Preventing Posterior Capsule Opacification Research Articles

GSH Levels Serve As a Biological Redox Switch Regulating Sulforaphane-Induced Cell Fate in Human Lens Cells.

PurposeSulforaphane (SFN) is a therapeutic phytochemical agent for many health conditions. SFN-induced cytotoxicity is shown to have promise in preventing posterior capsule opacification (PCO). In the current study, we aimed to elucidate key processes and mechanisms linking SFN treatment to lens cell death.MethodsThe human lens epithelial cell line FHL124 and central anterior epithelium were used as experimental models. Cell death was assessed by microscopic observation and cell damage/viability assays. Gene or protein levels were assessed by TaqMan RT-PCR or immunoblotting. Mitochondrial networks and DNA damage were assessed by immunofluorescence. Mitochondrial membrane potential, activating transcription factor 6 (ATF6) activity, ratio of reduced glutathione (GSH) to oxidized glutathione (GSSG), and glutathione reductase (GR) activity were measured using different light reporter assays. SFN metabolites were analyzed by LC-MS/MS.ResultsTreatment with N-acetylcysteine (NAC), a reactive oxygen species scavenger, prevented SFN-induced cell death in both models. NAC also significantly protected FHL124 cells from SFN-induced mitochondrial dysfunctions, endoplasmic reticulum stress (ERS), DNA damage and autophagy. SFN significantly depleted GSH, the major antioxidant in the eye, and reduced GR activity, despite doubling its protein levels. The most abundant SFN conjugate detected in lens cells following SFN application was SFN–GSH. The addition of GSH protected lens cells from all SFN-induced cellular events.ConclusionsSFN depletes GSH levels in lens cells through conjugation and inhibition of GR activity. This leads to increased reactive oxygen species and oxidative stress that trigger mitochondrial dysfunction, ERS, autophagy, and DNA damage, leading to cell death. In summary, the work presented provides a mechanistic understanding to support the therapeutic application of SFN for PCO and other disorders.

The Intraocular Lens as a Drug Delivery Device: In Vitro Screening of Pharmacologic Substances for the Prophylaxis of Posterior Capsule Opacification.

Numerous pharmacologic substances have been proposed for preventing posterior capsule opacification (PCO). The following trial was to compare those drugs to find more suitable options. IOL should then be modified by the pharmaceuticals as a drug-delivery device. A systematic literature search was performed to identify published substances. FHL-124 was used to determine cell proliferation and toxicity using a dye reduction test (XTT). Prescreened substances showing a reduction on cell growth without being toxic were soaked into an IOL. Those IOL were tested for their effect on PCO in an anterior-segment model and the human ex vivo capsular bag model. Toxicity on a corneal endothelial cell line (CEC-SV40) was determined. Release kinetics of methotrexate from the IOL was measured. Toxicity testing in both cell lines was done in serum-free conditions. All growth assays were exposed to 10% fetal calf serum (FCS)-supplemented medium. The substances inhibited cell growth at the following EC50: caffeic acid phenethyl ester 1.6 ± 0.9 nM, disulfiram 359 ± 33 nM, methotrexate 98.0 ± 29.7 nM, rapamycin 70.2 ± 14.0 pM, and retinoic acid 1.1 ± 0.12 nM. All but disulfiram showed an effect in the anterior segment model when soaked into an IOL. Long-term inhibitory effects in the human capsular bag model were observed for caffeic acid phenethyl ester and methotrexate IOLs. Only methotrexate and disulfiram did not show any toxicity on endothelial cells. Methotrexate was released constantly from the hydrophilic IOL for 2 weeks. We could identify caffeic acid phenethyl ester and methotrexate in vitro as potential candidates for IOL modification for PCO prophylaxis.

Evaluation of laser capsule polishing for prevention of posterior capsule opacification in a human ex vivo model

To evaluate the efficacy of a laser photolysis (LP) system in preventing posterior capsule opacification (PCO) in a human ex vivo PCO model. Ars Ophthalmica Study Center, Department of Ophthalmology, General Hospital Linz, Medical Faculty of Johannes Kepler University, Linz, Austria, and the Department of Ophthalmology, Ludwig-Maximillians-University, Munich, Germany. Prospective randomized controlled laboratory trial. Open sky extracapsular cataract extraction following implantation of a capsular tension ring (CTR) into the capsular bag was performed in 28 human donor eyes. Donor eyes received LP treatment of the capsular bag fornix and the anterior capsule for 180 or 360 degrees, whereas the contralateral eyes served as a control group. Lens epithelial cell (LEC) growth onto the posterior capsule was determined objectively during 3 months of organ culture incubation. The mean interval until a complete monolayer of LECs on the posterior capsule had formed was 8.2 days ± 1.2 (SD) for control eyes and 9.4 days ± 1.1 for eyes with 180-degree LP treatment (P = .042). Eyes with 360-degree treatment showed no sign of LEC growth or migration onto the posterior capsule during the entire observation period. Transmission light microscopy revealed many residual LECs on the anterior lens capsule of untreated areas, whereas no evidence of remaining LEC in areas treated with LP was found. This study demonstrates complete and sustained PCO prevention by a prototype LP system in a capsular tension ring-based human ex vivo model. Laser capsule polishing has the potential to serve as a successful surgical strategy for PCO prevention. The authors have no proprietary or financial interest in any of the materials or equipment mentioned in this study.

The preparation and the in-vitro pharmacodynamics study of the intracapsular sustained-release preparations for the prevention of posterior capsule opacification

Docetaxel-loaded sustained-release preparation based on 2-Hydroxyethyl methacrylate (HEMA) and Methyl methacrylate (MMA) cross-linked copolymer (P(HEMA-co-MMA)) was prepared to examine the potential use for preventing posterior capsule opacification (PCO). The preparations were prepared by polymerizing the mixture of HEMA, MMA, cross-linking agent (EGDMA), initiator (AIBN) and docetaxel. The influence factors and mechanism of drug release were studied in the experiments. FT-IR, X-RD and SEM methods were used to characterize the polymer (P(HEMA-co-MMA)) and docetaxel-loaded sustained-release preparations. Biocompatibility of P(HEMA-co-MMA) and in-vitro effect of docetaxel-loaded sustained-release preparations were also evaluated. The results showed that docetaxel could release sustainedly from these preparations prepared by cross-linking polymerization. And the release rate could be accelerated by increasing the MMA ratio or EGDMA ratio of the polymer. Release mechanism of docetaxel fitted the Higuchi model well. The results of IR and X-RD showed that only a hydrogen bond was formed between docetaxel and P(HEMA-co-MMA). Docetaxel dispersed in P(HEMA-co-MMA) in amorphous form. The elution test showed that P(HEMA-co-MMA) had good biocompatibility and the in-vitro pharmacodynamics study proved that docetaxel could release stably from the preparations and inhibit HLECs' proliferation. The docetaxel-loaded sustained-release preparations proved to be a promising therapy for preventing PCO. These results also lay a theoretical and experimental foundation for the future.

A Fully Human In Vitro Capsular Bag Model to Permit Intraocular Lens Evaluation

To establish a fully human in vitro culture model with which to test the putative effects of intraocular lens (IOL) designs in preventing posterior capsule opacification (PCO) after cataract surgery. A sham cataract operation was performed to prepare human capsular bags from donor lenses. In one capsular bag of a donor pair, an intraocular lens (PMMA round-edge IOL or acrylic IOL) was implanted while the other capsular bag remained aphakic. Bags were transferred to a Petri dish and secured anterior-face down using entomological pins. Capsular bags were maintained in Eagle's minimum essential medium supplemented with 2% human serum and 10 ng/mL TGF-β to drive growth and matrix contraction. In the absence of an IOL, cells appeared within the central posterior capsule at 4.38 ± 0.26 days, whereas in the presence of a PMMA round-edge IOL or an acrylic IOL they appeared at 8 ± 0.41 days and 11 ± 0.7 days, respectively. Immunocytochemical analysis showed an accumulation of cells at the edge of the acrylic IOL and a less evident accumulation with the PMMA round-edge IOL. Moreover, matrix contraction was more prominent in the absence of an IOL but was still apparent, to a lesser degree, in the presence of a PMMA round-edge IOL. The acrylic IOL greatly suppressed matrix contraction. The authors have developed a fully human in vitro capsular bag system that relates well to clinical observations and permits the testing of novel intraocular lenses.

Genipin suppression of fibrogenic behaviors of the α-TN4 lens epithelial cell line

To determine in a lens epithelial cell line, alpha-TN4, whether genipin, an intestinal metabolite component of the herbal medicine inchin-ko-to, suppresses profibrogenic myofibroblast generation and upregulation of fibrogenic cytokines and to evaluate the potential benefit of the medicine in preventing posterior capsule opacification (PCO). Department of Ophthalmology, Wakayama Medical University, Wakayama, Japan. In this study, alpha-TN4 cell proliferation, migration, and expression of alpha-smooth muscle actin (alpha-SMA), the hallmark of myofibroblast generation, were assayed with a colorimetric assay, scratch wound assay, immunohistochemistry, and Western blot analysis. Gene expression of transforming growth factor-beta1 (TGF-beta1) and connective tissue growth factor (CTGF) was characterized with real-time reverse transcription-polymerase chain reaction. In addition, p38 mitogen-activated protein kinase (p 38 MAPK), extracellular signal-regulated kinase (ERK) limb, and Smad signalings were evaluated by Western blotting and immunohistochemistry. Cytotoxicity of genipin was evaluated using a commercial colorimetric assay kit for nuclear matrix protein 41/7 (NMP41/7) in culture medium. Genipin suppressed cell proliferation and migration in association with inhibition of Smad and p38 MAPK phosphorylation, although ERK signaling was enhanced. Genipin suppressed mRNA expression of TGF-beta1 and CTGF. Cytoplasmic fiber formation declined based on less intense alpha-SMA immunocytochemical staining. However, alpha-SMA protein expression was actually not altered. This negative result suggests that genipin attenuated formation of alpha-SMA-containing cytoskeleton. Treatment of the cells with genipin for 48 hours did not increase the release of NMP41/7 to the medium, indicating this compound is not cytotoxic. Because genipin suppressed alpha-TN4 lens cell fibrogenic behaviors, it may be of therapeutic value in preventing PCO.

Posterior vertical capsulotomy with optic entrapment of the intraocular lens in congenital cataracts—prevention of capsule opacification

To present a modified surgical technique for preventing posterior capsule opacification (PCO) in children with congenital cataracts and to evaluate its long-term efficacy. Department of Ophthalmology, Medical University of Southern Africa, Medunsa, South Africa. Anterior and posterior vertical capsulotomy, with optic entrapment of the intraocular lens (IOL) by maintaining the anterior hyaloid, was performed in 68 cataractous eyes of children aged 2 months to 8 years (mean 3 years, 1 month). The posterior capsule was evaluated for at least 5 years for secondary opacification, IOL position, pigmentary deposits on the IOL optic, and the presence of synechias. Sixty-eight eyes maintained a clear visual axis for 5 to 12 years (mean 9 years, 1 month) postoperatively. No secondary procedure was necessary. In all eyes, the IOL remained well centered and entrapped. Posterior capsulotomy with optic entrapment of the IOL proved to be a safe and efficient surgical procedure for preventing PCO in children with congenital cataracts. Uniting the anterior and posterior capsule in front of the IOL limits the proliferation and migration of Elschnig pearls. An intact anterior hyaloid does not induce capsule opacification in association with optic entrapment; therefore, a vitrectomy is not indicated even in infants under age 5 years. Clear visual axis, centered IOL, and intact vitreous were achieved in this series; this enables a promising long-term prognosis for binocular visual development, especially because surgery was performed early.

Performance of a truncated-edged silicone foldable intraocular lens in Indian eyes

Purpose: To study the role of truncated-edged silicone foldable intraocular lenses (IOLs) in preventing posterior capsule opacification (PCO) in Indian eyes. Setting: Cornea and Anterior Segment Service, L.V. Prasad Eye Institute, Hyderabad, India. Methods: This prospective study evaluated 39 Indian patients (39 eyes) with a mean age of 55.4 years who had uneventful implantation of the CeeOn® Edge 911A IOL (Pharmacia). All IOLs were placed in the bag. Except in 4 patients, the capsulorhexis margin overlapped 360 degrees on the IOL optic periphery. The mean follow-up was 10.9 months (range 6.5 to 13.0 months); 32 patients were followed for 1 year. Results: Intraoperatively, posterior capsule fibrosis was noted in 7 patients. Diffuse haze was noted in the IOL optic in 1 patient. Clinically significant PCO did not occur in any case. One patient had clinically nonsignificant (grade 1) PCO at the 6- and 12-month follow-up visits. Although epithelial pearl accumulation (Soemmering’s ring) was seen beyond the edge of the IOL in the 32 patients followed for 1 year, the epithelial pearls were central only in the patient with grade 1 PCO. Significant cell deposits were noted in 1 patient who had fibrinous uveitis at the 1-week postoperative visit; both resolved by 1 month. All eyes achieved a best corrected visual acuity of 20/30 or better. Conclusions: The CeeOn Edge 911A IOL was well tolerated in Indian eyes, and the posterior capsule remained clear. Larger patient groups with a longer follow-up will provide more useful information.

Intracapsular ring sustained 5-fluorouracil delivery system for the prevention of posterior capsule opacification in rabbits: A histological study

Purpose: To evaluate the efficacy of an intracapsular ring releasing 5-fluorouracil (5-FU) in preventing posterior capsule opacification (PCO) in rabbit eyes. Setting: Center for Research on Ocular Therapeutics and Biodevices, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA, and Chu Morvan, Department d’Ophtalmologie, University of Brest, France. Methods: Seventeen rabbits were divided into 3 groups: Group 1, 6 rabbits (6 eyes), had phacoemulsification only (control group); Group 2, 6 rabbits (6 eyes), had phacoemulsification with implantation of an open-loop hydrogel intracapsular ring; Group 3, 5 rabbits (5 eyes), had phacoemulsification with implantation of a ring with sustained release of 0.25 μg/h of 5-FU for 9 days. All eyes were followed for 8 weeks before enucleation. Capsular bag shrinkage and the position of the intracapsular ring were assessed, and central and peripheral PCO was evaluated for intensity and area by stereomicroscopy from a posterior (Miyake-Apple) view. The residual equatorial lens epithelial cells (LECs) were counted by the same observer in histological sections. Transmission electron microscopy (TEM) of the cornea, capsular bag, and retina was done to evaluate the toxicity of 5-FU. Results: No significant difference was seen in the degree of capsular bag shrinkage in the 3 groups. The intracapsular ring was decentered in 2 eyes (1 each in Groups 2 and 3). There was a statistically significant difference ( P < .05, Student t test) between Group 1 and Groups 2 and 3 in the area and intensity of central PCO. There was no difference between Groups 2 and 3 in the intensity of central PCO. No evidence of 5-FU toxicity to intraocular structures (cornea, capsular bag, and retina) was demonstrated on TEM analysis. Conclusion: Implantation of an intracapsular ring may prevent central PCO after cataract surgery by mechanically blocking LEC migration toward the central visual axis. The potential pharmacological effect of 5-FU in PCO prevention was not demonstrated.

Surgical prevention of posterior capsule opacification: Part 3: Intraocular lens optic barrier effect as a second line of defense

PurposeTo emphasize an important aspect of preventing posterior capsule opacification (PCO), the barrier effect established by the optic of a posterior chamber intraocular lens (PC IOL), and present a new classification regarding capsular bag status after extracapsular cataract extraction, including phacoemulsification. SettingCenter for Research on Ocular Therapeutics and Biodevices, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA. MethodsThis analysis included 150 consecutive eyes obtained postmortem with United States-manufactured PC IOLs including (1) poly(methyl methacrylate), (2) silicone, and (3) hydrophobic acrylic designs that were accessioned in the Center from September 1995 to January 1, 1998. Gross photographs from behind (Miyake–Apple views) were taken and serial histologic sections prepared. ResultsMicroscopic analysis of the 150 eyes showed that the morphologic appearance of the capsular bag could be grouped into 2 categories: (1) those with little or no evidence of retained cortical material and cells, and (2) those with retained cortical material and cells in which a Soemmering’s ring formed. With the latter, when a distinct barricade to cellular migration created by the IOL optic was noted, 2 discrete configurations occurred, depending on the different geometries of the optic components. With a classic biconvex optic with a curved and tapered edge, in many instances some ingrowth of cells proceeded posteriorly around the edge of the IOL optic in the direction of the central axis. With a lens optic that had a squared, truncated, and relatively thick edge, there was often abrupt termination of cells at the peripheral edge of the optic. The posterior capsule subtending the entire optic zone was therefore relatively or totally cell free. ConclusionsThe barrier effect of the IOL optic appears to be of critical importance in retarding ingrowth of cells, functioning as a second line of defense when cortical cleanup is incomplete. Analysis of PC IOLs obtained postmortem showed that a square, truncated optic edge seemed to provide the maximum impediment to cell growth behind the IOL optic.

Primary posterior capsulorhexis without anterior vitrectomy in pediatric cataract surgery: Longer term outcome

Purpose To assess the effectiveness of primary posterior capsulorhexis without anterior vitrectomy in preventing posterior capsule opacification (PCO) in pediatric cataract surgery. Setting Children’s Hospital, Dublin, Republic of Ireland. Methods The study comprised 32 eyes of 22 pediatric patients who had cataract extraction between 1994 and 1998. Extracapsular cataract extraction was performed using radiofrequency diathermy capsulorhexis to the anterior and posterior capsules without an anterior vitrectomy. Posterior chamber intraocular lens implantation was performed in 20 eyes. There were 23 congenital, 6 developmental, and 3 traumatic cataracts. Results Patient age ranged from 1 month to 12 years. Mean follow-up was 19 months (range 6 to 50 months). Twenty-seven of 32 eyes (84.4%) had a clear visual axis at last follow-up. Five eyes required a neodymium:YAG capsulotomy, which was performed a mean of 5 months postoperatively (range 1 to 9 months). The incidence of PCO requiring capsulotomy was 15.6%. Conclusion Primary posterior capsulorhexis without anterior vitrectomy was safe and effective, with a low reopacification rate. Long-term follow-up of this patient cohort is necessary.