences in surface roughness between the clear and yellow-tinted IOLs, either before or after culturing.

CONCLUSIONS

A novel in vitro system replicating intraocular environment was used to investigate the biostability of yellow-tinted IOLs. The surface roughness showed no clinically significant increase after culturing for 7 months.

TRANSLATIONAL RELEVANCE

This system is useful for evaluating the biostability of IOLs.

Sustained-release genistein from nanostructured lipid carrier suppresses human lens epithelial cell growth

AIM

To design and investigate the efficacy of a modified nanostructured lipid carrier loaded with genistein (Gen-NLC) to inhibit human lens epithelial cells (HLECs) proliferation.

METHODS

Gen-NLC was made by melt emulsification method. The morphology, particle size (PS), zeta potentials (ZP), encapsulation efficiency (EE) and in vitro release were characterized. The inhibition effect of nanostructured lipid carrier (NLC), genistein (Gen) and Gen-NLC on HLECs proliferation was evaluated by cell counting kit-8 (CCK-8) assay, gene and protein expression of the proliferation marker Ki67 were evaluated with real-time quantitative polymerase chain reaction (RT-qPCR) and immunofluorescence analyses.

RESULTS

The mean PS of Gen-NLC was 80.12±1.55 nm with a mean polydispersity index of 0.11±0.02. The mean ZP was -7.14±0.38 mV and the EE of Gen in the nanoparticles was 92.3%±0.73%. Transmission electron microscopy showed that Gen-NLC displayed spherical-shaped particles covered by an outer-layer structure. In vitro release experiments demonstrated a prolonged drug release for 72h. The CCK-8 assay results showed the NLC had no inhibitory effect on HLECs and Gen-NLC displayed a much more prominent inhibitory effect on cellular growth compared to Gen of the same concentration. The mRNA and protein expression of Ki67 in LECs decreased significantly in Gen-NLC group.

CONCLUSION

Sustained drug release by Gen-NLCs may impede HLEC growth.

Intraindividual comparative analysis of capsule opacification after implantation of 2 single-piece hydrophobic acrylic intraocular lenses models: Three-year follow-up

PURPOSE

To compare the 3-year postoperative anterior (ACO) and posterior (PCO) capsule opacification and the level of anterior capsule retraction after implantation of 2 single-piece hydrophobic acrylic intraocular lens (IOL) models.

SETTING

Hospital of St. John of God, Vienna, Austria.

DESIGN

Comparative randomized controlled double-blind clinical trial.

METHODS

Eyes with bilateral cataract were evaluated. Each patient had an Acrysof SA60AT (interrupted optic edge) IOL implanted in 1 eye (Group A) and a Tecnis ZCB00 (continuous optic edge) IOL implanted in the fellow eye (Group B). One and 3 years postoperatively, PCO was evaluated using Evaluation of Posterior Capsule Opacification software and the ACO level and capsule-retraction level were evaluated and graded subjectively.

RESULTS

The study evaluated 100 eyes of 50 patients ranging from 61 to 80 years. Postoperatively, there were no statistically significant differences in PCO between Group A and Group B at 1 year (0.06 ± 0.12 [SD] and 0.07 ± 0.13, respectively; P = 4.35) or 3 years (0.23 ± 0.36 and 0.22 ± 0.32, respectively; P = .66). In Group A and Group B, ACO was present in 18.0% of eyes and 2.7% of eyes, respectively, at 1 year (P = .03) and in 92.0% and 24.0%, respectively, at 3 years (P < .01). Capsule phimosis (18.0% at 1 year; 30.0% at 3 years) and glistenings (66.0% at 1 year; 86.0% at 3 years) were observed in Group A only.

CONCLUSION

Both IOLs had similarly low PCO rates 3 years postoperatively, although more ACO and capsule retraction were observed in eyes with the interrupted optic edge IOL.

Surface modification of intraocular lenses with hyaluronic acid and lysozyme for the prevention of endophthalmitis and posterior capsule opacification

Posterior capsule opacification is one of the complications of cataract surgery caused by the adhesion and reproduction of residual human lens epithelial cells (HLECs) on the posterior capsule.

Hydrated polysaccharide multilayer as an intraocular lens surface coating for biocompatibility improvements

A swollen polysaccharide multilayer was coated on an IOL to inhibit LEC adhesion and proliferation, thus decreasing PCO incidence after implantation.

Lens epithelial cell response to atmospheric pressure plasma modified poly(methylmethacrylate) surfaces

Selective control of cellular response to polymeric biomaterials is an important consideration for many ocular implant applications. In particular, there is often a need to have one surface of an ophthalmic implant capable of promoting cell attachment while the other needs to be resistant to this effect. In this study, an atmospheric pressure dielectric barrier discharge (DBD) has been used to modify the surface region of poly(methyl methacrylate) (PMMA), a well established ocular biomaterial, with the aim of promoting a controlled response to human lens epithelial cells (LEC) cultured thereon. The DBD plasma discharge environment has also been employed to chemically graft a layer of poly(ethylene glycol) methyl ether methacrylate (PEGMA) onto the PMMA and the response to LEC likewise determined. Two different molecular weights of PEGMA, namely 1000 and 2000 MW were used in these experiments. The LEC response to DBD treated polystyrene (PS) samples has also been examined as a positive control and to help to further elucidate the nature of the modified surfaces. The LEC adhered and proliferated readily on the DBD treated PMMA and PS surfaces when compared to the pristine polymer samples which showed little or no cell response. The PMMA and PS surfaces that had been DBD grafted with the PEGMA(1000) layer were found to have some adhered cells. However, on closer inspection, these cells were clearly on the verge of detaching. In the case of the PEGMA(2000) grafted surfaces no cells were observed indicating that the higher molecular weight PEGMA has been able to attain a surface conformation that is capable of resisting cell attachment in vitro.

Effect of delivery of MMP inhibitors from PDMS as a model IOL material on PCO markers

Posterior capsule opacification (PCO) or secondary cataract formation, following intraocular lens implantation, is a significant complication affecting an estimated 28% of cataract patients. Matrix metalloproteinases (MMPs) have been demonstrated to play a role in the formation of anterior subcapsular cataracts and it has been shown that the presence of MMP inhibitors (MMPI) decreases subcapsular cataract formation ex vivo. Since the mechanisms responsible for anterior subcapsular cataract formation and posterior capsule opacification are similar, it is reasonable to suggest that MMP inhibitors may also mitigate PCO. One of the most effective ways of delivering the inhibitors may be from the implanted intraocular lens (IOL) material itself. In the current work, delivery of three different MMP inhibitors from silicone rubber as a model IOL material was examined. Loading methods were developed which allowed continuous release of active MMPI for periods of over 5 months in some cases. Reduced migration rates were observed in human lens epithelial cells in vitro, suggesting that an effect on PCO may be possible. While further studies are necessary to tune the systems to achieve the desired rates of release, this work demonstrates that delivery of MMPI from silicone IOL materials has the potential to decrease the incidence of PCO.

Analysis of surface whitening of extracted hydrophobic acrylic intraocular lenses

PURPOSE

To identify the cause of light scattering on the surface (ie, whitening) of extracted AcrySof intraocular lenses (IOLs).

SETTING

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

METHODS

Dislocated IOLs extracted from 3 patients were stored and the IOL surfaces examined under light microscopy. The effect of whitening on visual function was evaluated by measuring light transmission with a spectrophotometer. To determine the cause of opacification, the IOLs were examined for calcium phosphate deposits using an electron probe X-ray microanalyzer. The IOL surface, including the presence of organic deposits and evidence of hydrolysis, was also examined by Fourier-transform infrared spectrophotometry. The IOLs were then dried, immersed again in physiological saline, and serially examined for changes in opacification.

RESULTS

The optic surfaces of all IOLs had opacification due to whitening. Light transmission in the visible range of 360 to 800 nm was 4% less than that of unused IOLs. The X-ray microanalysis showed no calcium phosphate deposits. Fourier-transform infrared spectrophotometry of the IOL optic material showed no evidence of hydrolysis. Opacification disappeared after the IOLs were dried and then reappeared over time when the IOL was immersed again in physiologic saline.

CONCLUSIONS

The findings strongly suggest that whitening of the hydrophobic acrylic IOL was due to trace water molecules that infiltrate the optic. Within the 3-dimensional network of the polymeric lens material, the molecules are too small to form observable voids but can form water aggregates of sufficient size to scatter visible light, causing opacification (ie, whitening).

Drug delivery systems for the eye

Topical and systemic administration of drugs to the eye is highly inefficient and there is a need for controlled, sustained release, particularly for conditions that affect the posterior segment. Various nonimplantable and implantable drug delivery devices have been developed. Colloidal carriers may allow targeted drug delivery and afford protection to substances that are sensitive to degradation, particularly RNA/DNA-based treatments. Gene therapy and cell transplantation are also starting to emerge as alternatives to conventional pharmacological treatment. There is the potential to use existing ocular devices to deliver drugs. In order to exploit this opportunity, modifications to drugs and devices, along with clarification of the appropriate drug dose, must be undertaken. This review will describe some of the treatment options for ocular disease and barriers to drug delivery, discuss the design of existing drug delivery systems and highlight some of the research into combining drug delivery with existing ocular medical devices.