Proliferative vitreoretinopathy: advances in surgical management

Vitreoschisis-induced vitreous cortex remnants in proliferative vitreoretinopathy: A comprehensive review from basic research to clinical practice

Proliferative vitreoretinopathy (PVR) significantly impacts the prognosis of rhegmatogenous retinal detachment (RRD), one of the most critical and increasing causes of vision loss in the Western world. Despite advancements in surgical instruments and techniques, the failure rate due to PVR remains substantial, necessitating additional surgeries and often leading to unsatisfactory visual outcomes. This comprehensive review explores the role of vitreoschisis-induced vitreous cortex remnants (VCR) as a critical, previously under-recognised factor contributing to PVR. Vitreoschisis, a phenomenon where the inner lamellae of the posterior vitreous cortex detach while the outermost layers remain attached to the retina, creates VCR that may contain hyalocytes and serve as scaffolds for fibrocellular proliferation. These remnants are difficult to visualise without triamcinolone acetonide (TA) staining, leading to their frequent lack of recognition in clinical practice. Moreover, removing VCR can be challenging and time-consuming, often requiring meticulous surgical techniques to avoid retinal damage and ensure complete elimination. This review consolidates insights from basic research and clinical practice, emphasising the importance of complete vitreous removal and effective VCR detection and removal to mitigate PVR risks. It highlights the histopathological and clinical evidence supporting the hypothesis that VCR, containing hyalocytes, play a pivotal role in preretinal membrane formation. The review also discusses epidemiological data, surgical management strategies and potential future directions, including improved visualisation techniques and the development of new surgical tools and methods. This review aims to improve surgical outcomes and reduce the frequency and burden of RRD-related complications by addressing VCR as a critical factor in PVR.

Knockdown of HSPA13 Inhibits TGFβ1-Induced Epithelial-Mesenchymal Transition of RPE by Suppressing the PI3K/Akt Signaling Pathway

Purpose

This study aimed to explore the impact of HSPA13 on epithelial-mesenchymal transition (EMT) in retinal pigment epithelial (RPE) cells and proliferative vitreoretinopathy (PVR) development, along with its associated molecular mechanisms.

Methods

HSPA13 expression was evaluated in epiretinal membranes (ERMs) from patients with PVR using immunohistochemistry. The effects of HSPA13 knockdown on TGFβ1-induced EMT in hESC-RPE cells were studied through quantitative PCR (qPCR), Western blot, and wound healing assays. Intracellular Ca2+ levels were measured using Fluo-8/AM incubation. A rat PVR model was induced by the intravitreal injection of RPE cells combined with platelet-rich plasma (PRP). RNA-seq was applied to study the molecular mechanism of HSPA13 knockdown-mediated EMT inhibition.

Results

HSPA13 was found in human ERMs and its expression increased with TGFβ1 treatment in hESC-RPE cells. Knockdown of HSPA13 inhibited TGFβ1-induced EMT and migration. In the PVR rat model, HSPA13 was expressed in the ERMs and its knockdown in RPE cells reduced the development of PVR. Consistent with these observations, RNA-seq showed a global suppression of TGFβ1-induced EMT and migration by shHSPA13 in RPE cells. Mechanistically, TGFβ1 treatment increased intracellular Ca2+ levels, leading to an upregulation of HSPA13 expression. Downregulation of HSPA13 hindered the phosphorylation of PI3K/Akt in TGFβ1-induced RPE cells.

Conclusions

Our study revealed the involvement of HSPA13 in PVR development, as well as in TGFβ1-induced EMT of RPE through the PI3K/Akt signaling pathway. Targeting HSPA13-related pathways involved in regulating EMT in RPE cells could serve as a novel therapeutic approach for patients with PVR.

ADDITIONAL PNEUMATIC RETINOPEXY IN PATIENTS WITH PERSISTENT RETINAL DETACHMENT AFTER SCLERAL BUCKLING

PURPOSE

To investigate the efficacy, safety, and indications for additional pneumatic retinopexy (PR) in patients with persistent retinal detachment after scleral buckling.

METHODS

This retrospective study included patients who underwent additional PR after scleral buckling for primary rhegmatogenous retinal detachment (n = 78). We defined "inadequate buckle" as retinal detachment persistence because of low buckle height despite accurate buckle placement and "buckle misplacement" as an uncovered tear because of incorrect buckle placement.

RESULTS

The anatomical success rate after additional PR was 52.6%. Development of proliferative vitreoretinopathy Grade B (hazard ratio, 5.73; P < 0.001) and inferior retinal tears (hazard ratio, 2.12; P = 0.040) were significant risk factors for anatomical failure. The most common cause of anatomical failure was proliferative vitreoretinopathy (19 of 37; 51.4%), and epiretinal membrane formation was a common complication after additional PR (22 of 78; 28.2%). The anatomical success rate with additional PR was significantly higher in the inadequate buckle group than in the misplacement group (8 of 9 [88.9%] vs. 1228 [42.9%]; P = 0.023).

CONCLUSION

Development of proliferative vitreoretinopathy Grade B and inferior retinal tears were significantly associated with anatomical failure after additional PR. Additional PR may benefit patients with superior retinal tears or low buckle height and those without proliferative vitreoretinopathy.

Proliferative vitreoretinopathy: an update on the current and emerging treatment options

Proliferative vitreoretinopathy (PVR) remains the main cause of failure in retinal detachment (RD) surgery and a demanding challenge for vitreoretinal surgeons. Despite the large improvements in surgical techniques and a better understanding of PVR pathogenesis in the last years, satisfactory anatomical and visual outcomes have not been provided yet. For this reason, several different adjunctive pharmacological agents have been investigated in combination with surgery. In this review, we analyze the current and emerging adjunctive treatment options for the management of PVR and we discuss their possible clinical application and beneficial role in this subgroup of patients.

Retinotomies and retinectomies: A review of indications, techniques, results, and complications

Retinotomy refers to "cutting" or "incising" the retina, whereas retinectomy denotes "excising" the retina. Retinotomies and retinectomies aid in tackling traction and retinal shortening that persist following membrane dissection and scleral buckling. We performed a literature search using Google Scholar and PubMed, followed by a review of the references procured. All relevant literature was studied in detail and summarized. We discuss the indications of retinotomies and retinectomies for relaxing retinal stiffness, accessing the subretinal space for choroidal neovascular membrane, hemorrhage and abscess clearance, drainage retinotomies to allow retinal flattening, radial retinotomies to release circumferential traction, harvesting free retinal grafts, and prophylactic chorioretinectomies in trauma.

Proliferative Vitreoretinopathy: A Reappraisal

Proliferative vitreoretinopathy (PVR) remains the main cause of failure after retinal detachment (RD) surgery. Despite the development of modern technologies and sophisticated techniques for the management of RD, the growth of fibrocellular membranes within the vitreous cavity and on both sides of the retinal surface, as well as intraretinal fibrosis, can compromise surgical outcomes. Since 1983, when the term PVR was coined by the Retina Society, a lot of knowledge has been obtained about the physiopathology and risk factors of PVR, but, despite the proposal of a lot of therapeutic challenges, surgical skills seem to be the only effective way to manage PVR complications.

Large inferior retinectomies for proliferative vitreoretinopathy in silicone oil-filled eyes

Background

To describe the anatomical and functional outcomes and late complications in patients who developed inferior proliferative vitreoretinopathy (PVR) in silicone oil-filled eyes and who required reoperation with large inferior retinectomy.

Methods

This is a single-center, retrospective, interventional case series analysis. The study involved 18 individuals with tractional retinal re-detachment due to PVR development inferiorly in eyes who had undergone prior pars plana vitrectomy and silicone oil as a tamponade. All patients included in the study underwent secondary surgery with large inferior retinectomy (from 120° to 270°) and silicone oil filling.

Results

The mean follow-up period was 44.0 ± 31.5 (± SD) months (range: 4 to 96 months. The anatomical success, defined as the complete reattachment of the retina until the last follow-up, was observed in 88.9% of the cases. The postoperative visual acuity ranged from 20/100 to hand motion at 60 cm. Only two cases (11.1%) did not achieve anatomical success at the last follow-up due to recurrent PVR and retinal re-detachment (one including hypotony). All of the patients were pseudophakic. The PVR grade, as well as the presence of PVR prior to primary surgery, showed no statistical correlation with BCVA, the extent of retinectomies, and final macular status. There was a statistically significant correlation between "Final BCVA" and "Initial BCVA" (r = 0.654) and between "Final BCVA" and "Extent of Retinectomy" (r = 0.615).

Conclusions

Reoperation in eyes filled with silicone oil may be required when PVR is developed. Secondary surgery in these cases with large inferior retinectomy and silicone oil implantation may reach good anatomical success with low rates of late complications, besides improving visual acuity. A better BCVA at the time of re-RD diagnosis and cases of retinectomies with greater extensions showed a positive correlation with better functional outcomes.

Trial registration Research Ethics Committee of the Suel Abujamra Institute reviewed and approved this study protocol (approval number, 5.404.961).

Supplementary Information

The online version contains supplementary material available at 10.1186/s40942-022-00420-1.

Hyalocytes in proliferative vitreo-retinal diseases

Introduction

Hyalocytes are sentinel macrophages residing within the posterior vitreous cortex anterior to the retinal inner limiting membrane (ILM). Following anomalous PVD and vitreoschisis, hyalocytes contribute to paucicellular (vitreo-macular traction syndrome, macular holes) and hypercellular (macular pucker, proliferative vitreo-retinopathy, proliferative diabetic vitreo-retinopathy) diseases.

Areas covered

Studies of human tissues employing dark-field, phase, and electron microscopy; immunohistochemistry; and in vivo imaging of human hyalocytes.

Expert opinion

Hyalocytes are important in early pathophysiology, stimulating cell migration and proliferation, as well as subsequent membrane contraction and vitreo-retinal traction. Targeting hyalocytes early could mitigate advanced disease. Ultimately, eliminating the role of vitreous and hyalocytes may prevent proliferative vitreo-retinal diseases entirely.

Novel insights into the pathophysiology of proliferative vitreoretinopathy: The role of vitreoschisis-induced vitreous cortex remnants

PURPOSE

We previously hypothesized a causal relationship between vitreoschisis-induced vitreous cortex remnants (VCR) and the development of proliferative vitreoretinopathy (PVR). This study aims to substantiate this association through histopathological analysis of surgical specimens in support of strategies to improve therapeutic outcomes.

METHODS

A descriptive, prospective, non-consecutive case series. Histopathological and immunohistochemical analyses were performed on membranes removed from the peripheral retinal surface during initial vitrectomy for primary rhegmatogenous retinal detachment (RRD) (n = 11) or recurrent retinal detachment (n = 12). The clinical aspect of the membranes ranged from loose-meshed membranes visualized with triamcinolone to more fibrotic membranes stained with trypan blue.

RESULTS

Consistent with the clinical presentation, histopathological analysis revealed membranes with different area characteristics. Paucicellular lamellar collagen-rich areas, suggestive of VCR, appeared to transition to areas of increased cellularity and eventually more fibrotic areas of low cellularity. Five different area characteristics could be identified that seemed to correspond to five histopathological stages in PVR formation, with lamellar VCR collagen acting as an essential precondition: 1. Lamellar collagen, low cellularity (hyalocytes). 2. Lamellar collagen, increased cellularity (hyalocytes, glial cells). 3. Lamellar collagen, high cellularity (macrophages, glial cells, RPE-cells). 4. Early fibrosis, decreased cellularity (myofibroblasts). 5. Fibrosis, low cellularity (myofibroblasts).

CONCLUSION

These findings confirm the role of VCR in preretinal PVR formation posterior to the vitreous base. We propose that the presence of VCR over the retinal surface should be qualified as a risk factor for PVR formation. Detection and adequate removal of VCR may improve the success rate of vitreoretinal surgeries.

miRNA‑124 regulates palmitic acid‑induced epithelial‑mesenchymal transition and cell migration in human retinal pigment epithelial cells by targeting LIN7C

The present study revealed that palmitic acid (PA) treatment induced epithelial-mesenchymal transition (EMT) of retinal pigment epithelial (RPE) cells, which are involved in the progression of proliferative vitreoretinopathy (PVR). ARPE-19 cells were treated with PA followed by miRNA screening and EMT marker detection using qRT-PCR. Then, miR-124 mimic or inhibitor was transfected into ARPE-19 cells to explore the role of miR-124 on the EMT of ARPE-19 cells using transwell assay. The underlying mechanism of miRNA were predicted by bioinformatics method and confirmed by luciferase activity reporter assay. Furthermore, gain-of-function strategy was also used to explore the role of LIN7C in the EMT of ARPE-19 cells. The expression of miRNA or mRNA expression was determined by qRT-PCR and the protein expression was determined using western blot assay. The result presented that PA reduced the expression of E-cadherin/ZO-1 whilst increasing the expression of fibronectin/α-SMA. In addition, PA treatment enhanced the expression of microRNA (miR)-124 in ARPE-19 cells. Overexpression of miR-124 enhanced PA-induced upregulation of E-cadherin and ZO-1 expression and downregulation of fibronectin and α-SMA. Moreover, miR-124 mimic also enhanced the migration of ARPE-19 cells induced by PA treatment. Inversely, miR-124 inhibitor presented opposite effect on PA-induced EMT and cell migration in ARPE-19 cells. Luciferase activity reporter assay confirmed that Lin-7 homolog C (LIN7C) was a direct target of miR-124 in ARPE-19 cells. Overexpression of LIN7C was found to suppress the migration ability and expression of fibronectin and α-SMA, while increasing expression of E-cadherin and ZO-1; miR-124 mimic abrogated the inhibitive effect of LIN7C on the EMT of ARPE-19 cells and PA further enhanced this abolishment. Collectively, these findings suggest that miR-124/LIN7C can modulate EMT and cell migration in RPE cells, which may have therapeutic implications in the management of PVR diseases.

Translational and clinical advancements in management of proliferative vitreoretinopathy

PURPOSE OF REVIEW

Despite advancement in the surgical instrumentation and techniques, proliferative vitreoretinopathy (PVR) remains the most common cause for failure of rhegmatogenous retinal detachment (RRD) repair. This review discusses ongoing translational and clinical advancements in PVR.

RECENT FINDINGS

PVR represents an exaggerated and protracted scarring process that can occur after RRD. The primary cell types involved are retinal pigment epithelium, glial, and inflammatory cells. They interact with growth factors and cytokines derived from the breakdown of the blood-retinal barrier that trigger a cascade of cellular processes, such as epithelial-mesenchymal transition, cell migration, chemotaxis, proliferation, elaboration of basement membrane and collagen and cellular contraction, leading to overt retinal pathology. Although there are currently no medical therapies proven to be effective against PVR in humans, increased understanding of the risks factors and pathophysiology have helped guide investigations for molecular targets of PVR. The leading therapeutic candidates are drugs that mitigate growth factors, inflammation, and proliferation are the leading therapeutic candidates.

SUMMARY

Although multiple molecular targets have been investigated to prevent and treat PVR, none have yet demonstrated substantial evidence of clinical benefit in humans though some show promise. Advancements in our understanding of the pathophysiology of PVR may help develop a multipronged approach for this condition.

Outcomes of Primary Rhegmatogenous Retinal Detachment Repair in Eyes With Preoperative Grade B or C Proliferative Vitreoretinopathy

Purpose:

This work evaluates the anatomic and functional outcomes of primary rhegmatogenous retinal detachments (RRDs) with preoperative grade B and C proliferative vitreoretinopathy (PVR) vs eyes without PVR.

Methods:

As a multi-institutional, interventional, retrospective study of all patients undergoing primary RRD surgical procedures from January 1, 2015, through December 31, 2015, this study evaluated the visual acuity (VA) outcomes and single-surgery anatomic success rates (SSAS) of patients with primary grade B and C PVR at the time of RRD repair.

Results:

A total of 2486 eyes underwent primary RD surgery during the study period, of which 153 eyes (6.2%) had documented preoperative PVR grade B or C. Eyes without PVR had better SSAS compared with eyes with grade B or C PVR (87% vs 83% vs 75%, respectively, P < .0001). Eyes without PVR also had better final mean (SD) logMAR VA (0.35 [0.47]; 20/45 Snellen equivalent) than eyes with PVR of grade B (0.50 [0.56]; 20/63 Snellen equivalent) or grade C ( P < .0001). In only eyes with preoperative PVR, there were no significant differences in final VA or SSAS on multivariate analysis based on surgical approach or use of retinectomy or membrane peeling alone in the intraoperative management of PVR.

Conclusions:

Eyes with primary preoperative grade B and C PVR appear to have significantly worse VA outcomes and lower surgical success rates. Surgical approach and management of PVR membranes did not appear to affect VA or success rates, indicating that preoperative PVR severity may dictate these outcomes.

Factors Associated With Good Visual Acuity Outcomes After Retinectomy in Eyes With Proliferative Vitreoretinopathy

PURPOSE

To investigate factors associated with good visual acuity (VA) following repair of rhegmatogenous retinal detachments (RD) with proliferative vitreoretinopathy (PVR) undergoing retinectomy.

DESIGN

Interventional, retrospective, case-control study.

METHODS

This single-institution study evaluated patients who underwent retinectomy during repair of RD with PVR from January 1, 2015 to December 31, 2019. A good VA cohort was identified based on a final VA ≥20/70. A 2:1 age-matched and gender-matched poor VA cohort with VA <20/70 was subsequently identified. Metrics compared between the two cohorts included time from primary and recurrent RD diagnosis to surgery, lens status, initial RD size, macula involvement, PVR grade, and size of retinectomy.

RESULTS

A total of 5355 eyes were diagnosed with primary RD during the study period, of which 345 had PVR and underwent retinectomy. The good VA cohort included 62 eyes with a mean final logMAR VA of 0.32 [Snellen 20/42], while the poor VA cohort included 119 eyes with a mean final logMAR VA of 1.54 [Snellen 20/693; P < .0001]. On multivariate analysis, smaller initial RD size (P = .0090), fewer surgeries (P = .0002), shorter time between recurrent RD diagnosis and subsequent surgeries (P = .0006), better preoperative VA (P = .0276), and pseudophakia at final visit (P = .0049) remained significant predictors of good vision.

CONCLUSION

Eyes undergoing retinectomy during repair of RD with PVR can achieve good VA outcomes. The primary modifiable factor associated with better VA was shorter delay between redetachment diagnosis and surgery, particularly in the absence of silicone oil tamponade.

Risk factors for epiretinal membrane in eyes with primary rhegmatogenous retinal detachment that received silicone oil tamponade

Background/aims

This study investigated the risk factors for epiretinal membrane (ERM) in eyes with primary rhegmatogenous retinal detachment (RRD) that received silicone oil (SO) tamponade.

Methods

This retrospective analysis included 1140 patients (1140 eyes) with RRD who underwent primary vitrectomy and SO tamponade. The prevalence of ERM was estimated and possible risk factors (eg, type 2 diabetes, proliferative vitreoretinopathy (PVR), SO tamponade time (SOTT), photocoagulation, vitreous haemorrhage, choroidal detachment, cryotherapy and retinal tear size) were analysed via multiple logistic regression.

Results

The prevalence of ERM was 12.3% (140/1140), and the accuracy of preoperative ERM diagnosis was 40.5%. Multivariate logistic regression analysis showed that risk factors for ERM in eyes with SO tamponade included preoperative PVR (OR=4.336, 95% CI 2.533 to 7.424, p<0.001), type 2 diabetes (OR=3.996, 95% CI 2.013 to 7.932, p<0.001), photocoagulation energy (OR=1.785, 95% CI 1.306 to 2.439, p<0.001) and SOTT (OR=1.523, 95% CI 1.261 to 1.840, p<0.001). No statistically significant associations were observed between the incidence of ERM and other risk factors. Preoperative PVR showed the strongest association with risk of ERM. The risk of ERM was positively associated with SOTT, photocoagulation energy and preoperative PVR grade.

Conclusion

In eyes with RRD that received SO tamponade, the prevalence of ERM was 12.3%, while the accuracy of preoperative ERM diagnosis was low. Preoperative PVR, type 2 diabetes, photocoagulation energy and SOTT were the main risk factors for ERM.

Managing PVR in the Era of Small Gauge Surgery

Proliferative vitreoretinopathy (PVR) is the leading cause of failed rhegmatogenous retinal detachment (RRD) surgery. Based upon the presence of clinical features and due to associated underlying risk factors, it is classified into various grades based upon its severity and extent of involvement. Despite excellent skills, flawless techniques, and high-end technology applied in the management of RRD, PVR still occurs in 5–10% of cases. Due to the advancements in wide angle viewing systems, advance vitrectomy machines and fluidics, early identification, use of long-term heavy silicon oil tamponades, high-speed cutters, small-gauge vitrectomies, use of perfluorocarbon liquid (PFCL), and small-gauge forceps and scissors, the success rate in the management of PVR has increased leading to improved anatomical outcomes. However, functional outcomes do not correlate well with improved anatomical outcomes. Various complications occur after RRD repair that are responsible for re-retinal detachment and recurrence of PVR. This article highlights causes, risk factors, classification, grading, diagnosis, and approach to management of PVR and post-PVR surgery complications.

SURGICAL FAILURES AFTER PRIMARY SCLERAL BUCKLING FOR RHEGMATOGENOUS RETINAL DETACHMENT: Comparison of Eyes With and Without Proliferative Vitreoretinopathy

PURPOSE

To compare proliferative vitreoretinopathy (PVR)-related surgical failure and non-PVR-associated failure after scleral buckling for primary rhegmatogenous retinal detachment.

METHODS

In this single-center, retrospective, consecutive case series, eyes with surgical failure after scleral buckling for primary rhegmatogenous retinal detachment were identified. Eyes with surgical failure were categorized as PVR-associated and non-PVR-associated failure, and these groups were compared.

RESULTS

Of the 530 scleral buckling procedures performed, 69 were surgical failures (13%), of which 27 of the 530 (5%) were due to PVR and 42 of the 530 (8%) were from non-PVR causes. Patients with PVR-associated failure were more likely to be smokers (P < 0.001), have a delayed presentation after symptoms (P = 0.011), have preoperative vitreous hemorrhage (P = 0.004), and have preoperative PVR (P = 0.002). Multivariate logistic regression models showed that the odds of PVR-associated failure were greater in eyes with preoperative vitreous hemorrhage (odds ratio, 8.2; P = 0.048), preoperative PVR (odds ratio, 22.7; P = 0.023), and among previous smokers (odds ratio, 28.8; P < 0.001). Thirty-two of 69 patients (46%) required one additional surgical intervention, and 37 of the 69 patients (53%) required two or more additional interventions to achieve final reattachment.

CONCLUSION

Proliferative vitreoretinopathy-related surgical failure after primary scleral buckling was 5%. Risk factors for PVR-associated failure parallel those commonly referenced for pars plan vitrectomy, including smoking history, preoperative vitreous hemorrhage, and preoperative PVR.

The role of vitreous cortex remnants in proliferative vitreoretinopathy formation demonstrated by histopathology: A case report

Purpose

The pathogenesis of proliferative vitreoretinopathy (PVR), the most important cause of retinal detachment surgery failure, is still not fully understood. We previously hypothesized a causal link between vitreoschisis-induced vitreous cortex remnants (VCR) and PVR formation. The purpose of this case report is to demonstrate this association by showing the clinical occurrence of PVR in the presence of VCR across the retinal surface, illustrated by histopathological analysis.

Observations

A 69-year-old male was referred because of widespread epiretinal membrane formation after treatment of recurrent retinal detachments. During surgery with extensive membrane peeling, a large continuous membrane was peeled from the superior arcade towards the inferior temporal mid-periphery. Histopathological analysis of this membrane revealed areas with different characteristics: paucicellular laminar collagen-rich areas, suggestive for VCR, areas with increased cellularity, and more fibrotic areas with low cellularity.

The immunohistochemical analysis identified cell type variety in these areas: collagen-rich areas showed glial cells and hyalocytes, while in areas with high cellularity fibroblasts, macrophages and retinal pigment epithelial cells were found, which have previously been shown to play an important role in the development of PVR as they can transdifferentiate into myofibroblasts, which were seen in the more fibrotic areas.

Conclusions and importance

These findings support the theory that VCR have a role in PVR development, where VCR can act as a scaffold for fibrocellular proliferation. We suggest that the presence of VCR over the retinal surface should be qualified as a risk factor for PVR formation. Detection and adequate removal of VCR may improve the success rate of retinal detachment surgery.

Polarity and epithelial-mesenchymal transition of retinal pigment epithelial cells in proliferative vitreoretinopathy

Under physiological conditions, retinal pigment epithelium (RPE) is a cellular monolayer composed of mitotically quiescent cells. Tight junctions and adherens junctions maintain the polarity of RPE cells, and are required for cellular functions. In proliferative vitreoretinopathy (PVR), upon retinal tear, RPE cells lose cell-cell contact, undergo epithelial-mesenchymal transition (EMT), and ultimately transform into myofibroblasts, leading to the formation of fibrocellular membranes on both surfaces of the detached retina and on the posterior hyaloids, which causes tractional retinal detachment. In PVR, RPE cells are crucial contributors, and multiple signaling pathways, including the SMAD-dependent pathway, Rho pathway, MAPK pathways, Jagged/Notch pathway, and the Wnt/β-catenin pathway are activated. These pathways mediate the EMT of RPE cells, which play a key role in the pathogenesis of PVR. This review summarizes the current body of knowledge on the polarized phenotype of RPE, the role of cell-cell contact, and the molecular mechanisms underlying the RPE EMT in PVR, emphasizing key insights into potential approaches to prevent PVR.

Management of recurrent rhegmatogenous retinal detachment

Rhegmatogenous retinal detachment (RRD) repair is one of the most common vitreoretinal surgeries a surgeon performs. In an ideal scenario, RRD can be repaired with a single surgical intervention; however, despite excellent skill, flawless technique, and the introduction of high-end technology, up to 10% of cases require additional interventions to ultimately repair recurrent detachments. It is thus important to study the outcomes of multiple interventions to understand whether performing repeat vitrectomy on patients with a history of failed surgeries is worthwhile. Thus, recurrent retinal detachment (re-RD) remains a significant challenge for vitreoretinal surgeons as well as the patients considering the economic and the emotional burden of undergoing multiple interventions. The advent of microincision vitrectomy system, perfluorocarbon liquids, and effective intraocular tamponades has opened new doors for managing re-RDs. In this article, we have reviewed and summarized the various causes and approaches for management for optimal anatomical and functional outcomes.

Proliferative Vitreoretinopathy: A Review

Proliferative vitreoretinopathy (PVR) is the most common cause for failure of rhegmatogenous retinal detachment repair and is characterized by the growth and contraction of cellular membranes within the vitreous cavity and on both sides of the retinal surface as well as intraretinal fibrosis. Currently, PVR is thought to be an abnormal wound healing response that is primarily driven by inflammatory, retinal, and RPE cells. At this time, surgery is the only management option for PVR as there is no proven pharmacologic agent for the treatment or prevention of PVR. Laboratory research to better understand PVR pathophysiology and clinical trials of various agents to prevent PVR formation are ongoing.

PDGF-C and PDGF-D in ocular diseases

PDGFs and their receptors are critical regulators of numerous tissues and organs, including the eye. Extensive studies have shown that PDGFs and their receptors play critical roles in many ocular neovascular diseases, such as neovascular age-related macular degeneration, retinopathy of prematurity, and proliferative vitreoretinopathy. In addition, PDGFs and PDGFRs are also important players in ocular diseases involving the degeneration of retinal neuronal and vascular cells, such as glaucoma and retinitis pigmentosa. Due to their critical roles in the pathogenesis of many blinding ocular diseases, the PDGFs and PDGFRs have been considered as important target molecules for the treatment of eye diseases. PDGF-C and PDGF-D are relatively new members of the PDGF family and are potent angiogenic and survival factors. Recent studies have demonstrated their important roles in different types of eye diseases. Thus, modulating PDGF-C and PDGF-D activities may have therapeutic values for the treatment of ocular neovascular and degenerative diseases. This review mainly summarizes the recent advances on PDGF-C and PDGF-D biology in relationship to some major ocular diseases.

Eupatilin prevents H2O2-induced oxidative stress and apoptosis in human retinal pigment epithelial cells

Eupatilin, a pharmacologically active flavone derived from the Artemisia plant species, is known to possess anti-oxidant activity. However, the effects of eupatilin on oxidative stress-induced retinal damage in retinal pigment epithelium (RPE) cells and the potential mechanisms involved have not been explored. Therefore, the aim of this study was to investigate the effects of eupatilin on oxidative stress-induced retinal damage in RPE cells. Our results showed that eupatilin significantly attenuated H₂O₂-induced cell injury and ROS production in ARPE-19 cells. In addition, eupatilin pretreatment greatly upregulated Bcl-2 expression, downregulated Bax expression, as well as suppressed caspase-3 activity in ARPE-19 cells exposed to H₂O₂. Furthermore, eupatilin pretreatment markedly enhanced phosphorylation levels of PI3K and Akt in ARPE-19 cells exposed to H₂O₂. In conclusion, our data showed that eupatilin protected against H₂O₂-induced oxidative stress and apoptosis through the activation of PI3K/Akt signaling pathway in ARPE-19 cells. Thus, eupatilin may be useful for the prevention or treatment of proliferative vitreoretinopathy (PVR).

Combined pars plana vitrectomy-scleral buckle versus pars plana vitrectomy for proliferative vitreoretinopathy

The purpose of the study is to evaluate the surgical outcomes of combined pars plana vitrectomy-scleral buckle (PPV-SB) versus pars plana vitrectomy (PPV) for rhegmatogenous retinal detachment complicated with proliferative vitreoretinopathy (PVR). One thousand one hundred and seventy four patients with rhegmatogenous retinal detachment surgery between January 2002 and December 2013 were retrospectively reviewed. Patients with grade C PVR treated with either combined PPV-SB or PPV alone were included in the study. Study outcomes included single surgery anatomic success rate and postoperative visual outcome at 12 months postoperatively. Seventy-seven patients with grade C PVR were identified for analysis. At the end of 12-month follow-up, 80.5 % eyes (33/41) in the PPV-SB group and 58.3 % eyes (21/36) in the PPV group achieved single surgery anatomical success. In a multiple logistic regression model, none of the baseline variables (age, gender, macula status, grade of PVR, extent of detachment, presence of vitreous hemorrhage, lens status, status of high myopia) nor types of retinal detachment surgery (use of scleral buckle, barrier endolaser, 360 degree endolaser, cryopexy, retinectomy, tamponade agent, phacoemulsification) had significant effect on single surgery anatomical success. The post-treatment mean logMAR visual acuity of the PPV-SB group was 1.58 ± 0.58 and the PPV group was 1.57 ± 0.61. There was no significant difference in the postoperative visual acuity between the two groups (P = 0.849). For patients with grade C PVR, PPV-SB did not demonstrate a superiority over PPV alone in achieving single surgery anatomical success.

Proliferative vitreoretinopathy: A new concept of disease pathogenesis and practical consequences

During the last four decades, proliferative vitreoretinopathy (PVR) has defied the efforts of many researchers to prevent its occurrence or development. Thus, PVR is still the major complication following retinal detachment (RD) surgery and a bottle-neck for advances in cell therapy that require intraocular surgery. In this review we tried to combine basic and clinical knowledge, as an example of translational research, providing new and practical information for clinicians. PVR was defined as the proliferation of cells after RD. This idea was used for classifying PVR and also for designing experimental models used for testing many drugs, none of which were successful in humans. We summarize current information regarding the pathogenic events that follow any RD because this information may be the key for understanding and treating the earliest stages of PVR. A major focus is made on the intraretinal changes derived mainly from retinal glial cell reactivity. These responses can lead to intraretinal PVR, an entity that has not been clearly recognized. Inflammation is one of the major components of PVR, and we describe new genetic biomarkers that have the potential to predict its development. New treatment approaches are analyzed, especially those directed towards neuroprotection, which can also be useful for preventing visual loss after any RD. We also summarize the results of different surgical techniques and clinical information that is oriented toward the identification of high risk patients. Finally, we provide some recommendations for future classification of PVR and for designing comparable protocols for testing new drugs or techniques.