INTRAVITREAL METHOTREXATE INJECTION FOR THE TREATMENT AND PREVENTION OF PROLIFERATIVE VITREORETINOPATHY.

PURPOSE: To report on our experience using intravitreal methotrexate (MTX) in patients with retinal detachment associated with proliferative vitreoretinopathy and/or open globe injury. METHODS: This study performed a retrospective chart review of a consecutive series of 21 eyes of 21 patients who underwent serial intravitreal MTX injection for treatment and/or prevention of proliferative vitreoretinopathy from December 2021 to January 2024. RESULTS: Twenty-one patients underwent pars plana vitrectomy, membrane peeling, laser photocoagulation, silicone oil infusion, and intravitreal MTX injection. Postoperatively, all eyes received a series of intravitreal MTX (400 µg/0.1 mL) injections. Optimally, injections were administered weekly for 8 weeks and every 2 weeks for four weeks for a total of 13 injections, beginning intraoperatively at the conclusion of retinal reattachment surgery. Mean baseline preoperative and postoperative visual acuity was logarithm of the minimum angle of resolution 3.2 (approximately hand motions vision) and 2.5 (between CF and hand motions vision), respectively, yielding an average improvement in visual acuity of 0.7 logarithm of the minimum angle of resolution units (0 ETDRS lines/letters). These 21 patients received an average of 10.5 injections. With a single operation, detachments in 19 (90%) of 21 eyes were successfully reattached. Corneal epithelial defects were noted in 7 (33%) of 21 patients. CONCLUSION: Serial intravitreal MTX injection was associated with 90% single operation retinal reattachment rate in the setting of retinal detachment with proliferative vitreoretinopathy or retinal detachment at high risk of proliferative vitreoretinopathy.

Intravitreal Injection of Bevacizumab for the Prevention of Postoperative Proliferative Vitreoretinopathy in High-Risk Patients Selected by Laser Flare Photometry.

INTRODUCTION: To evaluate the effect of an intravitreal injection of bevacizumab at the time of rhegmatogenous retinal detachment (RRD) surgery, on postoperative proliferative vitreoretinopathy (PVR) in high-risk patients selected by laser flare photometry. METHODS: This single-center observational retrospective cohort study included 137 consecutive patients who underwent pars plana vitrectomy and gas tamponade for primary RRD with increased aqueous flare between July 2016 and June 2021. From June 2019, an intravitreal injection of bevacizumab was administered as an adjunct to RRD repair. Patients who underwent surgery before this time and who did not receive intravitreal bevacizumab served as controls. The main outcome was the rate of retinal redetachment due to PVR. RESULTS: The median flare value was 22.0 (16.5-36.5) pc/ms in the control group and 28.2 (19.7-41.0) pc/ms in the bevacizumab group (p = 0.063). Eyes treated with bevacizumab were more likely to have macula-off RRD (p = 0.003), grade B PVR (p = 0.038), and worse visual acuity (p = 0.004) than controls. The rate of PVR redetachment was significantly lower in the bevacizumab group (11.1%) than in the control (30.1%) (p = 0.012). This difference was more pronounced after adjusting for potential confounding factors (p = 0.005); the risk of developing PVR was 4.5-fold higher in controls (95% CI, 1.6-12.8). After adjustment, the final median visual acuity was also significantly higher in eyes treated with bevacizumab (p = 0.025). CONCLUSION: This pilot study provides preliminary evidence that bevacizumab may reduce the risk of PVR-related recurrent RRD and improve visual outcomes in high-risk patients selected by laser flare photometry.

Steroid Drugs as an Adjunct for Reducing the Incidence of Proliferative Vitreoretinopathy after Rhegmatogenous Retinal Detachment Surgery: A Meta-Analysis of Randomized Controlled Studies.

INTRODUCTION: The efficacy and influence of steroids for reducing the incidence of proliferative vitreoretinopathy (PVR) after rhegmatogenous retinal detachment (RRD) surgery remain controversial. Systematic review and meta-analysis were conducted to explore the effect of steroids versus placebo on risk of PVR. METHODS: We searched PubMed, Embase, Web of science, EBSCO, and Cochrane library databases through September 2020 for randomized controlled trials (RCTs), assessing the effect of steroid drugs as an adjunct for reducing the incidence of PVR after RRD surgery. This meta-analysis was performed using the random-effect model. Data were extracted by two reviewers independently; the quality of RCTs was assessed by the Cochrane risk-of-bias tool. We calculated risk ratio (RR) and the 95% confidence intervals (CIs) of all outcomes and plotted on forest plots. I2 accessed using the χ2 test was applied to quantify the degree of heterogeneity. RESULTS: Four RCTs involving 478 patients (478 eyes) are included in the meta-analysis. There was no significant difference in the incidence of PVR recurrence between steroid groups and control groups (RR: 0.87, 95% CI: 0.70-1.08, p = 0.19). However, the incidence of recurrent PVR was lower in the steroid group (RR: 0.67, 95% CI: 0.46-0.99, p = 0.04) than in the control group when only PVR grades A and B were taken into consideration. Besides, steroids could significantly reduce the incidence of macular edema after surgery (RR: 0.64, 95% CI: 0.47-0.88, p = 0.007). The steroid group and control group had comparable outcomes of retinal reattachment rate and reoperation rate after primary surgery. Additionally, there was no significant difference of the incidence of epiretinal membrane, and the incidence of surgery required by epiretinal membrane. CONCLUSION: This meta-analysis reveals that RRD surgery combined with steroid drugs administration could significantly reduce the recurrence in PVR grade A and B subgroup, as well as the incidence of macular edema after surgery.

Intravitreal 5-Fluorouracil and Heparin to Prevent Proliferative Vitreoretinopathy: Results from a Randomized Clinical Trial.

PURPOSE: Proliferative vitreoretinopathy (PVR) is the major cause for surgical failure after primary rhegmatogenous retinal detachment (RRD). So far, no therapy has been proven to prevent PVR. Promising results for 5-fluorouracil (5-FU) and low-molecular weight heparin (LMWH) in high-risk eyes have been reported previously. The objective of this trial was to examine the effect of adjuvant intravitreal therapy with 5-FU and LMWH compared with placebo on incidence of PVR in high-risk patients with primary RRD. DESIGN: Randomized, double-blind, controlled, multicenter, interventional trial with 1 interim analysis. PARTICIPANTS: Patients with RRD who were considered to be at high risk for PVR were included. Risk of PVR was assessed by noninvasive aqueous flare measurement using laser flare photometry. METHODS: Patients were randomized 1:1 to verum (200 mg/ml 5-FU and 5 IU/ml dalteparin) and placebo (balanced salt solution) intravitreally applied during routine pars plana vitrectomy. MAIN OUTCOME MEASURES: Primary end point was the development of PVR grade CP (full-thickness retinal folds or subretinal strands in clock hours located posterior to equator) 1 or higher within 12 weeks after surgery. For grading, an end point committee assessed fundus photographs. Secondary end points included best-corrected visual acuity and redetachment rate. A group sequential design with 1 interim analysis was applied using the O'Brien and Fleming boundaries. Proliferative vitreoretinopathy grade CP incidence was compared using a Mantel-Haenszel test stratified by surgeon. RESULTS: A total of 325 patients in 13 German trial sites had been randomized (verum, n = 163; placebo, n = 162). In study eyes, mean laser flare was 31 ± 26 pc/ms. No significant difference was found in PVR rate. Primary analysis in the modified intention-to-treat population results were: verum 28% vs. placebo 23% (including not assessable cases as failures); odds ratio [OR], 1.25; 95% confidence interval [CI], 0.76-2.08; P = 0.77. Those in the per-protocol population were: 12% vs. 12%; OR, 1.05; 95% CI, 0.47-2.34; P = 0.47. None of the secondary end points showed any significant difference between treatment groups. During the study period, no relevant safety risks were identified. CONCLUSIONS: Rate of PVR did not differ between adjuvant therapy with 5-FU and LMWH and placebo treatment in eyes with RRD.

METTL3 attenuates proliferative vitreoretinopathy and epithelial-mesenchymal transition of retinal pigment epithelial cells via wnt/ß-catenin pathway.

Proliferative vitreoretinopathy (PVR) is a refractory vitreoretinal fibrosis disease, and epithelial-mesenchymal transition (EMT) of retinal pigment epithelial (RPE) cells is the key pathological mechanism of PVR. However, few studies focused on the role of METTL3, the dominating methyltransferase for m6A RNA modification in PVR pathogenesis. Immunofluorescence staining and qRT-PCR were used to determine the expression of METTL3 in human tissues. Lentiviral transfection was used to stably overexpress and knockdown METTL3 in ARPE-19 cells. MTT assay was employed to study the effects of METTL3 on cell proliferation. The impact of METTL3 on the EMT of ARPE-19 cells was assessed by migratory assay, morphological observation and expression of EMT markers. Intravitreal injection of cells overexpressing METTL3 was used to assess the impact of METTL3 on the establishment of the PVR model. We found that METTL3 expression was less in human PVR membranes than in the normal RPE layers. In ARPE-19 cells, total m6A abundance and the METTL3 expression were down-regulated after EMT. Additionally, METTL3 overexpression inhibited cell proliferation through inducing cell cycle arrest at G0/G1 phase. Furthermore, METTL3 overexpression weakened the capacity of TGFß1 to trigger EMT by regulating wnt/ß -catenin pathway. Oppositely, knockdown of METTL3 facilitated proliferation and EMT of ARPE-19 cells. In vivo, intravitreal injection of METTL3-overexpressing cells delayed the development of PVR compared with injection of control cells. In summary, this study suggested that METTL3 is involved in the PVR process, and METTL3 overexpression inhibits the EMT of ARPE-19 cells in vitro and suppresses the PVR process in vivo.

Intravitreal connective tissue growth factor neutralizing antibody or bevacizumab alone or in combination for prevention of proliferative vitreoretinopathy in an experimental model.

Connective tissue growth factor (CTGF) is released by retinal pigment epithelial (RPE) cells and detectable in proliferative membranes (PrMs). This experimental study was performed to investigate the mRNA and protein levels of both CTGF and vascular endothelial growth factor A (VEGF-A) in a rabbit model of proliferative vitreoretinopathy (PVR). In addition, the effects of a single intravitreal injection of the safe dose of anti-CTGF or bevacizumab as monotherapy and in combination were evaluated. PVR was induced in the right eye of albino rabbits by intravitreal injection of cultured adult human RPE cells. Quantitative real-time reverse transcription PCR (qRT-PCR) and Western blot analysis of CTGF and VEGF-A were performed on whole eye tissue in the PVR model versus controls at different time points. In the next step, the PVR models were assigned to five groups. The monotherapy groups received a single intravitreal injection of 0.1 ml of anti-CTGF 100 µg/ml (final concentration of 6.6 µg/ml in the vitreous) or 0.03 ml of 25 mg/ml bevacizumab. In the combined group, the abovementioned amounts of anti-CTGF and bevacizumab were injected intravitreally from separate sites in one session. No antibody injection was performed in the control group. Intravitreal injection of 0.1 ml of control IgG (1 mg/ml of isotype matched) antibody was performed in the placebo group. After 2 weeks, histologic evaluation including, trichrome staining for collagen, immunostaining by anti-alpha-smooth muscle actin for myofibroblasts, and anti-collagen type-1 antibody on paraffin embedded anterior-posterior sections was done. In addition, fundus photography was performed for clinically equivalent PVR staging. Twenty-four hours following PVR induction, CTGF mRNA and protein levels increased five- and- three-fold compared to controls, respectively (P < 0.001). VEGF-A mRNA and protein levels decreased significantly after 72 h of PVR induction compared to controls (P < 0.05). Means of PrM thickness and myofibroblast cell counts significantly decreased in the anti-CTGF group (P < 0.001 and P < 0.05, respectively). The mean area of collagen type-1 fibers of PrM in the mono- and combination therapy groups that received intravitreal anti-CTGF was significantly reduced (P < 0.001); in addition, mild PVR (stage-1 and 2) formation occurred in comparison with moderate to severe PVR (stage-4 and higher) in other groups. In conclusion, we found that intravitreal injection of CTGF neutralizing antibody resulted in a reduction in PrM thickness, collagen fibers and myofibroblast density in the PVR model. CTGF inhibition may represent a potential therapeutic target for PVR.

Sustained dasatinib treatment prevents early fibrotic changes following ocular trauma.

PURPOSE: Posterior ocular trauma and the subsequent fibrotic retinal complication termed proliferative vitreoretinopathy (PVR) are leading causes of blindness in children and young adults. A previous study suggested that changes occurring within the first month post-trauma can lead to development of PVR later. The aim of this study was to examine the effect of dasatinib, a tyrosine kinase inhibitor clinically used to treat chronic myeloid leukemia, on fibrotic changes occurring within the first month following ocular trauma. METHODS: A previously established swine ocular trauma model that mimics both contusion and penetrating injuries was used. Dasatinib was administered on days 4 and 18 post-trauma via intravitreal injection of either bolus solution or suspension of a sustained release system incorporated in biodegradable poly (lactic-co-glycolic acid) (PLGA) nanoparticles. Animals were followed up to day 32, and the development of traction full-thickness fold in the posterior retina was assessed. RESULTS: A full-thickness retinal fold extending from the wound site developed in 3 out of 4 control eyes injected with PLGA nanoparticles alone at 1 month. Administration of dasatinib solution had little preventative effect with 6 out of 7 eyes developing a fold. In contrast, dasatinib-incorporated PLGA nanoparticle injection significantly reduced the incidence of fold to 1 out of 10 eyes. CONCLUSIONS: Injection of dasatinib-incorporated PLGA significantly reduced early fibrotic retinal changes which eventually lead to PVR following posterior ocular trauma. Thus, our sustained dasatinib release system can potentially be used to both prevent and/or broaden the surgical treatment window for PVR.

BMP7 antagonizes proliferative vitreoretinopathy through retinal pigment epithelial fibrosis in vivo and in vitro.

The major pathogenesis of proliferative vitreoretinopathy (PVR) is that retinal pigment epithelial (RPE) cells undergo epithelial-mesenchymal transition (EMT) because of disordered growth factors, such as TGF-ß, in the vitreous humor. Bone morphogenetic proteins (BMPs) are pluripotent growth factors. In this study, we identified the antifibrotic activity of BMP7 in a PVR model both in vivo and in vitro. BMP7 expression was confirmed on the PVR proliferative membranes. BMP7 was down-regulated in the PVR vitreous humor and TGF-ß-induced RPE cell EMT. In the in vivo studies, BMP7 injection attenuated PVR progression in the eyes of the rabbit model. Additionally, BMP7 treatment maintained RPE cell phenotypes and relieved TGF-ß2-induced EMT, migration, and gel contraction in vitro. BMP7 inhibited the TGF-ß2-induced up-regulation of fibronectin and α-smooth muscle actin and the down-regulation of E-cadherin and zona occludens-1 by balancing the TGF-ß2/Smad2/3 and BMP7/Smad1/5/9 pathways. These findings provide direct evidence of the ability of BMP7 in PVR inhibition and the potential of BMP7 for use in PVR therapeutic intervention.-Yao, H., Ge, T., Zhang, Y., Li, M., Yang, S., Li, H., Wang, F. BMP7 antagonizes proliferative vitreoretinopathy through retinal pigment epithelial fibrosis in vivo and in vitro.

Intravitreal decorin preventing proliferative vitreoretinopathy in perforating injuries: a pilot study.

PURPOSE: To determine the short-term safety of human recombinant decorin protein in preventing proliferative vitreoretinopathy (PVR) in perforating injuries. METHODS: This is a prospective, single-center, open-label, interventional case series. Single intravitreal injection of decorin 200 µg (n = 4) or 400 µg (n = 8) was given 48 h after injury. At the tenth day, pars plana vitrectomy was done whenever indicated. Flash electroretinogram (ERG) was done before and 3 months post-injection. We assessed ocular inflammation, ERG changes, and retinal layer integrity by optical coherence tomography (OCT). Systemic and vitreous pharmacokinetics were also evaluated. RESULTS: Twelve patients (12 eyes) with perforating globe injuries (zone III) were included and followed for a median of 6 months. Intravitreal decorin injection was well tolerated with no ocular or systemic safety adverse events. Decorin retinal safety was demonstrated anatomically by intact retinal layer by OCT, and functionally by flash ERG which did not show any significant worsening during the study and the final mean logMAR best-corrected visual acuity (BCVA) which was 1.15 (20/280) and 0.7 (20/100) for groups A and B, respectively, and ≥ 20/200 in 75% of all eyes. Decorin serum and vitreous levels were elevated following trauma, with higher and extended levels following intravitreal injection. CONCLUSIONS: No short-term safety concerns were detected after a single intravitreal injection of decorin in patients with perforating injuries. TRIAL REGISTRATION: ClinicalTrials.gov ID: NCT02865031.

Prophylactic Chorioretinectomy in Open Ocular Trauma: A Series of 36 Eyes.

PURPOSE: The aim of this paper was to report the outcomes of prophylactic chorioretinectomy in open-globe injuries where a foreign body penetrated the choroid or perforated the globe. METHODS: We conducted a retrospective, consecutive, noncomparative, and descriptive study of patients registered in the ocular trauma database between January 2006 and December 2014, who underwent vitrectomy with chorioretinectomy. RESULTS: Thirty-six patients (33 male, 3 female) with a mean age of 40 years and a median of follow-up of 13 months were included. Twenty-one cases had penetrating globe injuries with an intraocular foreign body and 15 cases had perforating globe injuries. A concomitant chorioretinectomy was performed in all eyes, although it was only partial in 8 eyes. At the end of follow-up, proliferative vitreoretinopathy (PVR) rates were 6.5%, anatomical success was 80.6%, and the globe survival rate was 96.8%. CONCLUSION: Prophylactic chorioretinectomy is a surgical procedure that may decrease posttraumatic PVR, thus improving final visual acuity and increasing globe survival rates.

Prophylactic chorioretinectomy for eye injuries with high proliferative-vitreoretinopathy risk.

With its incidence exceeding 60%, proliferative vitreoretinopathy (PVR) remains the most important pathology responsible for loss of vision, even the eyeball, after certain types of severe trauma. In this article, we present results obtained using our novel surgical technique, prophylactic chorioretinectomy (PCR), to prevent the development of PVR. Data on severely injured eyes at high risk for PVR [rupture, posterior laceration, deep-impact intraocular foreign body (IOFB) trauma, perforating injury] were collected prospectively. All eyes underwent vitrectomy (PPV) by PCR within 100 hr of the trauma. Eyes were excluded if they presented with endophthalmitis or if the reconstructive surgery was performed outside this time frame. Forty eyes of 40 consecutive patients were analyzed; full follow-up information was obtained for all of them. The injury was rupture in 27%, penetrating in 15%, (deep-impact) IOFB in 35%, and perforating in 23%. PPV-PCR was performed during primary (wound closure) surgery in 59% of cases. All eyes had at least minimal vitreous hemorrhage, and none had a true posterior vitreous detachment. At the time of PPV, 30% of the eyes had a retinal detachment. Sixteen percent developed PVR, but none from the site of the PCR procedure. In 20%, silicone oil remained in the eye at the last follow-up. The visual acuity improved in 93% of eyes and worsened in none; the improvement was mostly due to surgical clearing of the media opacity. In this subgroup of eyes with severe open-globe trauma, over 60% are expected to develop PVR. PPV/PCR performed within 100 hr reduced the PVR risk significantly, so currently it remains the best option for the surgeon. Clin. Anat. 31:28-38, 2018. © 2017 Wiley Periodicals, Inc.

Substance P prevents development of proliferative vitreoretinopathy in mice by modulating TNF-α.

Purpose: Proliferative vitreoretinopathy (PVR) is an inflammatory fibrotic disease resulting from the inflammatory milieu after retinal detachment, which can prevent retinal healing. This study aimed to elucidate the effect of substance P (SP) on retinal degeneration caused by retinal detachment in vivo and to examine the role of SP in the tumor necrosis factor-alpha (TNF-α)-induced epithelial-mesenchymal transition (EMT) of human RPE cells in vitro. Methods: PVR-like retinal damage was induced by intravitreally injecting dispase into mice, and SP was systemically injected twice a week for 3 weeks. Histological analysis and cytokine profile with enzyme-linked immunosorbent assay (ELISA) were performed. The direct effect of SP on induction of EMT in vitro was studied by adding SP to TNF-α-treated ARPE-19 cells and then evaluating the change in the characteristics of the epithelial and mesenchymal cells. Results: Dispase injection led to a PVR-like retinal condition, demonstrating an inflammatory response with disruption of RPE interaction within 1 week and severe destruction with enfolding within 3 weeks after the dispase injection. The inflammatory environment promoted apoptosis and migration of fibroblast-like cells in the retinal layer, which can cause fibrotic disease, such as PVR. However, SP treatment suppressed early inflammatory responses by reducing TNF-α and elevating interleukin-10 (IL-10), with cell death and the appearance of fibroblastic cells inhibited and the progression of retinal degeneration obviously delayed. Moreover, SP ameliorated TNF-α-induced EMT of the RPE and directly prevented fibrotic change in the RPE. Conclusions: This study revealed that SP can block apoptosis and EMT due to retinal inflammation and inhibit the development of PVR. This effect most likely occurred by modulating the secretion and action of TNF-α..

[Surgical treatment of rhegmatogenous retinal detachments with high risk of proliferative vitreoretinopathy]. / Khirurgicheskoe lechenie regmatogennykh otsloek setchatki s vysokim riskom razvitiia proliferativnoi vitreoretinopatii.

AIM: to analyze the effect of internal limiting membrane (ILM) peeling in patients undergoing 23-gauge pars plana vitrectomy for the treatment of rhegmatogenous retinal detachment (RRD) with a high risk of proliferative vitreoretinopathy (PVR). MATERIAL AND METHODS: This was a prospective consecutive study of 231 eyes of 227 patients. All eyes underwent vitrectomy with silicone oil/gas tamponade for RRD with a high risk of PVR: in 42 eyes the ILM was peeled (group 1) and in the remaining 189 eyes - was not (group 2). The follow-up period was at least 3 months. RESULTS: In group 1, single-surgery anatomic success was achieved in 85.4% and definitive reattachment - in 95.2% of patients. In group 2, single-surgery anatomic success was achieved in 67.2% and definitive reattachment - in 89.4% of patients. None of the patients from group 1, who had their ILM peeled, developed epiretinal membrane. Final BCVA in groups 1 and 2 was 1.2±0.5 logMAR and 1.34±0.82 logMAR respectively (p=0.297). CONCLUSION: ILM peeling during vitrectomy in RRD patients at high risk of PVR provides high primary anatomic success rate.

Vascular endothelial growth factor acts primarily via platelet-derived growth factor receptor α to promote proliferative vitreoretinopathy.

Proliferative vitreoretinopathy (PVR) is a nonneovascular blinding disease and the leading cause for failure in surgical repair of rhegmatogenous retinal detachments. Once formed, PVR is difficult to treat. Hence, there is an acute interest in developing approaches to prevent PVR. Of the many growth factors and cytokines that accumulate in vitreous as PVR develops, neutralizing vascular endothelial growth factor (VEGF) A has recently been found to prevent PVR in at least one animal model. The goal of this study was to test if Food and Drug Administration-approved agents could protect the eye from PVR in multiple animal models and to further investigate the underlying mechanisms. Neutralizing VEGF with aflibercept (VEGF Trap-Eye) safely and effectively protected rabbits from PVR in multiple models of disease. Furthermore, aflibercept reduced the bioactivity of both experimental and clinical PVR vitreous. Finally, although VEGF could promote some PVR-associated cellular responses via VEGF receptors expressed on the retinal pigment epithelial cells that drive this disease, VEGF's major contribution to vitreal bioactivity occurred via platelet-derived growth factor receptor α. Thus, VEGF promotes PVR by a noncanonical ability to engage platelet-derived growth factor receptor α. These findings indicate that VEGF contributes to nonangiogenic diseases and that anti-VEGF-based therapies may be effective on a wider spectrum of diseases than previously appreciated.

Outcome of vitrectomy and chorioretinectomy in perforating eye injuries.

PURPOSE: To evaluate the anatomical and functional results of patients who underwent pars plana vitrectomy for perforating eye injuries as well as to analyze the benefit of the chorioretinectomy procedure. METHODS: Retrospective and descriptive study of 24 eyes of 22 patients with perforating eye injuries operated on at the Centro Hospitalar do Porto between January 2006 and December 2012. RESULTS: An early vitrectomy was accomplished in 67% of the eyes and a delayed vitrectomy in 33% of the eyes. A concomitant chorioretinectomy was carried out in 78%. Final proliferative vitreoretinopathy (PVR) was found in 11%. The anatomical success was 83%. At the final follow-up, 78% had best-corrected visual acuity equal to or superior to 5/200. Of the eyes that underwent early vitrectomy, 58% regained a visual acuity of 40/200 or better, versus 17% of the cases that underwent delayed vitrectomy. CONCLUSION: Early vitrectomy with prophylactic chorioretinectomy seems to be an effective approach to prevent PVR and improve the visual outcome and globe survival in perforating injuries.

Ranibizumab is a potential prophylaxis for proliferative vitreoretinopathy, a nonangiogenic blinding disease.

Proliferative vitreoretinopathy (PVR) exemplifies a disease that is difficult to predict, lacks effective treatment options, and substantially reduces the quality of life of an individual. Surgery to correct a rhegmatogenous retinal detachment fails primarily because of PVR. Likely mediators of PVR are growth factors in vitreous, which stimulate cells within and behind the retina as an inevitable consequence of a breached retina. Three classes of growth factors [vascular endothelial growth factor A (VEGF-A), platelet-derived growth factors (PDGFs), and non-PDGFs (growth factors outside of the PDGF family)] are relevant to PVR pathogenesis because they act on PDGF receptor α, which is required for experimental PVR and is associated with this disease in humans. We discovered that ranibizumab (a clinically approved agent that neutralizes VEGF-A) reduced the bioactivity of vitreous from patients and experimental animals with PVR, and protected rabbits from developing disease. The apparent mechanism of ranibizumab action involved derepressing PDGFs, which, at the concentrations present in PVR vitreous, inhibited non-PDGF-mediated activation of PDGF receptor α. These preclinical findings suggest that available approaches to neutralize VEGF-A are prophylactic for PVR, and that anti-VEGF-based therapies may be effective for managing more than angiogenesis- and edema-driven pathological conditions.

A TGF-ß receptor 1 inhibitor for prevention of proliferative vitreoretinopathy.

This study evaluates the use of the TGF-ß receptor 1 inhibitor LY-364947 (LY) to prevent proliferative vitreoretinopathy (PVR). For the in vitro experiments Human Tenon's Fibroblasts (HTFs) and retinal pigment epithelial (RPE) cells were treated with different concentrations of LY to determine HTF proliferation and RPE transdifferentiation. For in vivo testing 30 rabbits underwent a PVR trauma model. The animals received different concentrations of intravitreally injected LY, with or without vitrectomy. LY treatment reduced HTF proliferation and RPE transdifferentiation in vitro. In vivo intravitreal injection of LY prevented PVR development significantly. This positive effect was also present when LY injection was combined with vitrectomy. Intravitreal injection of LY prevented tractional retinal detachment in 14 out of 15 animals. In conclusion, treatment with the TGF-ß receptor 1 inhibitor LY reduces HTF proliferation and RPE transdifferentiation in vitro and prevents proliferative vitreoretinopathy and subsequent tractional retinal detachment in vivo.

Overexpression p21WAF1/CIP1 in suppressing retinal pigment epithelial cells and progression of proliferative vitreoretinopathy via inhibition CDK2 and cyclin E.

BACKGROUND: P21 is one kind of cyclin-dependent kinase inhibitor that can prevent cells from going through the G1/S phase checkpoint and inhibit cell proliferation. Proliferative vitreoretinopathy (PVR) is a proliferative response in the eye. The aim of this study was to determine whether p21Waf1/Cip1 (p21) suppresses the proliferation and migration of retinal pigment epithelial (RPE) cells in vitro and controls PVR development in vivo. METHODS: Cell cycle analyses and transwell assays were conducted to assess cell proliferation characteristics and the migration ability of RPE cells after transfection with p21. Western blot and reverse-transcription polymerase chain reaction technologies were used to detect the expression of p21, CDK2 and cyclinE in RPE cells and rabbit retinal tissues. The impact of increasing p21 expression on PVR development was conducted by implantation of an adenovirus vector containing rabbit p21 (rAd-p21) in a PVR rabbit model. The prevalence of PVR and retinal detachment was determined by indirect ophthalmoscopy on days 3, 7, 14, and 21 after the injection of rAd-p21 into the vitreous. B scans and hematoxylin-eosin staining were employed to check rabbit retinas on day 21. RESULTS: Cell cycle analyses and transwell assays showed that p21 inhibited the proliferation and migration of RPE cells. Increased expression of p21 was detected in cultured RPE cells and rabbit retinas after transfection with the p21 gene, whereas levels of CDK2 and cyclinE were decreased. The increase in p21 expression effectively suppressed the development of PVR in a rabbit model. CONCLUSIONS: The increase in p21 expression in RPE cells not only inhibits the proliferation and migration of RPE cells in vitro, but also suppresses the development of PVR in vivo, which indicates its therapeutic potential in treating PVR.

Protection from sickle cell retinopathy is associated with elevated HbF levels and hydroxycarbamide use in children.

Elevated foetal haemoglobin (HbF) levels are protective against some manifestations of sickle cell anaemia but the impact on retinopathy is unknown. We report on 123 children with HbSS, 10.6% of whom developed retinopathy. Independent of hydroxycarbamide, children with a HbF <15% had 7.1-fold (95% confidence interval, 1.5-33.6) higher odds of developing retinopathy. In children treated with hydroxycarbamide, those with retinopathy had lower HbF levels compared to children without retinopathy (9% vs. 16%; P = 0.005). We report a protective benefit of elevated HbF regarding retinopathy, and our data suggests induction of HbF with hydroxycarbamide may prevent retinopathy in children.