Posterior capsule opacification

Incorrectly Focused Neodymium:Yttrium-Aluminum-Garnet (Nd:YAG) Laser Beam Leads to Massive Destructive Effects in Small-Aperture (Pinhole) Intraocular Lenses

INTRODUCTION

Pinhole intraocular lenses (IOLs) were developed to improve reading by compensating for loss of accommodative function. The IC-8® Apthera™ is a small-aperture presbyopia-correcting IOL that combines the proven principle of small-aperture optics with an aspheric monofocal lens to deliver a continuous range of vision for patients with cataracts from distance to near vision. Posterior capsule opacification is the most common sequela after cataract surgery. It is effectively treated by laser capsulotomy. However, if the laser beam is incorrectly focused, the IOL can be permanently damaged (pits/shots).

METHODS

In this experimental study, yttrium-aluminum-garnet (YAG) pits were purposefully created. Defects were analyzed and compared between the periphery of the ring in the clear area of the hydrophobic acrylic lens and at the carbon black (CB)-polyvinylidene fluoride (PVDF) filtering component (FilterRing™) of the pinhole lens. All defects were made using identical settings/energy levels (2.6 mJ). The damage induced to the IC-8® Apthera™ IOL was examined by low-magnification images, light microscopy, scanning electron microscopy, and micro-computed tomography (micro-CT).

RESULTS

YAG defects in the carbon black filter ring were much more severe than those in the clear zone due to the high absorption of the carbon black. Massive defects and destruction of the lens with tearing out of fragments and particles were observed. The missing volume calculated from the micro-CT reconstruction was 0.266 mm3, which is 1.6% of the entire IOL volume, or more than 1000 times the volume damaged in the largest shot in the periphery.

CONCLUSION

Based on the results, we highly recommend using the lowest possible energy levels, posterior offset setting, and circular pattern for maximum safety when performing laser capsulotomy with pinhole implants. Care should be taken to avoid creating irreversible iatrogenic defects that may affect overall quality. The safest area for performing capsulotomy seems to be the periphery of the ring segment. Video available for this article.

TGFβ overcomes FGF-induced transinhibition of EGFR in lens cells to enable fibrotic secondary cataract

To cause vision-disrupting fibrotic secondary cataract (PCO), lens epithelial cells that survive cataract surgery must migrate to the posterior of the lens capsule and differentiate into myofibroblasts. During this process, the cells become exposed to the FGF that diffuses out of the vitreous body. In normal development, such relatively high levels of FGF induce lens epithelial cells to differentiate into lens fiber cells. It has been a mystery as to how lens cells could instead undergo a mutually exclusive cell fate, namely epithelial to myofibroblast transition, in the FGF-rich environment of the posterior capsule. We and others have reported that the ability of TGFβ to induce lens cell fibrosis requires the activity of endogenous ErbBs. We show here that lens fiber-promoting levels of FGF induce desensitization of ErbB1 (EGFR) that involves its phosphorylation on threonine 669 mediated by both ERK and p38 activity. Transinhibition of ErbB1 by FGF is overcome by a time-dependent increase in ErbB1 levels induced by TGFβ, the activation of which is increased after cataract surgery. Our studies provide a rationale for why TGFβ upregulates ErbB1 in lens cells and further support the receptor as a therapeutic target for PCO.

Refractive Changes Following Premature Posterior Capsulotomy Using Neodymium:Yttrium–Aluminum–Garnet Laser

We aimed to determine the timing of neodymium:yttrium–aluminum–garnet (Nd:YAG) laser capsulotomy on corrected-distance visual acuity (CDVA), intraocular pressure (IOP), and spherical equivalent (SE) in patients with posterior capsular opacification (PCO). There were 59 patients with unilateral PCO and a history of Nd:YAG laser capsulotomy enrolled and further divided into the early Nd:YAG group (timing < 12 months, n = 25) and late Nd:YAG group (timing > 12 months, n = 34) depending on the elapsed months from phacoemulsification to Nd:YAG laser capsulotomy. The primary outcomes were CDVA, IOP, and SE before (immediately before Nd:YAG laser capsulotomy) and after (weeks one and four after the laser treatment). The independent t test was applied to analyze the difference in CDVA, IOP, and SE between the two groups, while the generalized estimating equation with Bonferroni adjustment was conducted to evaluate the effect of all the parameters on the change in SE with adjusted odds ratio (aOR) and 95% confidence interval (CI). The CDVA showed significant improvement in both the early Nd:YAG group (p = 0.005) and the late Nd:YAG group (p = 0.001), and hyperopic change occurred in both the early Nd:YAG group (p = 0.003) and the late Nd:YAG group (p = 0.017). The early Nd:YAG group revealed more significant hyperopic change compared with the late Nd:YAG group four weeks after Nd:YAG treatment (p < 0.001), which was still significant after multivariable analysis (aOR: 0.899, 95% CI: 0.868–0.930, p = 0.011). In addition, a deeper ACD (aOR: 0.764, 95% CI: 0.671–0.869, p = 0.019) was significantly correlated with hyperopic change. In conclusion, Nd:YAG laser capsulotomy performed within one year after cataract surgery may lead to significant hyperopic change, in which the ACD alteration affects the hyperopic shift significantly.

Corneal Endothelial Changes Following Early Capsulotomy Using Neodymium:Yttrium-Aluminum-Garnet Laser

We aimed to survey whether the timing of neodymium:yttrium–aluminum–garnet (Nd:YAG) laser capsulotomy would alter the corneal endothelial morphology and density. A retrospective cohort study was conducted, and 48 patients with unilateral posterior capsular opacity (PCO) and Nd:YAG laser capsulotomy performance were enrolled. The participants were divided into the early Nd:YAG group (timing ≤ 12 months, n = 20) and late Nd:YAG group (timing > 12 months, n= 28) depending on elapsed months between phacoemulsification and Nd:YAG laser capsulotomy. Endothelial cell density (ECD), coefficient of variant (CV), hexagonality (HEX), and central corneal thickness (CCT) between the two groups were collected. A generalized estimate equation was conducted to evaluate the corneal endothelial parameters between the two groups with an adjusted odds ratio (aOR) and 95% confidence interval (CI). The CDVA was improved after treatment in both groups (both p < 0.001). Chronically, ECD in the early group was significantly decreased one week after treatment (2221.50 ± 327.73/mm² vs. 2441.55 ± 321.80/mm², p < 0.001), which recovered to 2369.95 ± 76.37/mm² four weeks after the treatment but was still lower than the preoperative status (p < 0.001). In addition, the HEX percentage showed a significant reduction at four weeks after treatment (p = 0.028). The ECD in the early group was significantly lower than that in the late group (aOR: 0.167, 95% CI: 0.079–0.356, p = 0.003) in both week 1 (p < 0.001) and week 4 (p = 0.004) after laser treatment. In conclusion, the early application of Nd:YAG laser capsulotomy within one year after cataract surgery may be the reason for postoperative ECD decrement without known etiology.

Polydopamine based photodynamic coating on intraocular lens surface for safer posterior capsule opacification conquering

Intraocular lens (IOL) is the indispensable implant for cataract surgery. However, posterior capsular opacification (PCO) happens in high incidence after IOL implantation. PCO is caused by adhesion, proliferation, trans-differentiation of...

An evaluation of the inhibition effects of cell migration of Aspirin soaking 360°square-edge intraocular lens in an in vitro lens capsule model

PURPOSE

This study performs to evaluate the Hydrophobic and Hydrosmart 360°square-edge intraocular lens drug delivery of Aspirin using an in vitro lens capsular model.

METHODS

Cell counting kit-8 assay was used to calculate 50% inhibiting concentration values in both SRA01/04 and HLE-B3 cells. Hoechst staining and transwell assay were used to detect cell proliferation and cell migration. The in vitro lens capsule model was established mainly with a special transwell-col and cell climbing sheet, in which an intraocular lens and the TGF-β2 were added. The ultraviolet spectrophotometer was used to measure the drug concentrations released in vitro. Cell-exclusion zone assay was used to detect the cell migration in the in vitro capsular model.

RESULTS

It shows that cell morphology and distribution of SRA01/04 in the in vitro lens capsular model were closer to those in vivo. The results revealed that there could be significant inhibiting effects on cell migration of the hydrosmart intraocular lens with a sustained drug release in vitro in 7 days, while the hydrophobic intraocular lens drug delivery of Aspirin was mainly performed only from day 1 to day 3.

CONCLUSIONS

Results showed the developed hydrosmart intraocular lens could release Aspirin continuously in vitro to inhibit the cell migration of lens epithelial cells.

Metformin attenuates the epithelial-mesenchymal transition of lens epithelial cells through the AMPK/TGF-β/Smad2/3 signalling pathway

Posterior capsule opacification (PCO) is a common ocular fibrosis disease related to the epithelial-mesenchymal transition (EMT) of human lens epithelial cells (HLECs). However, safe and effective drugs that prevent or treat PCO are lacking. Metformin (Mtf) has been used to treat fibrosis-related diseases affecting many organs and tissues, but its effect on ocular fibrosis-related diseases is unclear. We investigated whether Mtf can inhibit EMT and fibrosis in HLECs to prevent and treat PCO and elucidated the potential molecular mechanism. Here, we established an HLEC model of TGF-β-induced EMT and found that 400 μM Mtf inhibited vertical and lateral migration and EMT-related gene and protein expression in HLECs. Smad2/3 are downstream molecules of TGF-β that enter the nucleus to regulate EMT-related gene expression during the occurrence and development of PCO. We revealed that Mtf suppressed TGF-β-induced Smad2/3 phosphorylation and nuclear translocation. Mtf induces AMP-activated protein kinase (AMPK) phosphorylation. In this study, we found that Mtf induced the activation of AMPK phosphorylation in HLECs. To further explore the mechanism of Mtf, we pretreated HLECs with Compound C (an AMPK inhibitor) to repeat the above experiments and found that Compound C abolished the inhibitory effect of Mtf on HLEC EMT and the TGF-β/Smad2/3 signalling pathway. Thus, Mtf targets AMPK phosphorylation to inhibit the TGF-β/Smad2/3 signalling pathway and prevent HLEC EMT. Notably, we first illustrated the AMPK/TGF-β/Smad2/3 signalling pathway in HLECs, which may provide a new therapeutic strategy for PCO.

Suppression of epithelial to mesenchymal transition markers in mouse lens by a Smad7-based recombinant protein

Cataracts, a clouding of the eye lens, are a leading cause of visual impairment and are responsible for one of the most commonly performed surgical procedures worldwide. Although generally safe and effective, cataract surgery can lead to a secondary lens abnormality due to transition of lens epithelial cells to a mesenchymal phenotype (EMT) and opacification of the posterior lens capsular bag. Occurring in up to 40% of cataract cases over time, posterior capsule opacification (PCO) introduces additional treatment costs and reduced quality of life for patients. Studies have shown that PCO pathogenesis is driven in part by TGF-β, signaling through the action of the family of Smad coactivators to effect changes in gene transcription. In the present study, we evaluated the ability of Smad-7, a well characterized inhibitor of TGF-β -mediated Smad signaling, to suppress the EMT response in lens epithelial cells associated with PCO pathogenesis. Treatment of lens epithelial cells with a cell-permeable form of Smad7 variant resulted in suppressed expression of EMT markers such as alpha smooth muscle actin and fibronectin. A single application of cell-permeable Smad7 variant in the capsular bag of a mouse cataract surgery model resulted in suppression of gene transcripts encoding alpha smooth muscle actin and fibronectin. These results point to Smad7 as a promising biotherapeutic agent for prevention or substantial reduction in the incidence of PCO following cataract surgery.

Precision pulse capsulotomy: Initial clinical experience in simple and challenging cataract surgery cases

PURPOSE

To evaluate precision pulse capsulotomy (PPC) in simple and challenging cataract surgery cases.

SETTING

Clínica Quesada, San Salvador, El Salvador.

DESIGN

Prospective case series.

METHODS

This single-center prospective study assessed cataract surgeries with anterior capsulotomy performed using a PPC device through a 2.2 mm corneal incision in the presence of an ophthalmic viscosurgical device. This was followed by phacoemulsification and intraocular lens implantation. Outcomes included capsulotomy appearance and diameter, surgical complications, and postoperative visual acuity.

RESULTS

The study comprised 38 eyes. All cases resulted in 360-degree complete, round capsulotomies averaging 5.5 mm in diameter with intracapsular IOL fixation. No PPC-related complications were observed intraoperatively or on follow-up at 3 to 8 months. The PPC was useful in challenging cases with corneal opacities that obscured the capsulotomy path or with poorly dilated pupils. Precision pulse capsulotomy occurs instantaneously everywhere along the capsulotomy path, which allowed safe release of subcapsular pressure in intumescent cataracts with consistent creation of a round, appropriately sized capsulotomy. The PPC edge quality was shown in a case with 6 clock hours of zonular dialysis in which iris hooks held the capsulotomy edge for over 45 minutes for removal of a 4+ cataract.

CONCLUSIONS

Precision pulse capsulotomy had a short learning curve and was integrated seamlessly into the surgical routine. The combination of suction with ultrafast capsulotomy provided capsulotomy roundness, sizing, safety, and edge quality that significantly facilitated difficult cases. The ease of use, consistency, and efficiency of PPC capsulotomy might support its use under many practice scenarios.

SNAI1 interacts with HDAC1 to control TGF‑β2‑induced epithelial‑mesenchymal transition in human lens epithelial cells

The opacity of the lens capsule after cataract surgery is caused by epithelial‑to‑mesenchymal transition (EMT) of lens epithelial cells. Snail family transcriptional repressor 1 (SNAI1) is a transcriptional repressor that recruits multiple chromatin enzymes including lysine‑specific histone demethylase 1A, histone deacetylase (HDAC) 1/2, polycomb repressive complex 2, euchromatic histone lysine methyltransferase 2 and suppressor of variegation 3‑9 homolog 1 to the E‑cadherin promoter, thereby suppressing E‑cadherin expression. However, the functional relationship between SNAI1 and HDAC in the induction of EMT in human lens epithelial cells (HLECs) is still unclear. Therefore, the objective of the present study was to explore the possible functional relationship between SNAI1 and HDAC1 in the induction of EMT in HLECs. In the present study, SNAI1 was found to be increased in HLECs during transforming growth factor‑β2 (TGF‑β2)‑induced EMT. Knockdown of SNAI1 by siRNA reversed TGF‑β2‑induced downregulation of E‑cadherin and upregulation of α‑Smooth Muscle Actin. Furthermore, SNAI1 was found to be associated with HDAC1 in the E‑cadherin promoter in TGF‑β2‑treated HLECs. Inhibition of HDAC by trichostatin A and suberoylanilide hydroxamic acid could prevent TGF‑β2‑induced EMT in HLECs. Collectively, SNAI1 interacted with HDAC1 to repress E‑cadherin in the TGF‑β2‑induced EMT in HLECs, suggesting that HDAC inhibitors may have potential therapeutic value for the prevention of EMT in HLECs.

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.

Clinical application of accommodating intraocular lens

The present review describes recent advances in application of accommodating intraocular lenses (AIOLs). Standard monofocal intraocular lenses (MIOLs) only correct distance vision, while AIOLs are designed to allow both good distance vision and near vision, which is achieved through the contraction and relaxation of ciliary muscles by providing transformation of the axial movement or curvature of the lens. Thus, AIOLs may be a better choice for those patients who demand a higher level of visual performance. Since techniques to analyze the performance of AIOLs have not been standardized, and there is a variety of both subjective and objective methods, it is hard to measure the performance of these intraocular lenses. By evaluating advantages and disadvantages of various AIOLs, and introducing techniques for measurement the performance postoperative, this paper can provide some relative information on choosing the type of AIOLs in the clinic.

Aldo-Keto Reductases: Multifunctional Proteins as Therapeutic Targets in Diabetes and Inflammatory Disease

Aldose reductase (AR) is an NADPH-dependent aldo-keto reductase that has been shown to be involved in the pathogenesis of several blinding diseases such as uveitis, diabetic retinopathy (DR) and cataract. However, possible mechanisms linking the action of AR to these diseases are not well understood. As DR and cataract are among the leading causes of blindness in the world, there is an urgent need to explore therapeutic strategies to prevent or delay their onset. Studies with AR inhibitors and gene-targeted mice have demonstrated that the action of AR is also linked to cancer onset and progression. In this review we examine possible mechanisms that relate AR to molecular signaling cascades and thus explain why AR inhibition is an effective strategy against colon cancer as well as diseases of the eye such as uveitis, cataract, and retinopathy.

German claims data analysis to assess impact of different intraocular lenses on posterior capsule opacification and related healthcare costs

Aim

Cataract extraction is one of the most frequent surgeries in Germany. In most cases, the clouded natural lens is replaced by a hydrophobic or hydrophilic acrylic intraocular lens (IOL) implant. The most common long-term complication after cataract surgery is the development of a posterior capsule opacification (PCO). Although no precise real world data are available, published evidence suggests a lower risk for PCO development for hydrophobic acrylic IOLs compared to hydrophilic acrylic IOLs. Therefore, in the present study we assessed real world data on the impact of different IOL material types on the incidence of post-operative PCO treatment.

Subject and methods

In this retrospective study, we included 3,025 patients who underwent cataract extraction and implantation of either an acrylic hydrophobic or hydrophilic IOL in 2010. We assessed clinical outcomes and direct costs in a 4-year follow-up period after cataract surgery from a statutory health insurance (SHI) perspective in Germany.

Results

PCO that required capsulotomies occurred significantly (p < 0.0001) less frequent in patients who had received a hydrophobic IOL (31.57% of 2,078 patients) compared to the group with hydrophilic IOL implants (56.6% of 947 patients) and costs per patient for postoperative treatment in a 4-year follow-up were 50.03 € vs. 87.81 € (i.e. 75% higher in the latter group, p < 0.0001).

Conclusion

Considering the high prevalence of cataract, the economic burden associated with adverse effects of cataract extraction is of great relevance for the German SHI. Hydrophobic lenses seem to be superior regarding both medical and economic results.

Visual Performance after Bilateral Implantation of a Four-Haptic Diffractive Toric Multifocal Intraocular Lens in High Myopes

Background. The vision with diffractive toric multifocal intraocular lenses after cataract surgery in long eyes has not been studied previously. Objectives. To report visual performance after bilateral implantation of a diffractive toric multifocal intraocular lens in high myopes. Methods. Prospective, observational case series to include patients with axial length of ≥26 mm and corneal astigmatism of >1 dioptre who underwent bilateral AT LISA 909M implantation. Postoperative examinations included photopic and mesopic distance, intermediate, and near visual acuity; photopic contrast sensitivity; visual symptoms (0–5); satisfaction (1–5); and spectacle independence rate. Results. Twenty-eight eyes (14 patients) were included. Postoperatively, mean photopic monocular uncorrected distance, intermediate, and near visual acuities (logMAR) were 0.12 ± 0.20 (standard deviation), 0.24 ± 0.16, and 0.29 ± 0.21, respectively. Corresponding binocular values were −0.01 ± 0.14, 0.13 ± 0.12, and 0.20 ± 0.19, respectively. One eye (4%) had one-line loss in vision. Under mesopic condition, intermediate vision and near vision decreased significantly (all P ≤ 0.001). Contrast sensitivity at all spatial frequencies did not improve significantly under binocular condition (all P > 0.05). Median scores for halos, night glare, starbursts, and satisfaction were 0.50, 0.00, 0.00, and 4.25, respectively. Ten patients (71%) reported complete spectacle independence. Conclusions. Bilateral implantation of the intraocular lens in high myopes appeared to be safe and achieved good visual performance and high satisfaction.

Aldose Reductase Mediates Transforming Growth Factor β2 (TGF-β2)-Induced Migration and Epithelial-To-Mesenchymal Transition of Lens-Derived Epithelial Cells

PURPOSE

Cataract surgery involves removal of lens tissue, but is associated with a high complication rate due to regrowth of residual lens epithelial cells to produce posterior capsule opacification (PCO) and diminished visual acuity. As inhibitors of aldose reductase (AR) have been shown to suppress markers of PCO, our studies were designed to identify a role for AR in the pathogenesis of PCO.

METHODS

Sorbinil-mediated AR inhibition was determined by measuring sorbitol accumulation. Cell migration was measured using both transwell and scratch assays. Proteins in the SMAD signaling pathway were measured by Western blotting. The interactions of AR and SMADs were demonstrated by co-immunoprecipitation (Co-IP) and proximity ligation assay (PLA). Epithelial-to-mesenchymal transition (EMT) expression was measured by Western blot and quantitative PCR (q-PCR). Matrix metalloproteinase (MMP)-2 and MMP-9 activities were measured in conditioned medium by zymography.

RESULTS

We observed that either Sorbinil-mediated AR inhibition or siRNA-mediated AR gene knockdown prevented migration of lens epithelial cells following exposure to TGF-β2. AR inhibition or AR knockdown reduced SMAD and MMP activation triggered by TGF-β2. In addition, we demonstrated AR inhibition or AR knockdown decreased TGF-β2-induced expression of EMT markers. Co-IP studies and PLA were used to demonstrate that AR and SMAD2 interact either directly or in close concert with additional factor(s) in a nonenzymatic manner.

CONCLUSIONS

This study demonstrates that AR participates in the response of lens epithelial cells to TGF-β2. Our studies raise the possibility that AR inhibition may be effective in preventing development of PCO by disrupting the TGF-β2/SMAD pathway.

Adhesion study of cultured human lens capsule cells on hydrophilic intraocular lenses coated with polyethylene glycol

PURPOSE

To evaluate the adhesion of human lens capsule cells on hydrophilic acrylic intraocular lenses (IOLs) coated with polyethylene glycol (PEG).

SETTING

Department of Ophthalmology, Faculty of Medicine, Universidade Estadual Paulista-Botucatu, São Paulo, Brazil.

DESIGN

Experimental study.

METHODS

Human anterior lens capsules obtained during cataract surgery were cultured and seeded (200 cells/IOLs) in triplicates on the surface of a copolymer comprising hydroxyethyl methacrylate, ethyl methacrylate, and methyl methacrylate IOLs (Loflex) treated or not treated with PEG. After 26 hours, the number of viable adherent cells was estimated by counting in a hemocytometer.

RESULTS

The coating of hydrophilic acrylic IOLs with PEG was effective in inhibiting cell adhesion (P < .05). Cells showing 2 distinct morphologic patterns-epithelial and dendritic-like-were observed during the in vitro establishment of the cultures. A tendency toward greater adhesion of dendritic-like cells was observed in untreated IOLs compared with treated IOLs (P = .095).

CONCLUSION

Coating hydrophilic acrylic IOLs with PEG was effective in inhibiting cell adhesion. This treatment might play a role in posterior capsule opacification prevention.

FINANCIAL DISCLOSURE

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

The assessment of changes in macular thickness in diabetic and non-diabetic patients: the effect of topical ketorolac on macular thickness change after ND:YAG laser capsulotomy

PURPOSE

The purpose of our study is to assess the changes in macular thickness (MT) in diabetic and non-diabetic patients and to research effects of topical ketorolac (Acular®, Allergan, Irvine, CA) on MT change after neodymium:yttrium aluminum garnet (Nd:YAG) laser capsulotomy.

MATERIAL AND METHODS

This study involved 88 eyes of 88 patients diagnosed as posterior capsule opacification (PCO). Patients were divided into four groups according to presence of diabetes mellitus (DM) and drugs used after capsulotomy. Group 1: Patients with DM using only 0.1% Fluorometholon (FML®, Allergan, Irvine, CA) after capsulotomy (22 patients). Group 2: Patients with DM using 0.5% ketorolac (Acular®) and 0.1 Fluorometholon (FML®, Allergan, Irvine, CA) after capsulotomy (20 patients). Group 3: Patients without DM using only 0.1% Fluorometholon (FML®, Allergan, Irvine, CA) (22 patients). Group 4: Patients without DM using 0.5% ketorolac (Acular®) and 0.1% Fluorometholon (FML®, Allergan, Irvine, CA) (24 patients). A plus-shaped capsulotomy was performed using VISULAS® YAGIII (Carl Zeiss) laser microscope. MT measurement with Cirrus SD-OCT (Carl Zeiss Opthalmic System Inc., Model 400, Dublin, CA, Software 5) were done. Measurements were done before laser, and on the first day, first week, first month, third month and sixth month after laser capsulotomy. We compared the four groups for MT change during 6 months.

RESULTS

Group 1 involving patients with DM using only 0.1% Fluorometholon (FML®, Allergan, Irvine, CA) after capsulotomy had increased MT at the first week, and the first, third, and sixth month after laser (p < 0.001). Group 3 involving patients without DM using only 0.1% Fluorometholon (FML®, Allergan, Irvine, CA) had increased MT at the first week, and at the first and third month, there was no statistically significant difference at the sixth month (p > 0.05). There was no statistically significant increase in MT during the follow-up period in group 2 involving patients with DM using 0.5% ketorolac (Acular®) and 0.1 Fluorometholon (FML®, Allergan, Irvine, CA) after capsulotomy and group 4 involving patients without DM using 0.5% ketorolac (Acular®) and 0.1% Fluorometholon (FML®, Allergan, Irvine, CA) (p > 0.05).

CONCLUSION

An increase in MT can be observed after Nd:YAG laser capsulotomy, especially in diabetic patients. Adding topical ketorolac (Acular®, Allergan, Irvine, CA) to topical Fluorometholon (FML®, Allergan, Irvine, CA) therapy after YAG laser capsulotomy can prevent this increase.

Posterior Capsule Opacification After Phacoemulsification: Annual Review

PURPOSE

The purpose of this article is to provide a clinical update on posterior capsule opacification (PCO) after phacoemulsification by reviewing the literature from the last 12 months.

DESIGN

This article is a literature review.

METHODS

The authors conducted a 1-year literature search in the English language on PCO using PubMed. The period used to conduct the literature search was from January 1, 2013, to January 1, 2014. The following search terms were used during the PubMed search: phacoemulsification, microcoaxial incision, posterior capsule opacification, long-term evaluation of intraocular lens (IOL) implantation, IOL edge design and material, surgical technique, anterior capsule overlap on the IOL optic, diabetes mellitus, myopia, pseudoexfoliation, retinitis pigmentosa, uveitis, and neodymium: yttrium-aluminum-garnet laser capsulotomy.

RESULTS

This review incorporates original articles that provided fresh insights and updates on PCO. Particular attention was paid to observational, randomized, controlled clinical trials, as well as analyses of larger cohorts with a prospective and retrospective study design. Letters to the editor, unpublished works, experimental trials and abstracts were not considered.

CONCLUSIONS

This annual review provides a brief update on PCO that might be of interest to the practicing clinical ophthalmologist.

Economic considerations related to choice of intraocular lens (IOL) and posterior capsule opacification frequency - a comparison of three different IOLs

PURPOSE

To evaluate the posterior capsule opacification (PCO) rates in three different modern standard intraocular lenses (IOL) and analyse the related cost.

METHODS

Retrospective study of medical records from 1527 patients who underwent uneventful cataract surgery by phacoemulsification with posterior chamber implantation of either AcrySof SN60 (n = 375), Akreos Adapt (n = 350) or Tecnis Acryl IOL (n = 801). All surgeries were performed by the same surgeon using the same surgical technique and equipment. Primary end-point was neodymium:yttrium-aluminium-garnet (Nd:YAG) capsulotomy for visual impairment secondary to PCO. Cost of IOL material and Nd:YAG capsulotomy for PCO was then evaluated and compared between the IOLs.

RESULTS

Mean follow-up was 41.5 months, and the only statistically significant variable of developing PCO was IOL type and individual follow-up time. Nd:YAG capsulotomy was performed in 7.47% in the AcrySof group, 17.71% in the Akreos group and 3.75% in the Tecnis group. Average cost for Nd:YAG capsulotomy per surgery was €18.75 in the AcrySof SN60 group, €44.25 in the Akreos Adapt group and €9.25 in the Tecnis Acryl group. The combined cost of cataract surgery and PCO treatment was €9.81 higher in for the Akreos Adapt group than the other two combined.

CONCLUSIONS

This retrospective study shows that the risk of PCO and Nd:YAG capsulotomy is significantly higher in hydrophilic Akreos IOL compared with both AcrySof and Tecnis hydrophobic IOLs. The increased risk of PCO in the hydrophilic IOL is related to higher total average costs for cataract surgery.

The roles of αV integrins in lens EMT and posterior capsular opacification

Posterior capsular opacification (PCO) is the major complication arising after cataract treatment. PCO occurs when the lens epithelial cells remaining following surgery (LCs) undergo a wound healing response producing a mixture of α-smooth muscle actin (α-SMA)-expressing myofibroblasts and lens fibre cells, which impair vision. Prior investigations have proposed that integrins play a central role in PCO and we found that, in a mouse fibre cell removal model of cataract surgery, expression of αV integrin and its interacting β-subunits β1, β5, β6, β8 are up-regulated concomitant with α-SMA in LCs following surgery. To test the hypothesis that αV integrins are functionally important in PCO pathogenesis, we created mice lacking the αV integrin subunit in all lens cells. Adult lenses lacking αV integrins are transparent and show no apparent morphological abnormalities when compared with control lenses. However, following surgical fibre cell removal, the LCs in control eyes increased cell proliferation, and up-regulated the expression of α-SMA, β1-integrin, fibronectin, tenascin-C and transforming growth factor beta (TGF-β)-induced protein within 48 hrs, while LCs lacking αV integrins exhibited much less cell proliferation and little to no up-regulation of any of the fibrotic markers tested. This effect appears to result from the known roles of αV integrins in latent TGF-β activation as αV integrin null lenses do not exhibit detectable SMAD-3 phosphorylation after surgery, while this occurs robustly in control lenses, consistent with the known roles for TGF-β in fibrotic PCO. These data suggest that therapeutics antagonizing αV integrin function could be used to prevent fibrotic PCO following cataract surgery.

RNA Interference Targeting Snail Inhibits the Transforming Growth Factor β 2-Induced Epithelial-Mesenchymal Transition in Human Lens Epithelial Cells

Epithelial-msenchymal transition (EMT) contributes to posterior capsule opacification (PCO) type of cataract. Transcription factors Snail is a key trigger of EMT activated by transforming growth factor β (TGFβ). This study was done to investigate the effect of Snail targeting siRNA on TGFβ2-induced EMT in human lens epithelial cells. TGFβ2 treatment of cultured human epithelial cell line (HLEB3) upregulated the expression of Snail and the EMT relevant molecules such as vimentin and α-SMA but downregulated the expression of keratin and E-cadherin. After the stimulation of TGFβ2, the HLEB3 cells became fibroblast-like in morphology, and the junctions of cell-cell disappeared. TGFβ2 treatment also enhanced migration ability of HLEB3 cells. TGFβ2-induced Snail expression and EMT were significantly inhibited by Snail siRNA. By analyzing the response characteristics of HLEB3 in TGFβ2-induced EMT model with/without Snail-specific siRNA, we concluded that Snail is an element in the EMT of HLEB3 cells induced by TGFβ2. Snail siRNA targeting can block the induced EMT and therefore has the potential to suppress the development of PCO.

Posterior capsular opacification in patients with pseudoexfoliation syndrome: a long-term perspective

PURPOSE

To compare posterior capsular opacification in patients with and without pseudoexfoliation syndrome 6-7 years following surgery.

METHODS

Forty-four eyes of 44 patients with pseudoexfoliation syndrome who underwent cataract surgery with phacoemulsification in 2001 and 2002 were available for follow-up in 2008. These patients were compared to 86 age- and gender-matched patients (86 eyes) without pseudoexfoliation syndrome who had surgery during the same time period. Posterior capsule opacification was assessed using digital retroillumination photography. The images were analysed with a software program (POCOman) to determine the extent and severity of the capsular opacification.

RESULTS

Percentage and severity of posterior capsular opacification within the central 4.0 and 1.3 mm of the optical zone were compared in eyes with and without pseudoexfoliation syndrome. Neither of these results were statistically significant. Before the re-examination in 2008, neodymium:yttrium-aluminium-garnet laser posterior capsulotomy had been conducted in 16% (n = 7) of eyes with pseudoexfoliation syndrome, as well as in 16% (n = 14) of eyes without pseudoexfoliation syndrome.

CONCLUSION

Our study indicates that, with phacoemulsification, development of long-term posterior capsular opacification is not increased in patients with pseudoexfoliation syndrome after uncomplicated cataract surgery.

Polymethoxyflavones as agents that prevent formation of cataract: nobiletin congeners show potent growth inhibitory effects in human lens epithelial cells

Posterior capsular opacification (PCO) is the most frequent complication and the primary reason for visual decrease after extracapsular cataract surgery. The proliferation and migration of leftover lens epithelial cells (LECs) after surgery may contribute to the development of PCO. To prevent PCO, a rational approach would be to inhibit both the proliferation and the migration of LECs using nontoxic xenobiotics. Nobiletin, one of the most abundant polymethoxyflavones (PMFs) in citrus peel, and its synthetic congeners displayed a potent inhibition of LEC proliferation. Structural features which enhance anti-proliferative activity have also been discussed.

CD44 expression is developmentally regulated in the mouse lens and increases in the lens epithelium after injury

Hyaluronan is an oligosaccharide found in the pericellular matrix of numerous cell types and hyaluronan-induced signaling is known to facilitate fibrosis and cancer progression in some tissues. Hyaluronan is also commonly instilled into the eye during cataract surgery to protect the corneal endothelium from damage. Despite this, little is known about the distribution of hyaluronan or its receptors in the normal ocular lens. In this study, hyaluronan was found throughout the mouse lens, with apparently higher concentrations in the lens epithelium. CD44, a major cellular receptor for hyaluronan, is expressed predominately in mouse secondary lens fiber cells born from late embryogenesis into adulthood. Surgical removal of lens fiber cells from adult mice resulted in a robust upregulation of CD44 protein, which preceded the upregulation of alpha-smooth muscle actin expression typically used as a marker of epithelial-mesenchyma transition in this model of lens epithelial cell fibrosis. Mice lacking the CD44 gene had morphologically normal lenses with a response to lens fiber cell removal similar to wildtype, although they exhibited an increase in cell-associated hyaluronan. Overall, these data suggest that lens cells have a hyaluronan-containing pericellular matrix whose structure is partially regulated by CD44. Further, these data indicate that CD44 upregulation in the lens epithelium may be an earlier marker of lens injury responses in the mouse lens than the upregulation of alpha-smooth muscle actin.

Determination of albumin sorption to intraocular lenses by radiolabeling and confocal laser scanning microscopy

PURPOSE

To determine albumin adsorption profiles and penetration depth of 3 intraocular lens (IOL) materials over time using confocal laser scanning microscopy (CLSM) and radiolabeling.

SETTING

Centre for Contact Lens Research, School of Optometry, and Department of Biology, University of Waterloo, Waterloo, Ontario, Canada.

METHODS

Poly(methyl methacrylate) (PMMA), silicone, and foldable hydrophilic acrylic IOLs were incubated in 0.5 mg/mL bovine serum albumin (BSA) for 1, 7, and 14 days. The BSA was conjugated with lucifer yellow VS to allow identification of the protein location by fluorescent imaging with CLSM. Next, the protein uptake was quantified using 2% (125)I-labeled BSA.

RESULTS

Confocal laser scanning microscopy showed increasing BSA uptake for silicone and PMMA IOLs after 14 days of incubation (P<.05), with an apparent penetration depth of 8.7 microm +/- 1.9 (SD) and 9.2 +/- 1.4 microm, respectively. For hydrophilic acrylic IOLs, BSA was detected at a depth of 38 +/- 7.4 microm after 1 day, followed by an increase to 192.7 +/- 16.2 microm after 14 days. Despite the penetration depth into the hydrophilic acrylic IOLs, quantitative results confirmed that PMMA and hydrophilic acrylic deposited significantly less BSA (mean 278.3 +/- 41.7 ng and 296.5 +/- 33.1 ng, respectively) than silicone IOLs (mean 392.6 +/- 37.6 ng) (P<.05).

CONCLUSIONS

Silicone and PMMA IOL materials showed BSA sorption near the lens surface only, while BSA penetrated deep into the hydrophilic acrylic IOL matrix. Combining the qualitative CLSM method and quantitative radiolabeling technique provided detailed information on protein interactions with implantable biomaterials.

Prevention of posterior capsular opacification through aldose reductase inhibition

PURPOSE

The purpose of this study was to evaluate the effect of aldose reductase (AR) inhibition on posterior capsular opacification (PCO) with the use of a pig eye capsular bag model.

METHODS

Pig eye capsular bags were prepared by capsulorhexis and cultured in medium without or with AR inhibitors for 7 days. Immunostaining was performed in paraformaldehyde-fixed capsular bags to determine the expression of proliferating cell nuclear antigen (PCNA), alpha-smooth muscle actin (SMA), beta-crystallin, and intercellular adhesion molecule (ICAM)-1. The effect of AR inhibition on basic fibroblast growth factor (BFGF)-induced mitogenic signaling in cultured human lens epithelial cells (HLECs) was examined. Cell growth was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay and cell counting, the expression of alpha-SMA, beta-crystallin, and ICAM-1 by Western blot and immunocytochemical analysis, protein kinases by Western blot analysis, and NF-kappaB activation by gel shift and reporter assays.

RESULTS

During culture of pig eye capsular bags, residual cells on both the anterior and the posterior capsule showed vigorous growth. Treatment with AR inhibitors significantly prevented the lens epithelial cell growth in capsular bags and expression of alpha-SMA, beta-crystallin, and ICAM-1. HLECs showed a dose-dependent response to BFGF, proliferation at lower concentrations (<20 ng/mL) and differentiation/transdifferentiation at higher concentrations (>50 ng/mL). Inhibition of AR also prevented the BFGF-induced activation of ERK1/2, JNK, and NF-kappaB in HLECs.

CONCLUSIONS

Results suggest that AR is required for lens epithelial cell growth and differentiation/transdifferentiation in the capsular bags, indicating that inhibition of AR could be a potential therapeutic target in the prevention of PCO.

Biocompatibility of intraocular lens materials

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

Cataract and glaucoma surgery in pseudoexfoliation syndrome: a review

Pseudoexfoliation syndrome is a risk factor in cataract surgery because of the increased weakness of zonular apparatus and reduced pupillary dilatation. The surgical outcome of using phacoemulsification in the central zone, inducing minimal stress on the zonules, inserting a capsular tension ring in selected cases, and stretching the pupil mechanically in eyes with miotic pupils, may turn out to be uneventful in most cases. Postoperative fibrosis with subsequent shrinkage of the capsule is increased in these eyes, and these centripetal forces will further loosen the zonular fibres. Late in-the-bag intraocular lens dislocation is therefore anticipated to become a growing problem in the future. Despite the dysfunctioning of the blood-aqueous barrier in eyes with pseudoexfoliation syndrome, the frequency of postoperative inflammatory reaction is low due to the improvements made in surgical technique and equipment in recent years. Glaucoma frequently occurs in eyes with pseudoexfoliation syndrome. Compared with primary open-angle glaucoma, optic damage is more pronounced in these eyes at the time of diagnosis and response to medical therapy is poorer. Although responses to argon laser therapy and filtering surgery are roughly similar between the two types of glaucoma, there are indications that primary laser trabeculoplasty has a higher success rate in pseudoexfoliation glaucoma than in primary open-angle glaucoma.

Status of toric intraocular lenses

PURPOSE OF REVIEW

To provide an update on the status of toric intraocular lenses. These lenses can be used as an alternative or adjunct to corneal astigmatic incisions for correcting preexisting astigmatism in patients with cataracts. They are a particularly attractive option in those cases where limbal-relaxing incisions are not powerful or predictable enough. Other toric lenses may correct astigmatism in addition to spherical refractive errors in phakic patients.

RECENT FINDINGS

Toric lenses have continued to gain popularity with the US Food and Drugs Administration (FDA) approval of the Acrysof Toric intraocular lenses. This lens is designed to be implanted in patients undergoing cataract removal and who have significant preexisting corneal astigmatism. In the FDA clinical trial, study patients received one of the three cylindrical powers, and control patients received a standard monofocal intraocular lenses. The study found that the Acrysof Toric intraocular lenses provided excellent visual outcomes and exhibited excellent rotational stability. With the Acrysof Toric intraocular lenses, the average lens rotation was less than 4 degrees from the lens' initial placement at 6 months after surgery.

SUMMARY

Toric intraocular lenses provide excellent vision for astigmatic cataract patients, and new designs are significantly improving visual acuity by minimizing the risk of rotation.

Lens cell targetting for gene therapy of prevention of posterior capsule opacification

Posterior capsule opacification is the main complication of cataract surgery. Using adenovirus-mediated gene transfer, we recently reported that it was feasible to prevent PCO by overexpressing pro-apoptotic molecules such as pro-caspase 3 or Bax in the residual lens epithelial cells post-cataract surgery. However, this approach is feasible only if gene transfer can be restricted to the residual cells responsible for PCO. Initially, we tested an adenovirus (human serotype 5, HAd5), a lentivirus (HIV) and an oncoretrovirus (MLV) vector for the their in vivo transduction efficiency of rabbit lens cells. We found that HAd5 vectors were the most efficient (>90% of the cells could be transduced). Six potential lens-specific promoters were then cloned into HAd5 vectors and assayed for their ability to target expression to a specific population of cells, using in vitro, ex vivo and in vivo rabbit tissues and human lens capsular bags. We found that the LEP503, MIP and Filensin promoters induced strong lens-specific expression of a reporter gene, in human lens cells. Following this ex vivo assay, we showed in a rabbit PCO model that gene transfer could be spatially restricted to the capsular bag by confining the vector with Matrigel. Our combined approach using a lens-specific promoter and a biocompatible gel should render feasible a novel therapeutic strategy for PCO that targets the remaining lens cells.