Posterior Capsule Opacification After Phacoemulsification: Annual Review

Photo-controllable drug releasing bulk polyacrylic intraocular lens material for safer posterior capsular opacification prevention

Posterior capsular opacification (PCO) is the most common complication that occurs after intraocular lens (IOL) implantation in cataract therapy. In recent years, IOLs have been developed as drug delivery platforms, but concerns over the safety of uncontrolled proliferative drug release have arisen. Therefore, a controlled drug release strategy is needed for safer PCO prevention. In this study, a new monomer contained coumarin group was introduced in material preparation, and poly(ethylene glycol phenyl ether methacrylate-co-2-(2-ethoxyethoxy) ethyl acrylate-co-7-(2-methacryloyloxyethoxy)-4-methylcoumarin) (PEEC) acrylic IOL materials were synthesized. The antiproliferative drug 5-fluorouracil (5-FU) could be chemically grafted to the PEEC IOL materials easily via a light induced [2 + 2] cycloaddition reaction with the coumarin group, getting drug-loaded IOL (PEEC@5-FU IOL). The PEEC@5-FU IOL exhibited excellent optical and mechanical properties and biocompatibility. More importantly, the loaded 5-FU could be easily controlled from release by light irradiation via photo-dissociation of the cyclobutane ring that was obtained by the [2 + 2] cycloaddition reaction of 5-FU and coumarin. The in vitro and in vivo experiments demonstrated that such photo-controllable drug release IOL could effectively prevent PCO after implantation in a safe way.

Mild Photothermal Therapy Prevents Posterior Capsule Opacification through Cytoskeletal Remodeling

Cataract is the first leading cause of blindness in the world and posterior capsule opacification (PCO) is the most common long-term complication after surgery. The primary pathogenic processes contributing to PCO are the proliferation and migration of residual lens epithelial cells (LECs). This study aimed to explore the mild photothermal effect on LECs. Interestingly, this work finds that the mild photothermal effect significantly inhibited the proliferation and migration of LECs. The live cell fluorescence imaging reveals that the remodeling of the actin cytoskeleton and cell morphology attributed to the inhibition effect. Further mechanistic studies at molecular level suggest that the mild photothermal effect can regulate the phosphorylation of ERM, YAP, and Cofilin and thereby affect the proliferation and migration of LECs. In order to explore the potential clinical application of mild photothermal therapy for PCO prevention, PDA/PVA gel rings with photothermal effect is prepared by the repeated freeze-thaw method and conducted experiments in vivo, which achieved favorable PCO prevention effect. Overall, this study shows that the mild photothermal effect can regulate the proliferation and migration of LECs through cytoskeletal remodeling and the results of experiments in vivo demonstrate that mild photothermal effect is a promising approach for PCO prevention.

Glutaredoxin 2 protects lens epithelial cells from epithelial-mesenchymal transition by suppressing mitochondrial oxidative stress-related upregulation of integrin-linked kinase

Glutaredoxin 2 (Grx2), a mitochondrial glutathione-dependent oxidoreductase, is crucial for maintaining redox homeostasis and cellular functions in the lens. The oxidative stress-induced epithelial-mesenchymal transition (EMT) of lens epithelial cells (LECs) is related to posterior capsule opacification. In this study, we investigated the effects of Grx2 on oxidative stress-induced EMT in LECs during posterior capsule opacification. We found that Grx2 expression was substantially decreased during the EMT of LECs and in a mouse model of cataract surgery. Deletion of Grx2 aggravated the generation of reactive oxygen species, including those that are mitochondria-derived, and promoted the proliferation and EMT of the LECs. This was reversed by Grx2 overexpression. In vivo, proteomic liquid chromatography-mass spectrometry analysis showed that integrin-linked kinase (ILK) was significantly upregulated in the lens posterior capsule of a Grx2 knockout (KO) mouse model. Compared with that of the wild-type group, the expression of ILK and EMT markers was increased in the Grx2 KO group which was reversed in the Grx2 knock-in group. Inhibition of ILK partially blocked Grx2 knockdown-induced EMT and prevented the increased phosphorylation of Akt and GSK-3β and the nuclear translocation of β-catenin in the Grx2 KO group. Finally, inhibition of the Wnt/β-catenin pathway partially blocked the Grx2 knockdown-induced EMT. In conclusion, we demonstrated that Grx2 protects LECs from oxidative stress-related EMT by regulating the ILK/Akt/GSK-3β axis.

Effect of Nd:YAG laser capsulotomy on graft endothelium after penetrating keratoplasty

BACKGROUND

To investigate the safety of Nd:YAG laser capsulotomy in eyes with Penetrating Keratoplasty (PK) and its impact on corneal endothelium as well as graft survival.

METHODS

Thirty patients who underwent Nd: YAG laser capsulotomy after PK and 30 pseudophakic control eyes were included in this prospective study. Endothelial cell density (ECD), hexagonality (HEX), coefficient of variation (CV), central corneal thickness (CCT), and the change of these values during follow-up measured at the 1st hour, first week, and first month after the laser and the data were compared between groups.

RESULTS

The mean time passed between the PK procedure and the subsequent YAG laser procedure was i.e. of YAG laser after PK was 30.5 ± 15.2 months (range 6 to 57 months). Baseline ECD was 1648.2 ± 669.77 cells/mm² in the PK group and 2008.27 ± 347.42 cells/mm² in the control group. In the first month, ECD was 1545.2 ± 639.35 cells/mm² in the PK group and 1979 ± 350.95 in the control group. The loss was significantly higher in PK group (-103 ± 153.67 cells/mm²) (6.25%) compare to the control group (-28.73 ± 82.31 cells/mm²) (1.44%) (p = 0.024). A significant increase in CV was observed in the PK group, and not in the control group (p = 0.008, p = 0.255, respectively). There were no significant changes in HEX and CCT values in either group.

CONCLUSION

Nd:YAG laser provides a significant increase in visual acuity in first month in patients with PK with no significant harmful effect on graft transparency. Endothelial cell density measurements during follow-up will be beneficial.

Glutaredoxin 1 protects lens epithelial cells from epithelial-mesenchymal transition by preventing casein kinase 1α S-glutathionylation during posterior capsular opacification

Oxidative stress drives protein S-glutathionylation, which regulates the structure and function of target proteins and is implicated in the pathogenesis of many diseases. Glutaredoxin 1 (Grx1), a cytoplasmic deglutathionylating enzyme, maintains a reducing environment within the cell under various conditions by reversing S-glutathionylation. Grx1 performs a wide range of antioxidant activities in the lens and prevents protein-thiol mixed disulfide accumulation, reducing protein-protein aggregation, insolubilization, and apoptosis of lens epithelial cells. Oxidative stress is related to epithelial-mesenchymal transition (EMT) during posterior capsular opacification (PCO). However, whether Grx1-regulated protein S-glutathionylation plays an essential role in PCO remains unclear. In this study, we revealed that Grx1 expression was decreased in mice following cataract surgery. Furthermore, the absence of Grx1 elevated oxidative stress and protein S-glutathionylation and aggravated EMT in both in vitro and in vivo models. Concurrently, these results could be reversed by Grx1 overexpression. Notably, liquid chromatography-tandem mass spectrometry results showed that casein kinase 1α (CK1α) was susceptible to S-glutathionylation under oxidative stress, and CK1α S-glutathionylation (CK1α-SSG) was mediated at Cys249. The absence of Grx1 upregulated CK1α-SSG, subsequently decreasing the CK1α-induced phosphorylation of β-catenin at Ser45. The consequential downregulation of degradative β-catenin and upregulation of its nuclear translocation activated the Wnt/β-catenin signaling pathway and aggravated EMT. In conclusion, the downregulated expression of Grx1 in mice following cataract surgery aggravated EMT by upregulating the extent of CK1α-SSG. To the best of our knowledge, our study is the first to report how S-glutathionylation regulates CK1α activity under oxidative stress.

FGF-2 Differentially Regulates Lens Epithelial Cell Behaviour during TGF-β-Induced EMT

Fibroblast growth factor (FGF) and transforming growth factor-beta (TGF-β) can regulate and/or dysregulate lens epithelial cell (LEC) behaviour, including proliferation, fibre differentiation, and epithelial–mesenchymal transition (EMT). Earlier studies have investigated the crosstalk between FGF and TGF-β in dictating lens cell fate, that appears to be dose dependent. Here, we tested the hypothesis that a fibre-differentiating dose of FGF differentially regulates the behaviour of lens epithelial cells undergoing TGF-β-induced EMT. Postnatal 21-day-old rat lens epithelial explants were treated with a fibre-differentiating dose of FGF-2 (200 ng/mL) and/or TGF-β2 (50 pg/mL) over a 7-day culture period. We compared central LECs (CLECs) and peripheral LECs (PLECs) using immunolabelling for changes in markers for EMT (α-SMA), lens fibre differentiation (β-crystallin), epithelial cell adhesion (β-catenin), and the cytoskeleton (alpha-tropomyosin), as well as Smad2/3- and MAPK/ERK1/2-signalling. Lens epithelial explants cotreated with FGF-2 and TGF-β2 exhibited a differential response, with CLECs undergoing EMT while PLECs favoured more of a lens fibre differentiation response, compared to the TGF-β-only-treated explants where all cells in the explants underwent EMT. The CLECs cotreated with FGF and TGF-β immunolabelled for α-SMA, with minimal β-crystallin, whereas the PLECs demonstrated strong β-crystallin reactivity and little α-SMA. Interestingly, compared to the TGF-β-only-treated explants, α-SMA was significantly decreased in the CLECs cotreated with FGF/TGF-β. Smad-dependent and independent signalling was increased in the FGF-2/TGF-β2 co-treated CLECs, that had a heightened number of cells with nuclear localisation of Smad2/3 compared to the PLECs, that in contrast had more pronounced ERK1/2-signalling over Smad2/3 activation. The current study has confirmed that FGF-2 is influential in differentially regulating the behaviour of LECs during TGF-β-induced EMT, leading to a heterogenous cell population, typical of that observed in the development of post-surgical, posterior capsular opacification (PCO). This highlights the cooperative relationship between FGF and TGF-β leading to lens pathology, providing a different perspective when considering preventative measures for controlling PCO.

Pediatric cataract surgery: Rate of secondary visual axis opacification depending on intraocular lens type

PURPOSE

To assess the time course of secondary visual axis opacification (VAO) that led to additional surgery after primary intraocular lens (IOL) implantation in children and to describe further surgical outcomes. Comparison of different lens types.

DESIGN

Single center, retrospective analysis of children aged 1-14 years who underwent cataract surgery with primary IOL implantation. The surgical technique was either in-bag IOL placement with primary posterior capsulotomy and anterior vitrectomy or bag-in-lens IOL placement. We excluded eyes with visually significant ocular comorbidities.

SUBJECTS

Total of 135 eyes of 95 children. Of these, 64 had received an acrylic three-piece IOL, 51 an acrylic single-piece IOL, and 20 an acrylic single-piece bag-in-lens IOL. The median ages at surgery were 53 months (IQR 35-75), 52 months (27-65), and 60 months (40-84) in the 3-piece, 1-piece, and bag-in-lens group, respectively.

METHODS

Analysis of medical records. We used the Kaplan-Meier method and a cox proportional hazards model with pre-defined adjustments for age at surgery, year of surgery, and socioeconomic deprivation (GISD score by postal code) to analyze VAO-free survival by lens type. Patients were invited to attend a clinical visit to achieve longer follow-ups.

MAIN OUTCOME MEASURES

The rate of survival without VAO that required clearing of the visual axis after cataract surgery with primary IOL implantation. Any other surgical complications.

RESULTS

The overall median follow-up was 19 months (IQR 3-58). There were 13 cases of VAO, occurring at a median of 10 months (IQR 10-12) after surgery. Of these, 1 eye had a 3-piece in-bag IOL, 10 eyes had 1-piece in-bag IOLs, and 2 eyes had bag-in-lens IOLs. The adjusted hazard ratio was 32.8 (95% CI: 3.3-327, p=0.003) for 1-piece acrylic IOLs and 19.6 (1.22-316, p=0.036) for bag-in-lens IOLs, compared to 3-piece acrylic in-bag IOLs. Two eyes with bag-in-lens surgery (10%) had an iris capture. There was one case of endophthalmitis. We found no cases of postoperative retinal detachment or new glaucoma.

CONCLUSIONS

Children with secondary visual axis opacification that required a procedure to clear the visual axis generally presented within fifteen months. Opacification rates were lowest when a 3-piece acrylic IOL was used.

Essential function of adaptor protein Nck1 in platelet-derived growth factor receptor signaling in human lens epithelial cells

Binding of platelet-derived growth factor-BB (PDGF-BB) to its cognate receptor (PDGFR) promotes lens epithelial cell (LEC) proliferation and migration. After cataract surgery, these LEC behaviors have been proposed as an influential cause of posterior capsule opacification (PCO). Stimulated PDFGR undergoes dimerization and tyrosine phosphorylation providing docking sites for a SH2-domain-containing noncatalytic region of tyrosine kinase (Nck). Nck is an adaptor protein acting as a linker of the proximal and downstream signaling events. However, the functions of Nck1 protein in LEC have not been investigated so far. We reported here a crucial role of Nck1 protein in regulating PDGFR-mediated LEC activation using LEC with a silenced expression of Nck1 protein. The knockdown of Nck1 suppressed PDGF-BB-stimulated LEC proliferation and migration and disrupted the cell cycle progression especially G1/S transition. LEC lacking Nck1 protein failed to exhibit actin polymerization and membrane protrusions. The downregulation of Nck1 protein in LEC impaired PDGFR‐induced phosphorylation of intracellular signaling proteins, including Erk1/2, Akt, CREB and ATF1, which resulted in inhibition of LEC responses. Therefore, these data suggest that the loss of Nck1 expression may disturb LEC activation and Nck1 may potentially be a drug target to prevent PCO and lens-related disease.

Drug-eluting intraocular lens with sustained bromfenac release for conquering posterior capsular opacification

Cataract is the leading cause of visual impairment, and posterior capsular opacification (PCO) is the most common long-term complication of modern cataract surgery, which can cause severe visual impairment after surgery. The proliferation, migration, and epithelial-mesenchymal transition (EMT) of residual lens epithelial cells (LECs) stimulated by growth factors and cytokines, are the key pathological mechanisms involved in the development of PCO. This study demonstrated that non-steroidal anti-inflammatory drug (NSAID), bromfenac, was capable of effectively inhibiting cell migration, overexpression of EMT markers, such as fibronectin (FN), matrix metalloproteinase 2 (MMP2), α-smooth muscle actin (α-SMA), and transcription factor Snail, and extracellular signal-regulated kinase (ERK)/glycogen synthase kinase-3β (GSK-3β) signaling induced by transforming growth factor-β2 (TGF-β2) in vitro. The inhibitory effect of bromfenac on TGF-β2-induced EMT was also verified on a primary lens epithelial cell model using human anterior capsules. Furthermore, based on ultrasonic spray technology, we developed a drug-eluting intraocular lens (IOL) using poly (lactic-co-glycolic acid) (PLGA) with sustained bromfenac release ability for the prevention of PCO development. In the rabbit models of cataract surgery, bromfenac-eluting IOL exhibited remarkable PCO prevention and inflammation suppression effects with excellent biocompatibility. In conclusion, bromfenac can inhibit TGF-β2-induced cell migration and the EMT of LECs via ERK/GSK-3β/Snail signaling. The present study offers a novel approach for preventing PCO through PLGA-based drug sustained-release IOLs.

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Bromfenac inhibited TGF-β2-induced migration and EMT of LECs through ERK/GSK-3β/Snail signaling.

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Drug-eluting IOLs with sustained bromfenac release were developed based on ultrasonic spray technology.

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Bromfenac-eluting IOLs exhibited remarkable PCO prevention and inflammation suppression effects in vivo.

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Bromfenac-eluting IOLs hold great potential for clinical application of PCO prevention.

Effect of time and temperature-dependent changes of IOL material properties on IOL: Lens capsule interactions

Posterior Capsule Opacification (PCO) is the most common complication associated with Intraocular Lens (IOL) implantation. Based on the assumption that the interactions between an IOL and the lens capsule (LC) may influence the extent of PCO formation, a new in vitro model was developed to quantify the adhesion force of an IOL to simulated LC using a custom-designed micro-force tester. Using this system, we examined the influence of temperature (room temperature vs. body temperature) and incubation time (0 vs. 24 h) on the adhesion force between IOLs and LCs. The results show that, in line with clinical observations of PCO incidence, the adhesion force increased at body temperature and with increase in incubation time in the following order, Acrylic foldable IOLs > Silicone IOLs > PMMA IOLs. By examining the changes of surface properties as a function of temperature and incubation time, we found that acrylic foldable IOLs showed the largest increase in their hydrophilicity and reported the lowest surface roughness in comparison to other IOL groups. Coincidentally, using a newly established macromolecular dye imaging system to simulate cell migration between IOLs and LC, we observed that the amount of macromolecular dye infiltration between IOLs and LCs was in the following order: PMMA IOLs > Silicone IOLs > Acrylic foldable IOLs. These results support a new potential mechanism that body temperature, incubation time, surface hydrophilicity and smoothness of IOLs greatly contribute to their tight binding to LCs and such tight binding may lead to reduced IOL: LC space, cell infiltration, and thus PCO formation.

An in vitro system to investigate IOL: Lens capsule interaction

Posterior capsule opacification (PCO) is the most common complication associated with intraocular lens (IOL) implantation. Unfortunately, current in vitro models cannot be used to assess the potential of PCO due to their failure to simulate the posterior curvature of the lens capsule (LC) and IOL, a factor known to affect PCO pathogenesis in clinic. To overcome such a challenge, a new system to study IOL: LC interaction and potentially predict PCO was developed in this effort. It is believed that the interactions between an IOL and the lens capsule may influence the extent of PCO formation. Specifically, strong adhesion force between an IOL and the LC may impede lens epithelial cell migration and proliferation and thus reduce PCO formation. To assess the adhesion force between an IOL and LC, a new in vitro model was established with simulated LC and a custom-designed micro-force tester. A method to fabricate simulated LCs was developed by imprinting IOLs onto molten gelatin to create simulated three dimensional (3D) LCs with curvature resembling the bag-like structure that collapses on the IOL post implantation. By pushing the LC mold vertically downward, while measuring the change in position of the bending bar with respect to its start position, the adhesion force between the IOLs and LCs was measured. An in vitro system that can measure the adhesion force reproducibly between an IOL and LC with a resolution of ~1 μN was established in this study. During system optimization, the 10% high molecular weight gelatin produced the best LC with the highest IOL: LC adhesion force with all test lenses that were fabricated from acrylic foldable, polymethylmethacrylate (PMMA) and silicone materials. Test IOLs exerted different adhesion force with the 3D simulated LCs in the following sequence: acrylic foldable IOL > silicone IOL > PMMA IOL. These results are in good agreement with the clinical observations associated with PCO performance of IOLs made of the same materials. This novel in vitro system can provide valuable insight on the IOL: LC interplay and its relationship to clinical PCO outcomes.

Fibronectin has multifunctional roles in posterior capsular opacification (PCO)

Fibrotic posterior capsular opacification (PCO), one of the major complications of cataract surgery, occurs when lens epithelial cells (LCs) left behind post cataract surgery (PCS) undergo epithelial to mesenchymal transition, migrate into the optical axis and produce opaque scar tissue. LCs left behind PCS robustly produce fibronectin, although its roles in fibrotic PCO are not known. In order to determine the function of fibronectin in PCO pathogenesis, we created mice lacking the fibronectin gene (FN conditional knock out -FNcKO) from the lens. While animals from this line have normal lenses, upon lens fiber cell removal which models cataract surgery, FNcKO LCs exhibit a greatly attenuated fibrotic response from 3 days PCS onward as assessed by a reduction in surgery-induced cell proliferation, and fibrotic extracellular matrix (ECM) production and deposition. This is correlated with less upregulation of Transforming Growth Factor β (TGFβ) and integrin signaling in FNcKO LCs PCS concomitant with sustained Bone Morphogenetic Protein (BMP) signaling and elevation of the epithelial cell marker E cadherin. Although the initial fibrotic response of FNcKO LCs was qualitatively normal at 48 h PCS as measured by the upregulation of fibrotic marker protein αSMA, RNA sequencing revealed that the fibrotic response was already quantitatively attenuated at this time, as measured by the upregulation of mRNAs encoding molecules that control, and are controlled by, TGFβ signaling, including many known markers of fibrosis. Most notably, gremlin-1, a known regulator of TGFβ superfamily signaling, was upregulated sharply in WT LCs PCS, while this response was attenuated in FNcKO LCs. As exogenous administration of either active TGFβ1 or gremlin-1 to FNcKO lens capsular bags rescued the attenuated fibrotic response of fibronectin null LCs PCS including the loss of SMAD2/3 phosphorylation, this suggests that fibronectin plays multifunctional roles in fibrotic PCO development.

Cataract surgeon viewpoints on the need for novel preventative anti-inflammatory and anti-posterior capsular opacification therapies

Purpose: To determine cataract surgeon viewpoints on the efficacy of available therapies/preventatives for two common sequelae of cataract surgery: inflammation and posterior capsular opacification (PCO). Methods: Cataract surgeons practicing worldwide specializing in adult, pediatric and veterinary patients were interviewed between March and August 2018. Results: Ocular inflammation following cataract surgery is treated by either corticosteroids and/or nonsteroidal anti-inflammatories (NSAIDs). Adult and pediatric cataract surgeons are satisfied with current treatments whereas this inflammation is still considered a problem by some in veterinary practice due to its slow resolution. Yttrium-aluminum-garnet (YAG) laser therapy is the PCO treatment of choice for adult cataract surgeons and they are generally pleased with its outcome. However, pediatric cataract surgeons find YAG problematic, especially in patients under 6 years of age, and invasive surgery is often needed to correct PCO/visual axis opacification (VAO). Veterinary ophthalmologists report that YAG is not effective for PCO in animals, especially dogs, due to the density of the fibrotic plaques; 86% of adult and 100% of veterinary and pediatric cataract surgeons surveyed agree that effective anti-PCO therapeutics would improve clinical care. Conclusions: Surgeons treating human patients are pleased with the available treatments for ocular inflammation following cataract surgery, although some veterinary ophthalmologists disagree. The surgeons surveyed agree that PCO/VAO remains an unsolved problem in pediatric and veterinary cataract surgery while the long-term outcome of adult cataract surgery could be improved by additional attention to this issue.

5 year incidence of YAG capsulotomy and PCO after cataract surgery with single-piece monofocal intraocular lenses: a real-world evidence study of 20,763 eyes

OBJECTIVES

To evaluate the 3- and 5-year incidence of posterior capsule opacification (PCO) and neodymium-doped yttrium aluminium garnet (Nd:YAG) capsulotomy in patients following cataract surgery, comparing results for different single-piece acrylic hydrophilic and hydrophobic monofocal intraocular lens (IOL) models and other patient factors.

PATIENTS AND METHODS

Electronic medical record data collected from seven United Kingdom (UK) National Health Service (NHS) ophthalmology clinics for routine, age-related (≥65 years) cataract surgeries that implanted single-piece acrylic monofocal IOLs during 2010-2013 were used to calculate 3- and 5-year incidence of Nd:YAG and PCO. IOL models of Alcon Acrysof, AMO Tecnis, Bausch & Lomb (B & L) Akreos, LenStec Softec, and Rayner Flex were analyzed. Pairwise comparisons were conducted between AcrySof IOLs and other IOLs using Bonferroni adjustment for multiplicity. Multivariate analyses were conducted adjusting for known confounders.

RESULTS

The incidence of Nd:YAG capsulotomy ranged between 2.4-12.6% at 3 years and 5.8-19.3% at 5 years post-cataract surgery. Similarly, the incidence of PCO ranged between 4.7-18.6% at 3 years and 7.1-22.6% at 5 years. When comparing all of the single-piece IOLs, AcrySof demonstrated the lowest incidence rates for both PCO and Nd:YAG (P < 0.001 for each comparison). From adjusted logistic regression analysis, AcrySof were associated with lower 3- and 5-year odds of Nd:YAG and PCO incidence.

CONCLUSIONS

Following cataract surgery with single-piece monofocal IOLs different incidence rates of PCO were observed with different IOLs. AcrySof IOLs were associated with significantly lower incidence of PCO requiring Nd:YAG treatment over periods of 3 and 5 years.

Fibronectin regulates growth factor signaling and cell differentiation in primary lens cells

Lens epithelial cells are bound to the lens extracellular matrix capsule, of which laminin is a major component. After cataract surgery, surviving lens epithelial cells are exposed to increased levels of fibronectin, and so we addressed whether fibronectin influences lens cell fate, using DCDML cells as a serum-free primary lens epithelial cell culture system. We found that culturing DCDMLs with plasma-derived fibronectin upregulated canonical TGFβ signaling relative to cells plated on laminin. Fibronectin-exposed cultures also showed increased TGFβ signaling-dependent differentiation into the two cell types responsible for posterior capsule opacification after cataract surgery, namely myofibroblasts and lens fiber cells. Increased TGFβ activity could be identified in the conditioned medium recovered from cells grown on fibronectin. Other experiments showed that plating DCDMLs on fibronectin overcomes the need for BMP in fibroblast growth factor (FGF)-induced lens fiber cell differentiation, a requirement that is restored when endogenous TGFβ signaling is inhibited. These results demonstrate how the TGFβ-fibronectin axis can profoundly affect lens cell fate. This axis represents a novel target for prevention of late-onset posterior capsule opacification, a common but currently intractable complication of cataract surgery.

Resident-performed neodymium:YAG laser posterior capsulotomy

OBJECTIVE

To investigate the outcomes of resident-performed Nd:YAG laser posterior capsulotomy.

DESIGN

Combined retrospective and prospective study.

PARTICIPANTS

Patients (N = 301) who underwent Nd:YAG capsulotomy by ophthalmology residents at Rassoul Akram Hospital, Tehran, Iran.

METHODS

Assessment of visual outcomes and complications and the results of second- and third-year residents.

RESULTS

In the retrospective arm, 131 eyes of 129 patients were enrolled. Mean best-corrected visual acuity (BCVA) improved significantly from 1.15 ± 0.26 to 0.54 ± 0.39 logMAR (p < 0.001). Mean intraocular pressure (IOP) before capsulotomy and at the final visit was 13.1 ± 2.34 mm Hg and 13.6 ± 2.17 mm Hg, respectively (P = 0.30). Retinal detachment occurred in 2 eyes (1.5%). No case of intraocular lens decentration or endophthalmitis was detected. In the prospective arm on 173 eyes of 172 patients, mean pre-YAG BCVA was 1.14 ± 0.25 logMAR and increased to 0.51 ± 0.37 logMAR after surgery (p < 0.001). There was no significant difference between pre-laser IOP measurements compared with the 1-month IOP measurements (P = 0.32). The postoperative changes in mean BCVA and IOP between the second- and third-year residents were not significant; however, the applied laser power, the number of laser spots, rate of incomplete capsulotomies, and the amount of total and central laser-induced IOL pits were significantly higher among the second-year residents.

CONCLUSIONS

Resident-performed capsulotomy appears to be effective with a low complication profile. Despite the lower levels of surgical skills, second-year residents could achieve good visual outcomes. The laser parameters and IOL-related complications improved with increasing surgical experience.

Dual function of TGFβ in lens epithelial cell fate: implications for secondary cataract

The most common vision-disrupting complication of cataract surgery is posterior capsule opacification (PCO; secondary cataract). PCO is caused by residual lens cells undergoing one of two very different cell fates: either transdifferentiating into myofibroblasts or maturing into lens fiber cells. Although TGFβ has been strongly implicated in lens cell fibrosis, the factors responsible for the latter process have not been identified. We show here for the first time that TGFβ can induce purified primary lens epithelial cells within the same culture to undergo differentiation into either lens fiber cells or myofibroblasts. Marker analysis confirmed that the two cell phenotypes were mutually exclusive. Blocking the p38 kinase pathway, either with direct inhibitors of the p38 MAP kinase or a small-molecule therapeutic that also inhibits the activation of p38, prevented TGFβ from inducing epithelial-myofibroblast transition and cell migration but did not prevent fiber cell differentiation. Rapamycin had the converse effect, linking MTOR signaling to induction of fiber cell differentiation by TGFβ. In addition to providing novel potential therapeutic strategies for PCO, our findings extend the so-called TGFβ paradox, in which TGFβ can induce two disparate cell fates, to a new epithelial disease state.