Intravitreal bevacizumab in active progressive proliferative diabetic retinopathy

Association between the response of intravitreal antivascular endothelial growth factor injection and systemic factors of diabetic macular edema

BACKGROUND

This study investigated the effects of systemic factors in response to intravitreal injections in patients with macular edema due to non-proliferative diabetic retinopathy (NPDR).

METHODS

We retrospectively reviewed the medical records of patients treated with intravitreal injections for macular edema secondary to NPDR between January 2018 and January 2021. The patients were divided into three groups according to the injection response. When patients with diabetic macular edema showed 20µ or more reduction in central retinal thickness compared to baseline, they were classified as responsive group, and if not, they were classified as refractory group. The responsive group was further divided into the complete and incomplete response groups. Patients with complete disappearance of edema at seven months were classified as the complete response group, whereas those in which edema did not disappear were classified as the incomplete response group. The clinical characteristics of each group, including medical history, ophthalmic examination results, and laboratory examination results at the time of diagnosis, were analyzed.

RESULTS

Of the 112 eyes (91 patients) that satisfied the inclusion criteria, 89 (77 patients) in the responsive group and 23 (14 patients) in the refractory group were included in the analysis. The responsive group was further divided into the complete (51 eyes) and incomplete (38 eyes) response groups. The refractory group had significantly higher glycated hemoglobin levels and significantly lower estimated glomerular filtration rates than the responsive group (p = 0.026 and p = 0.012, respectively). In the multivariate logistic regression analysis, both factors were found to be significant in predicting the degree of response (all p < 0.05). No factor showed a significant difference between the incomplete and complete response groups(all p > 0.05).

CONCLUSIONS

In macular edema caused by NPDR, low glomerular filtration rates and high glycated hemoglobin levels may be used as predictors of poor response to intravitreal injection therapy. In addition to blood glucose control, education should be provided regarding the need for the continuous monitoring of renal function.

A Paradigm Shift in the Management Approaches of Proliferative Diabetic Retinopathy: Role of Anti-VEGF Therapy

Diabetic retinopathy (DR) is considered one of the leading causes of vision loss globally. It principally causes upregulation of pro-angiogenic, proinflammatory, and vascular permeability factors such as vascular endothelial growth factor (VEGF), leading to neovascularisation. The advanced stage of DR or proliferative diabetic retinopathy (PDR) is of more concern, as it leads to vitreous haemorrhage and traction retinal detachment. Various risk factors associated with PDR include hyperglycemia, hypertension, neuropathy, dyslipidemia, anaemia, nephropathy, and retinal complications of drugs used for diabetes. Current management approaches for PDR have been stratified and involve pan-retinal photocoagulation, vitrectomy, and anti-VEGF agents. Given the emerging role of anti-VEGF agents as a favourable adjunct or alternative therapy, they have a critical role in the management of PDR. The review emphasises current management approaches for PDR focusing on anti-VEGF therapy. The review also highlights the risk/benefit evaluation of the various approaches employed for PDR management in various clinical scenarios.

Favorable Anti-VEGF Crunch Syndrome: Nonsurgical Relief of Vitreoretinal Traction in Eyes With Proliferative Diabetic Retinopathy and Tractional Retinal Detachment

Herein are reported four eyes among three patients with favorable anti-vascular endothelial growth factor crunch syndrome by which contraction of fibrovascular tissue led to relief of vitreoretinal traction without surgical intervention. This phenomenon led to complete or partial retinal reattachment in two patients with diabetic tractional retinal detachments. These cases represent favorable anatomic outcomes of crunch syndrome secondary to anti-vascular endothelial growth factor pharmacotherapy and are unique compared with most cases, which have been associated with negative outcomes. [Ophthalmic Surg Lasers Imaging Retina 2022;53:455-459.].

Angiogenic footprints in diabetic retinopathy: opportunities for drug development

Diabetic retinopathy is one of the withering disorders that has been making the lives of patients miserable. Arising as a result of chronic high blood sugar levels in diabetes patients, retinopathy has become a major reason causing permanent blindness, retinal detachment, vitreous humor, rage, or glaucoma among patients. Angiogenesis being the major culprit behind the development of this condition is the growth of new blood vessels from the earlier ones existing. The abnormal growth and poor development of blood vessels also lead to aggravation of the conditions, with vascular endothelial growth factor (VEGF) playing a major role in the process. Various anti-angiogenic therapies or anti-VEGF therapies are being explored for the treatment of this condition. 4 widely explored drugs being-Bevacizumab, pegaptanib sodium, ranibizumab, and aflibercept. The review article tries to summarize studies illustrating the efficacy of these drugs in the treatment of diabetic retinopathy along with some of the herbal therapeutic paradigms displaying anti-angiogenic action that is being used to treat this condition.

Review of Studies Comparing Panretinal Photocoagulation and Anti-Vascular Endothelial Growth Factor Therapy in the Treatment of Proliferative Diabetic Retinopathy

Diabetic retinopathy (DR) is among the leading causes of blindness at the global level. A review of studies between 2015 and 2018 found that about 1.7% of the general population with any type of diabetes mellitus suffered from proliferative diabetic retinopathy (PDR). Since the 1960s, panretinal photocoagulation (PRP) has been the mainstay of treatment for PDR. During this period, PRP has been credited with a significant degree of success and a relatively low complication rate. However, the advent of anti-vascular endothelial growth factor (anti-VEGF) therapy with the beginning of the new millennium provided a treatment modality that was noninferior to PRP. A decade-long period of comparisons and debates between these two treatment modalities repeatedly favored anti-VEGF over PRP, as studies demonstrated that the former provided potentially superior outcomes to PRP. The aim of this review is to briefly discuss and compare the relevant studies and evidence supporting these two treatments.

Comparison of before versus after intravitreal bevacizumab injection, growth factor levels and fibrotic markers in vitreous samples from patients with proliferative diabetic retinopathy

PURPOSE

In diabetic retinopathy patients, intravitreal bevacizumab (IVB) injections are widely used to facilitate dissection of retinal fibrovascular membranes during surgery, reduce the rate of perioperative hemorrhage, and prevent recurrent neovascularization. Previous studies have shown that IVB may worsen fibrosis and thereby impair vision. The aim of this study was to determine which markers are associated with fibrosis.

METHODS

Twenty-three patients with proliferative diabetic retinopathy (PDR) underwent pars plana vitrectomy (PPV) with IVB pretreatment for intraocular hemorrhage (IOH) and/or tractional retinal detachment (TRD). Vitreous samples were obtained at the time of IVB injection and again at the beginning of PPV, about a week later. Using Western blot analysis, the concentrations of vascular endothelial growth factor (VEGF), placental growth factor (PIGF), insulin like growth factor-1 (IGF-1), angiogenin-1 (Ang-1), and vascular endothelial cadherin (VE-cadherin) were measured in vitreous samples.

RESULTS

After treatment with IVB, VEGF, PIGF, and VE-cadherin concentrations in the vitreous significantly decreased (p < 0.001, p < 0.001, and p = 0.001, respectively), whereas the concentrations of IGF-1 increased (p = 0.001). There were no significant changes in Ang-1 concentrations in the vitreous after IVB injection (p = 0.732). There were no statistically significant differences in VEGF-A, PIGF, VE-cadherin, IGF, and Ang-1 levels before and after IVB injection when the IOH and TRD groups underwent subgroup analysis (p = 0.696, p = 0.516, p = 0.498, p = 0.188, and p = 0.243, respectively).

CONCLUSION

The levels of VEGF and other cytokines changed in the vitreous after IVB. The adverse effects associated with IVB, such as fibrosis, may result from modulation of vitreous cytokine concentrations. In the treatment of PDR, drugs that optimize the effects of PIGF, IGF-1, and VE-cadherin to reduce these side effects may be useful.

Intravitreal bevacizumab prior to vitrectomy for proliferative diabetic retinopathy: a systematic review

Background:

Diabetic retinopathy is a leading cause of visual loss in the working population. Pars plana vitrectomy has become the mainstream treatment option for severe proliferative diabetic retinopathy (PDR) associated with significant vitreous haemorrhage and/or tractional retinal detachment. Despite the advances in surgical equipment, diabetic vitrectomy remains a challenging operation, requiring advanced microsurgical skills, especially in the presence of tractional retinal detachment. Preoperative intravitreal bevacizumab has been widely employed as an adjuvant to ease surgical difficulty and improve postoperative prognosis.Aims: This study aims to assess the effectiveness of preoperative intravitreal bevacizumab in reducing intraoperative complications and improving postoperative outcomes in patients undergoing vitrectomy for the complications of PDR.

Methods:

A literature search was conducted using the PubMed, Cochrane, and ClinicalTrials.gov databases to identify all related studies published before 31/10/2020. Prespecified outcome measures were operation time, intraoperative iatrogenic retinal breaks, best-corrected visual acuity in the last follow-up visit, the presence of any postoperative vitreous haemorrhage and the need to re-operate. Evidence synthesis was performed using Fixed or Random Effects models, depending on the heterogeneity of the included studies. Heterogeneity was assessed using Q-statistic and I². Additional meta-regression models, subgroup analyses and sensitivity analyses were performed as appropriate.

Results:

Thirteen randomized control trials, with a total of 688 eyes were included in this review. Comparison of the intraoperative data showed that bevacizumab reduced operation time (p < 0.001), minimized iatrogenic retinal breaks (p < 0.001), provided better long-term visual acuity outcomes (p = 0.005), and prevented vitreous haemorrhage (p < 0.001) and the need for reoperation (p = 0.001 < 0.05). Findings were strongly corroborated by additional sensitivity and subgroup analyses.

Conclusion:

Preoperative administration of bevacizumab is effective in reducing intraoperative complications and improving the postoperative prognosis of diabetic vitrectomy.

PROSPERO registration number: CRD42021219280

A NEW BIOMARKER QUANTIFYING THE EFFECT OF ANTI-VEGF THERAPY IN EYES WITH PROLIFERATIVE DIABETIC RETINOPATHY ON ULTRA-WIDE FIELD FLUORESCEIN ANGIOGRAPHY: RECOVERY STUDY

PURPOSE

To quantify changes of the retinal vascular bed area (RVBA) in mm2 on stereographically projected ultra-wide field (UWF) fluorescein angiography (FA) images by in eyes with proliferative diabetic retinopathy (PDR) following anti-vascular endothelial growth factor (VEGF) injection.

METHODS

Prospective, observational study. The early-phase UWF FA images (Optos 200Tx) of 40 eyes with PDR and significant non-perfusion obtained at baseline and after 6 months (NCT02863354) were stereographically projected by correcting peripheral distortion. The global retinal vasculature on UWF FA was extracted for calculating RVBA by summing the real size (mm2) of all the pixels automatically.

RESULTS

For the entire cohort, global RVBA for the entire retina decreased from 67.1 ± 15.5 mm2 to 43.6 ± 18.8 mm2 after anti-VEGF treatment at 6 months (P < 0.001). In the sub-group receiving monthly anti-VEGF injections, global RVBA decreased from 68.7 ± 16.2 mm2 to 33.9 ± 13.3 mm2 (P < 0.001). In the sub-group receiving anti-VEGF every 3 months, global RVBA decreased from 65.6 ± 15.1 mm2 to 50.8 ± 19.3 mm2 (P = 0.004).

CONCLUSIONS

RVBA appears to be a new biomarker to indicate efficiency of retinal vascular changes after anti-VEGF injection. Eyes with PDR and significant non-perfusion demonstrate reduced RVBA following anti-VEGF treatment.

NATURAL COURSE OF VITREOMACULAR TRACTION IN EYES WITH DIABETIC RETINOPATHY AND FACTORS ASSOCIATED WITH SPONTANEOUS RELEASE

PURPOSE

The aim of this study was to determine the natural course of vitreomacular traction (VMT) in patients with diabetic retinopathy and to evaluate the factors associated with VMT relief.

METHODS

Seventy-four eyes of 65 patients with VMT accompanying diabetic retinopathy were evaluated retrospectively. The presence of intravitreal injection and the presence of panretinal photocoagulation were obtained from the medical records of the patients. Spontaneous release of VMT, the horizontal length of vitreomacular traction, the presence of hyperreflective retinal spots, the presence of the epiretinal membrane, and the grade of VMT were evaluated from the spectral-domain optical coherence tomography images. Factors associated with the spontaneous release of VMT were evaluated by logistic regression analysis.

RESULTS

Spontaneous release was observed in 28 eyes (37.8%). The horizontal length of VMT was lower in the release of the VMT group compared with the persistent VMT group (P = 0.03). The persistent VMT group had a higher rate of hyperreflective retinal spots and epiretinal membrane compared with the release of the VMT group (respectively; P = 0.003 and P = 0.031). No statistically significant difference was observed between the release of VMT and persistent VMT groups in terms of intravitreal injection and panretinal photocoagulation treatment (respectively; P = 0.938 and P = 0.36). The absence of hyperreflective retinal spots was the most important prognostic factor for the spontaneous release of VMT (P = 0.029).

CONCLUSION

Spontaneous release of VMT observed higher rates of patients without hyperreflective retinal spots, epiretinal membrane, and patients with lower horizontal length of VMT.

Recent trends in drug-delivery systems for the treatment of diabetic retinopathy and associated fibrosis

Diabetic retinopathy is a frequent microvascular complication of diabetes and a major cause of visual impairment. In advanced stages, the abnormal neovascularization can lead to fibrosis and subsequent tractional retinal detachment and blindness. The low bioavailability of the drugs at the target site imposed by the anatomic and physiologic barriers within the eye, requires long term treatments with frequent injections that often compromise patient's compliance and increase the risk of developing more complications. In recent years, much effort has been put towards the development of new drug delivery platforms aiming to enhance their permeation, to prolong their retention time at the target site and to provide a sustained release with reduced toxicity and improved efficacy. This review provides an overview of the etiology and pathophysiology of diabetic retinopathy and current treatments. It addresses the specific challenges associated to the different ocular delivery routes and provides a critical review of the most recent developments made in the drug delivery field.

Targeting RGD-binding integrins as an integrative therapy for diabetic retinopathy and neovascular age-related macular degeneration

Integrins are a class of transmembrane receptors that are involved in a wide range of biological functions. Dysregulation of integrins has been implicated in many pathological processes and consequently, they are attractive therapeutic targets. In the ophthalmology arena, there is extensive evidence suggesting that integrins play an important role in diabetic retinopathy (DR), age-related macular degeneration (AMD), glaucoma, dry eye disease and retinal vein occlusion. For example, there is extensive evidence that arginyl-glycyl-aspartic acid (Arg-Gly-Asp; RGD)-binding integrins are involved in key disease hallmarks of DR and neovascular AMD (nvAMD), specifically inflammation, vascular leakage, angiogenesis and fibrosis. Based on such evidence, drugs that engage integrin-linked pathways have received attention for their potential to block all these vision-threatening pathways. This review focuses on the pathophysiological role that RGD-binding integrins can have in complex multifactorial retinal disorders like DR, diabetic macular edema (DME) and nvAMD, which are leading causes of blindness in developed countries. Special emphasis will be given on how RGD-binding integrins can modulate the intricate molecular pathways and regulate the underlying pathological mechanisms. For instance, the interplay between integrins and key molecular players such as growth factors, cytokines and enzymes will be summarized. In addition, recent clinical advances linked to targeting RGD-binding integrins in the context of DME and nvAMD will be discussed alongside future potential for limiting progression of these diseases.

Anti-VEGF crunch syndrome in proliferative diabetic retinopathy: A review

Anti-vascular endothelial growth factor (anti-VEGF) crunch syndrome describes the progression to tractional retinal detachment following intravitreal anti-VEGF therapy in an eye with proliferative diabetic retinopathy . We reviewed the literature on the anti-VEGF crunch using the PubMed and Cochrane databases. Anti-VEGF crunch typically manifests as sudden vision loss in the affected eye between 1 and 6 weeks following intravitreal anti-VEGF injection, with a mean onset of 13 days. Risk factors for crunch development include the use of a higher anti-VEGF dose and increased severity of diabetic retinopathy with fibrosis. Our review found that intravitreal anti-VEGF, in particular bevacizumab, should be used with caution when treating patients with severe proliferative diabetic retinopathy and pre-existing intraocular fibrosis. In patients where anti-VEGF is used before a planned vitrectomy, we recommend close monitoring for crunch symptoms and proceeding promptly with surgery if there is new or progression of tractional retinal detachment. For eyes with minimal preexisting traction that develop crunch after anti-VEGF treatment, surgeons should proceed to vitrectomy within 7 days. The existing literature on the anti-VEGF crunch is limited by heterogeneity in the way crunch is documented and characterized and the presence of panretinal photocoagulation as a confounding factor. Because of these methodological flaws, the relative frequency of the anti-VEGF crunch cannot be accurately estimated.

Dual-Acting Antiangiogenic Gene Therapy Reduces Inflammation and Regresses Neovascularization in Diabetic Mouse Retina

Intravitreal injections of anti-vascular endothelial growth factor drugs have become the gold standard treatment for diabetic retinopathy (DR). However, several patients are classified as non-responders or poor responders to treatment. Therefore, it is essential to study alternative target molecules. We have previously shown that the progression of DR in the Ins2^Akita mouse reflects the imbalance between pro- and anti-angiogenic molecules found in the human retina. We report, for the first time, the therapeutic potential of a dual-acting antiangiogenic non-viral gene therapy. We have used an expressing vector encoding both the pigment epithelium-derived factor gene and a short hairpin RNA (shRNA) targeted to the placental growth factor to restore the balance between these factors in the retina. Twenty-one days after a single subretinal injection, we observed a marked decrease in the inflammatory response in the neural retina and in the retinal pigment epithelium, together with reduced vascular retinal permeability in the treated diabetic mouse. These results were accompanied by the restoration of the retinal capillary network and regression of neovascularization, with significant improvement of DR hallmarks. Concomitant with the favorable therapeutic effects, this approach did not affect retinal ganglion cells. Hence our results provide evidence toward the use of this approach in DR treatment.

Effect of Intravitreal Bevacizumab Injection before Panretinal Photocoagulation on the Prevention of Macular Edema Aggravation in Proliferative Diabetic Retinopathy

Objective: To investigate the effects of intravitreal bevacizumab (IVB) injection before PRP on the prevention of macular edema (ME) in patients with PDR. Methods: This retrospective observational study included patients diagnosed with PDR treated by PRP with (combination group) or without (PRP alone group) preoperative IVB injection (1.25 mg/0.05 mL). The primary outcome measure was the change in the central macular thickness (CMT), while the secondary outcome measure was the change in visual acuity. Measurements were made before and at one, two, and three months after treatment. Results: In the PRP alone group, the mean baseline CMT of 277.8 μm increased to 290.4 μm at one month (p = 0.201) and 308.8 μm at two months (p = 0.002), followed by a decrease to 271.2 μm at three months (p = 0.437). In the combination group, the values at baseline and one, two, and three months after PRP were 322.9 μm, 295.4 μm (p = 0.002), 330.1 μm (p = 0.906), and 274.5 μm (p = 0.030), respectively. Visual acuity changes were comparable between the two groups at all time points. Conclusion: IVB injection before PRP leads to decreased CMT in comparison to CMT in patients with PRP alone.

Effect of Intrasilicone Bevacizumab Injection in Diabetic Tractional Retinal Detachment Surgery: A Retrospective Case-Control Study

Tractional retinal detachment (TRD) causes visual loss in diabetes mellitus patients. Silicone oil can be used as a tamponade to repair retinal detachment; however, intrasilicone injection is challenging. We aimed to evaluate the effect of intrasilicone bevacizumab injection in TRD surgery. This was a single-hospital, retrospective, case-control study of 44 patients (46 eyes). We reviewed medical histories and ophthalmic examination results. We administered silicone oil to 26 eyes (group I), and a combination of silicone oil and intravitreal bevacizumab injection to 20 eyes (group II). The main outcome measures were the logarithm of the minimum angle of resolution (logMAR) visual acuity and central macular thickness. Mean change in logMAR visual acuity was larger (p = 0.029) in group II (−0.99 ± 0.73) than in group I (−0.56 ± 0.80), 12 months postoperatively. Compared to group I, group II exhibited a lower mean (471.54 ± 120.14 μm vs. 363.40 ± 59.57 µm, respectively; p = 0.001), and mean change (−22.39 ± 203.99 μm vs. −72.40 ± 139.35 µm, respectively; p = 0.027), in central macular thickness, 1 month postoperatively. Intrasilicone bevacizumab injection immediately after vitrectomy may rapidly reduce central macular thickness and increase final visual acuity. Prospective studies are necessary to demonstrate long-term safety and efficacy.

Intravitreal bevacizumab improves the clearance of vitreous haemorrhage and visual outcomes in patients with proliferative diabetic retinopathy

Objective

To evaluate the occurrence of vitreous haemorrhage (VH) secondary to proliferative diabetic retinopathy (PDR) and the efficacy of intravitreal bevacizumab (IVB) for VH in 5-year real-life data.

Methods and analysis

850 adult patients with type 1 (T1D) or type 2 diabetes (T2D) with PDR were screened for VH. The effect of IVB was evaluated by the clearage of VH and the change in best corrected visual acuity (BCVA). The rates of VHs, reinjections, macular oedema, complications, additional treatments and outcomes of spontaneous resorption, panretinal photocoagulation or pars plana vitrectomy (PPV) for VH were also investigated.

Results

VH occurred in 16% of patients with T1D and 9% of patients with T2D with PDR. 336 VHs in 140 eyes of 103 patients were documented. VH was cleared in 92% of cases in less than 3 months by the initial IVB. IVB was superior to other treatment methods in shortening the time for clearance of VH (Kaplan-Meier, p<0.0001). The average rate of IVB reinjections was 1.7±1.1 and the reinjection interval was 7.2±3.9 weeks. BCVA increased 0.73±0.04 logarithm of the minimum angle of resolution units after IVB (generalised estimating equations, p=0.0004). In 5 years, the patients had 2.2±2.7 recurrence of VHs. A simultaneous 72% decrease in the rate of PPVs was documented (p<0.0001).

Conclusion

VH occurs mostly in patients with T1D. The therapeutic effect of IVB for VH was significant and led to improved clearance of VH and visual outcome. Moreover, IVB prevented persistent and recurrent VHs and decreased the need for costly PPV.

Surgical management of diabetic tractional retinal detachments

Tractional retinal detachment is an end-stage form of diabetic retinopathy that occurs when contractile forces in the vitreous and neovascular tissue lead to the detachment of the neurosensory retina. We review the literature related to the management of this disease. Preoperative planning includes appropriate patient selection, diagnostic and prognostic imaging, and medical optimization with reduction of systemic risk factors. Use of antivascular endothelial growth factor for preoperative treatment has had significant benefits for tractional retinal detachment repair in improving surgical efficiency and outcomes. Advances in microsurgical instrumentation are discussed, with attention to small-gauge vitrectomy with improved flow dynamics, viewing strategies, and lighting allowing bimanual surgery. Special emphasis is placed on bimanual surgical technique, choice of tamponade, and the avoidance of iatrogenic damage. Complications and special considerations are further explored. Based on our compilation of relevant literature, we propose a surgical algorithm for the management of these complex patients.

Treatment of Coats' disease: an analysis of pooled results

AIM

To elucidate the association of treatment modality to vitreoretinal fibrosis and traction retinal detachment (TRD) in Coats' disease.

METHODS

A PubMed search for Coats' disease with included studies describing eyes with clinical features and treatment course of Coats' disease. Binary logistic regression with fibrosis at presentation and treatment type as independent variables was performed to determine predictors of TRD historically (since 1921) and in the anti-vascular endothelial growth factor (VEGF) era (since 2007). Odds ratios (OR) with 95% confidence intervals (CI) reported.

RESULTS

Of 175 articles described 1183 eyes. Vitreoretinal fibrosis increased from presentation (5.4%) to follow-up (15.5%) and TRD increased from 0.44% to 3.9% at follow up. Laser was protective against vitreoretinal fibrosis (OR 0.6, 95%CI 0.4-0.9) but TRD was borderline (OR 0.6, 95%CI 0.3-1.1). Cryotherapy showed a higher association with TRD (OR 1.9, 95%CI 1.0-3.7) than with vitreoretinal fibrosis (OR 0.8, 95%CI 0.5-1.2). Similarly, intravitreal anti-VEGF alone was not associated with fibrosis (OR 1.1, 95%CI 0.6-1.8) nor TRD (OR 1.1, 95%CI 0.5-2.6) but the combination of laser and anti-VEGF therapy was protective [Fibrosis: 0.1 (0.03, 0.35); TRD: 0.05 (0.01, 0.23)] compared to anti-VEGF plus cryotherapy (P<0.001). Disease stage ≤2B or ≥3A was not associated with TRD.

CONCLUSION

Vitreoretinal fibrosis and TRD increase after treatment in Coats' disease. The combination of anti-VEGF agents and cryotherapy may lead to higher risk for TRD. Presence of pre-treatment fibrosis is the highest risk factor for post-treatment worsening of vitreoretinal fibrosis and TRD.

Safety and efficacy of intravitreal conbercept injection after vitrectomy for the treatment of proliferative diabetic retinopathy

BACKGROUND/OBJECTIVES

The aim of this study was to evaluate the safety and efficacy of intravitreal conbercept (a recombinant fusion protein that primarily targets vascular endothelial growth factors) after vitrectomy for the management of proliferative diabetic retinopathy without tractional retinal detachment (TRD).

SUBJECTS/METHODS

Fifty patients with non-clearing vitreous haemorrhage (VH) due to proliferative diabetic retinopathy without TRD were enroled. They were randomly divided into control and treatment groups (25 eyes to each group) after they provided informed consent. The treatment group received intravitreal conbercept (10 mg/mL, 0.5 mg) immediately after surgery, while the control group did not. The best corrected visual acuity (BCVA) and the central retinal thickness were measured.

RESULTS

There were no significant between-group differences in baseline characteristics (P > 0.05), except in age (P = 0.003). Improvement in BCVA was significantly greater at 1, 4, 12, and 24 weeks post surgery in the treatment group than it was in the control group (P < 0.001). There were more cases in the control group who developed recurrent VH, but the recurrence rate of VH was not significantly different between the two groups at 12 and 24 weeks post surgery (P = 0.192 and  0.103). Central retinal thickness was lower in the treatment group than in the control group at 1 week (P = 0.012), 4 weeks (P = 0.01), 12 weeks (P = 0.001), and 24 weeks (P = 0.004) post surgery, which were statistically significant.

CONCLUSIONS

An intravitreal injection of conbercept after vitrectomy improved visual acuity and seemed to reduce the recurrence of VH resulting in prompt visual recovery in the PDR patients.

Vitreous concentrations of vascular endothelial growth factor as a potential biomarker for postoperative complications following pars plana vitrectomy

INTRODUCTION

The aim of the study was to investigate the effects of vascular endothelial growth factor (VEGF) concentration in vitreous on postoperative complications after pars plana vitrectomy (PPV).

MATERIAL AND METHODS

Ninety subjects were surgically treated with PPV and followed up for 12 months at the Clinical Centre University Sarajevo, Clinic for Eye Disease. Exclusion criteria were presence of other eye diseases, systemic acute/chronic inflammatory conditions, or malignant neoplasms; previously performed PPV surgery; previously received intravitreal or systemic anti-VEGF therapy. A vitreous sample was obtained while performing the PPV procedure, using the Quantikine ELISA test to determine VEGF level, as a risk factor. Outcome measures were intraoperative and postoperative complications reported using categorical data: blunt and sharp dissection of membranes, intraoperative hemorrhage stopped by increasing infusion pressure, pressing with blunt instrument, or using diathermy. The following postoperative complications were assessed on the first day and at the 12-month follow-up visit: vitreous hemorrhage, fibrovascular proliferation (FVP), rubeosis iridis, and neovascular glaucoma (NVG).

RESULTS

Levels of vitreous VEGF at the time of PPV were significantly higher in eyes with: vitreous hemorrhage on the first day after PPV (p = 0.003); FVP on the first day and 12 months after PPV (p = 0.002 and p < 0.001, respectively); iris rubeosis on the first day and 12 months after PPV surgery (p < 0.001, and p = 0.001, respectively); NVG on the first day and 12 months after PPV surgery (p = 0.043 and p = 0.011, respectively), compared to the eyes without complications.

CONCLUSIONS

Preoperative levels of VEGF in vitreous can be a useful biomarker and predictor of the postoperative outcome in terms of intraoperative and postoperative complications.

Current management of diabetic tractional retinal detachments

Twenty-five percent of diabetes-related vision loss stems from complications of proliferative diabetic retinopathy (PDR). Panretinal photocoagulation has been the preferred treatment of high-risk PDR for decades and more recently intravitreal injections of drugs that inhibit the actions of vascular endothelial growth factor have become popular. But despite these treatments PDR may progress uncontrollably to advanced pathologies such as traction retinal detachments (TRDs), combined traction/rhegmatogenous retinal detachments (TRD/RRDs), vitreous hemorrhages, rubeosis iridis, and traction maculopathies, which produce mild-to-severe loss of vision. TDR have long been the most common indication for PDR-related vitreoretinal surgery. Vitrectomy surgery is indicated for recent (<6 months duration) TRD involving the macula, progressive TRD that threatens the macula, and recent data suggest that chronic macula-involving TRDs (>6 months duration) may also benefit. Combined TRD/RRD represents a particularly challenging surgical condition but advances in surgical instrumentation, dissection techniques, and post-operative tamponade have produced excellent success rates. The recent development of small-gauge vitrectomy systems has persuaded most surgeons to switch platforms since these appear to produce shorter surgical times and quicker post-operative recoveries. Pre-operative injections of bevacizumab are frequently administered for persistent neovascularization to facilitate surgical dissection of pre-retinal fibrosis and reduce the incidence of post-operative hemorrhages. Recent trends toward earlier surgical intervention and expanded indications are likely to continue as surgical instrumentation and techniques are further developed.

Timing of neovascular regression in eyes with high-risk proliferative diabetic retinopathy without macular edema treated initially with intravitreous bevacizumab

Purpose

To determine the timing of neovascular regression after intravitreous injection of bevacizumab (Avastin^®) 1.25 mg given as initial therapy for eyes with high-risk proliferative diabetic retinopathy (PDR) without clinically significant macular edema (CSME).

Patients and methods

In this prospective uncontrolled interventional study, eyes with high-risk PDR without CSME were treated initially with intravitreous injections of bevacizumab 1.25 mg given every 4 weeks until no neovessels were detected, followed by standard pan-retinal photocoagulation (PRP). Patients were examined 48 hours, 1, 2, and 4 weeks after each injection to determine the status of neovascularization.

Results

Twenty-one patients (24 eyes) were included in the study. Forty-eight hours after the first injection of bevacizumab, we observed complete neovascular regression in 20 (83%) eyes. Neovascular regression was maintained in the same number of eyes in the first 2 weeks. At 4 weeks, three eyes displayed neovascular recurrence, and a second injection of bevacizumab was given to the seven eyes with persistent or recurrent neovascularization. Complete neovascular regression was observed in six (86%) eyes after 48 hours and was maintained for 2 weeks following the second bevacizumab injection. Two eyes required a third injection and had complete neovascular regression when assessed after 48 hours and 4 weeks.

Conclusion

The majority of neovessels completely regressed within 48 hours after intra-vitreous injection of bevacizumab given as initial therapy for high-risk PDR without CSME. The full neovascular regressive effect occurred within 48 hours and was maintained for at least 2 weeks.

Sequence effect in the treatment of proliferative diabetic retinopathy with intravitreal ranibizumab and panretinal photocoagulation

PURPOSE

To compare the outcome of the sequence in the two treatments (intravitreal ranibizumab and panretinal photocoagulation) in high-risk proliferative diabetic retinopathy.

METHODS

This retrospective study included 35 patients with newly diagnosed high-risk proliferative diabetic retinopathy in 43 eyes; 18 (22 eyes) received intravitreal ranibizumab before panretinal photocoagulation (intravitreal ranibizumab+ group), while the other 17 (21 eyes) received panretinal photocoagulation before intravitreal ranibizumab (panretinal photocoagulation+ group). Each subject received three intravitreal ranibizumabs that were interleaved with three panretinal photocoagulations. The first treatment (either intravitreal ranibizumab or panretinal photocoagulation) was done 1 week before the second one. The interval between intravitreal ranibizumabs was 4 weeks, panretinal photocoagulation was 2 weeks. The power and pulse duration were determined based upon the status of each retinal spot before each panretinal photocoagulation. The retinal non-perfusion region was measured with fundus fluorescein angiography before and 1 month after the final treatment. The central macular thickness was measured with optical coherence tomography within 1 week before the first treatment, before each panretinal photocoagulation, and 1 month after the final intravitreal ranibizumab.

RESULTS

The panretinal photocoagulation energy required for effective treatment was lower in intravitreal ranibizumab+ group in the first and second sessions and in total energy (p < 0.05). Central macular thickness reduction before the second panretinal photocoagulation session was significant in the intravitreal ranibizumab+ group (p < 0.05).

CONCLUSION

The sequence used in intravitreal ranibizumab+ group showed clear advantages over that in panretinal photocoagulation+ group in the treatment of proliferative diabetic retinopathy, not only in the use of lower energy for panretinal photocoagulation but also in the more rapid regression of neovascularization and less need of additional treatment.

The role of placental growth factor (PlGF) and its receptor system in retinal vascular diseases

Placental growth factor (PlGF) is a member of the vascular endothelial growth factor (VEGF) family. Upon binding to VEGF- and neuropilin-receptor sub-types, PlGF modulates a range of neural, glial and vascular cell responses that are distinct from VEGF-A. As PlGF expression is selectively associated with pathological angiogenesis and inflammation, its blockade does not affect the healthy vasculature. PlGF actions have been extensively described in tumor biology but more recently there has been accumulating preclinical evidence that indicates that this growth factor could have an important role in retinal diseases. High levels of PlGF have been found in aqueous humor, vitreous and/or retina of patients exhibiting retinopathies, especially those with diabetic retinopathy (DR) and neovascular age-related macular degeneration (nvAMD). Expression of this growth factor seems to correlate closely with many of the key pathogenic features of early and late retinopathy in preclinical models. For example, studies using genetic modification and/or pharmacological treatment to block PlGF in the laser-induced choroidal neovascularization (CNV) model, oxygen-induced retinopathy model, as well as various murine diabetic models, have shown that PlGF deletion or inhibition can reduce neovascularization, retinal leakage, inflammation and gliosis, without affecting vascular development or inducing neuronal degeneration. Moreover, an inhibitory effect of PlGF blockade on retinal scarring in the mouse CNV model has also been recently demonstrated and was found to be unique for PlGF inhibition, as compared to various VEGF inhibition strategies. Together, these preclinical results suggest that anti-PlGF therapy might have advantages over anti-VEGF treatment, and that it may have clinical applications as a standalone treatment or in combination with anti-VEGF. Additional clinical studies are clearly needed to further elucidate the role of PlGF and its potential as a therapeutic target in ocular diseases.

Anti-angiogenic effects of valproic acid in a mouse model of oxygen-induced retinopathy

Pathological retinal angiogenesis contributes to the pathogenesis of several ocular diseases. Valproic acid, a widely used antiepileptic drug, exerts anti-angiogenic effects by inhibiting histone deacetylase (HDAC). Herein, we investigated the effects of valproic acid and vorinostat, a HDAC inhibitor, on pathological retinal angiogenesis in mice with oxygen-induced retinopathy (OIR). OIR was induced in neonatal mice by exposure to 80% oxygen from postnatal day (P) 7 to P10 and to atmospheric oxygen from P10 to P15. Mice were subcutaneously injected with valproic acid, vorinostat, or vehicle once a day from P10 to P14. At P15, retinal neovascular tufts and vascular growth in the central avascular zone were observed in mice with OIR. Additionally, immunoreactivity for phosphorylated ribosomal protein S6 (pS6), an indicator of mammalian target of rapamycin (mTOR) activity, was detected in the neovascular tufts. Both valproic acid and vorinostat reduced the formation of retinal neovascular tuft without affecting vascular growth in the central avascular zone. Valproic acid reduced the pS6 immunoreactivity in neovascular tufts. Given that vascular endothelial growth factor (VEGF) activates mTOR-dependent pathways in proliferating endothelial cells of the neonatal mouse retina, these results suggest that valproic acid suppresses pathological retinal angiogenesis by interrupting VEGF-mTOR pathways.

Effect of intravitreal conbercept treatment before vitrectomy in proliferative diabetic retinopathy

AIM

To evaluate the safety and efficacy of intravitreal conbercept (IVC) injections as pretreatment for pars plana vitrectomy (PPV) in severe proliferative diabetic retinopathy (PDR).

METHODS

This was a retrospective chart review of all patients who underwent PPV for PDR from January 2014 to October 2016. Patients who underwent IVC injection before PPV were assigned to the IVC group; the others were assigned to the control group. The IVC was performed 3-7d before surgery in the IVC group. All the eyes in the two groups were operated by the same doctor to complete the vitrectomy. Intraoperative complications and the changes in best-corrected visual acuity (BCVA) before and after surgery were compared between the two groups.

RESULTS

A total of 68 eyes of 63 patients (22 eyes in the IVC group and 46 eyes in the control group) were examined. The risk of intraoperative bleeding was lower in the IVC group (2/22) than in the control group (25/46, P=0.000). Furthermore, the use of endodiathermy was significantly lower in the IVC group (1/22) than in the control group (12/46, P=0.047). The surgical time in the IVC group (112.64±34.52min) was significantly shorter than in the control group (132.85±40.04min, P<0.05). Compared to the BCVA before surgery, the mean BCVA was significantly improved after surgery for both groups (P<0.05).

CONCLUSION

PPV is an effective treatment and can improve vision in patients with PDR. Preoperative intravitreal injection of conbercept could reduce the chances of intraoperative bleeding and the use of endodiathermy and shorten the operative time, which are beneficial in the management of PDR.

Mammalian Target of Rapamycin (mTOR) as a Potential Therapeutic Target in Pathological Ocular Angiogenesis

Pathological ocular angiogenesis is a causative factor of retinopathy of prematurity, proliferative diabetic retinopathy, and wet age-related macular degeneration. Vascular endothelial growth factor (VEGF) plays an important role in pathological angiogenesis, and anti-VEGF agents have been used to treat the ocular diseases that are driven by pathological angiogenesis. However, adverse effects associated with the blockade of VEGF signaling, including impairments of normal retinal vascular growth and retinal function, were suggested. Therefore, the development of a safe, effective strategy to prevent pathological ocular angiogenesis is needed. Recent studies have demonstrated that inhibitors of the mammalian target of rapamycin (mTOR) target proliferating endothelial cells within the retinal vasculature. Here, we review the potential of targeting the mTOR pathway to treat pathological ocular angiogenesis.

Intravitreal Injection of Anti-vascular Endothelial Growth Factor Agents for Ocular Vascular Diseases: Clinical Practice Guideline

PURPOSE

To provide the clinical recommendations for the administration of intravitreal anti-vascular endothelial growth factor (VEGF) drugs especially bavacizumab for ocular vascular diseases including diabetic macular edema, neovascular age-related macular degeneration, myopic choroidal neovascularization, retinal vein occlusion and central serous chorioretinopathy.

METHODS

Twenty clinical questions were developed by the guideline technical committee. Relevant websites and databases were searched to find out the pertinent clinical practice guidelines to answer the questions. The technical committee provided possible answers (scenarios) according to the available evidences for each question. All scenarios along with their levels of evidence and the supported articles were sent to the experts for external review. If the experts did not agree on any of the scenarios for one particular clinical question, the technical committee reviewed all scenarios and their pertinent evidences and made the necessary decision. After that, the experts were asked to score them again. All confirmed scenarios were gathered as the final recommendations.

RESULTS

All the experts agreed on at least one of the scenarios. The technical committee extracted the agreed scenario for each clinical question as the final recommendation. Finally, 56 recommendations were developed for the procedure of intravitreal anti-VEGF injection and their applications in the management of ocular vascular diseases.

CONCLUSION

The implementation of this guideline can standardize the management of the common ocular vascular diseases by intravitreal injection of anti-VEGF agents. It can lead to better policy-making and evidence-based clinical decision by ophthalmologists and optimal evidence based eye care for patients.

Complications of Intravitreous Injections in Patients with Diabetes

Intravitreous injections are presently the second most frequently performed ophthalmic procedure and the most common vitreoretinal procedure. In diabetic patients, intravitreous injections are frequently performed for the treatment of center-involved diabetic macular edema, proliferative diabetic retinopathy, or other co-existing retinal vascular disease. Diabetic patients may be at higher risk of adverse events compared to non-diabetic individuals, given frequent systemic comorbidities, such as cardiovascular and renal disease and increased susceptibility to infection. This review highlights the potential complications and safety considerations in intravitreous injections in patients with diabetes.

Neutralization of placental growth factor as a novel treatment option in diabetic retinopathy

The current standard of care in clinical practice for diabetic retinopathy (DR), anti-vascular endothelial growth factor (VEGF) therapy, has shown a significant improvement in visual acuity. However, treatment response can be variable and might be associated with potential side effects. This study was designed to investigate inhibition of placental growth factor (PlGF) as a possible alternative therapy for DR. The effect of the anti-PlGF antibody (PL5D11D4) was preclinically evaluated in various animal models by investigating different DR hallmarks, including inflammation, neurodegeneration, vascular leakage and fibrosis. The in vivo efficacy was tested in diabetic streptozotocin (STZ) and Akimba models and in the laser induced choroidal neovascularization (CNV) mouse model. Intravitreal (IVT) administration of the anti-PlGF antibody was compared to anti-VEGFR-2 antibody (DC101), anti-VEGF antibody (B20), VEGF-Trap (aflibercept) and triamcinolone acetonide (TAAC). Vascular leakage was investigated in the mouse STZ model by fluorescein isothiocyanate labeled bovine serum albumin (FITC-BSA) perfusion and in the Akimba model by fluorescein angiography (FA). Repeated IVT administration of the anti-PlGF antibody reduced vascular leakage, which was comparable to a single administration of VEGFR-2 inhibition in the mouse STZ model. PL5D11D4 treatment did not alter retinal ganglion cell (RGC) density, as demonstrated by Brn3a staining, whereas DC101 significantly reduced RGC number with 20%. Immunohistological stainings were performed to investigate inflammation (CD45, F4/80) and fibrosis (collagen type 1a). In the CNV model, IVT injection(s) of PL5D11D4 dose-dependently reduced inflammation and fibrosis, as compared to PBS treatment. Equimolar single administration of the anti-PlGF antibody and aflibercept (21 nM) and TAAC decreased leukocyte and macrophage infiltration with 50%, whereas DC101 and B20 (21 nM) had no effect on the inflammatory response. Similar results were observed in the mouse STZ model on the number of microglia and macrophages in the retina. Repeated administration of PL5D11D4 (21 nM) and TAAC similarly reduced fibrosis, while no effect was observed after equimolar DC101, B20 nor aflibercept administration (21 nM). In summary, the anti-PlGF antibody showed comparable efficacy as well-characterized VEGF-inhibitor on the process of vascular leakage, but differentiates itself by also reducing inflammation and fibrosis, without triggering a neurodegenerative response.

INTRAVITREAL BEVACIZUMAB FOR PROLIFERATIVE DIABETIC RETINOPATHY: Results From the Pan-American Collaborative Retina Study Group (PACORES) at 24 Months of Follow-up

PURPOSE

To evaluate the effects of intravitreal bevacizumab (IVB) on retinal neovascularization in patients with proliferative diabetic retinopathy (PDR).

METHODS

Retrospective multicenter interventional case series. A chart review was performed of 81 consecutive patients (97 eyes) with retinal neovascularization due to PDR, who received at least 1 IVB injection.

RESULTS

The mean age of the patients was 55.6 ± 11.6 years. The mean number of IVB injections was 4 ± 2.5 injections (range, 1-8 injections) per eye. The mean interval between IVB applications was 3 ± 7 months. The mean duration of follow-up was 29.6 ± 2 months (range, 24-30 months). Best-corrected visual acuity and optical coherence tomography improved statistically significantly (P < 0.0001, both comparisons). Three eyes without previous panretinal photocoagulation ("naive" eyes) and with vitreous hemorrhage did not require vitreoretinal surgery. Five (5.2%) eyes with PDR progressed to tractional retinal detachment requiring vitrectomy. No systemic adverse events were noted.

CONCLUSION

Intravitreal bevacizumab resulted in marked regression of retinal neovascularization in patients with PDR and previous panretinal photocoagulation. Intravitreal bevacizumab in naive eyes resulted in control or regression of 42.1% of eyes without adjunctive laser or vitrectomy during 24 months of follow-up. There were no safety concerns during the 2 years of follow-up of IVB for PDR.

The incidence and risk factors for the development of vitreomacular interface abnormality in diabetic macular edema treated with intravitreal injection of anti-VEGF

PurposeTo report the incidence and associated factors for the development of vitreomacular interface abnormality (VMIA) in patients with diabetic macular edema (DME) who received intravitreal injection (IVI) of anti-VEGF (Bevacizumab and Ranibizumab) treatment.MethodsA retrospective observational study. Patients with DME followed at least 6 months were reviewed. Baseline best-corrected visual acuity (BCVA), central retinal thickness (CRT) and final BCVA, CRT in eyes with and without VMIA were compared. Multiple logistic regression was also used to investigate the risk factors of VMIA formation in patients with DME treated by anti-VEGF.ResultsA total of 201 eyes in 142 patients met the inclusion criteria of the study. VMIA developed in 44 eyes (21.89%) of patients during a mean follow-up period of 40.84 months. The estimated mean incidence of VMIA formation was 6.43% per year. Poor baseline BCVA was found to be a risk factor for VMIA development (P=0.001, odds ratio=5.299, 95% confidence interval: 1.972 to 14.238). There was no difference between eyes with and without VMIA formation in improving BCVA (P=0.557) and lowering the macular edema (eyes without VMIA formation: -107.72±171.91 μm; eyes with VMIA formation: -155.02±212.27 μm, P=0.133).ConclusionsThis study revealed the incidence of VMIA formation in IVI anti-VEGF treated DME eyes was 6.43%. Poor baseline BCVA was found to be a risk factor for VMIA formation. Both eyes with and without VMIA development had favorable response to anti-VEGF treatment.

Evidence-Based Treatment of Diabetic Retinopathy

Diabetic retinopathy (DR) is the most frequent microvascular complication from diabetes and requires annual screening and at least annual follow-up. A systemic approach to optimize blood glucose and blood pressure may halt progression to severe stages of DR and obviate the need for ocular treatment. Although there is evidence of benefit from fenofibrate or intravitreous antiVEGF treatment for eyes with nonproliferative DR (NPDR), these therapies are not standard care for NPDR at this time. Some patients with severe NPDR, especially those with type 2 diabetes, benefit from early panretinal photocoagulation (PRP). Once DR progresses to proliferative DR (PDR), treatment is often necessary to prevent visual loss. PRP remains mainstay treatment for PDR with high-risk characteristics. However, intravitreous antiVEGF injections appear to be a safe and effective treatment alternative for PDR through at least two years. Vitreoretinal surgery is indicated for PDR cases with non-clearing vitreous hemorrhage and/or tractional retinal detachment.

Diabetic Retinopathy Clinical Practice Guidelines: Customized for Iranian Population

PURPOSE

To customize clinical practice guidelines (CPGs) for management of diabetic retinopathy (DR) in the Iranian population.

METHODS

Three DR CPGs (The Royal College of Ophthalmologists 2013, American Academy of Ophthalmology [Preferred Practice Pattern 2012], and Australian Diabetes Society 2008) were selected from the literature using the AGREE tool. Clinical questions were designed and summarized into four tables by the customization team. The components of the clinical questions along with pertinent recommendations extracted from the above-mentioned CPGs; details of the supporting articles and their levels of evidence; clinical recommendations considering clinical benefits, cost and side effects; and revised recommendations based on customization capability (applicability, acceptability, external validity) were recorded in 4 tables, respectively. Customized recommendations were sent to the faculty members of all universities across the country to score the recommendations from 1 to 9.

RESULTS

Agreed recommendations were accepted as the final recommendations while the non-agreed ones were approved after revision. Eventually, 29 customized recommendations under three major categories consisting of screening, diagnosis and treatment of DR were developed along with their sources and levels of evidence.

CONCLUSION

This customized CPGs for management of DR can be used to standardize the referral pathway, diagnosis and treatment of patients with diabetic retinopathy.

Lack of R-Ras Leads to Increased Vascular Permeability in Ischemic Retinopathy

Purpose

The role of R-Ras in retinal angiogenesis and vascular permeability was evaluated in an oxygen-induced retinopathy (OIR) model using R-Ras knockout (KO) mice and in human diabetic neovascular membranes.

Methods

Mice deficient for R-Ras and their wild-type (WT) littermates were subjected to 75% oxygen from postnatal day 7 (P7) to P12 and then returned to room air. At P17 retinal vascularization was examined from whole mounts, and retinal vascular permeability was studied using Miles assay. Real-time RT-PCR, Western blotting, and immunohistochemistry were used to assess the expression of R-Ras in retina during development or in the OIR model. The degree of pericyte coverage and vascular endothelial (VE)-cadherin expression on WT and R-Ras KO retinal blood vessels was quantified using confocal microscopy. The correlation of R-Ras with vascular endothelial growth factor receptor 2 (VEGFR2) and human serum albumin on human proliferative diabetic retinopathy membranes was assessed using immunohistochemistry.

Results

In retina, R-Ras expression was mostly restricted to the vasculature. Retinal vessels in the R-Ras KO mice were significantly more permeable than WT controls in the OIR model. A significant reduction in the direct physical contact between pericytes and blood vessel endothelium as well as reduced VE-cadherin immunostaining was found in R-Ras–deficient mice. In human proliferative diabetic retinopathy neovascular membranes, R-Ras expression negatively correlated with increased vascular leakage and expression of VEGFR2, a marker of blood vessel immaturity.

Conclusions

Our results suggest that R-Ras has a role in controlling retinal vessel maturation and stabilization in ischemic retinopathy and provides a potential target for pharmacologic manipulation to treat diabetic retinopathy.

ANTI-VASCULAR ENDOTHELIAL GROWTH FACTOR THERAPY FOR PROLIFERATIVE DIABETIC RETINOPATHY: A Systematic Review and Meta-Analysis

PURPOSE

To systematically review and perform meta-analysis on the available randomized controlled trial data for anti-vascular endothelial growth factor (anti-VEGF) agents in the management of proliferative diabetic retinopathy and its complications.

METHODS

The authors identified randomized controlled trials using anti-VEGF agents, either as stand-alone therapy or combined with other interventions, in the management of proliferative diabetic retinopathy. The primary outcome measures were change in best-corrected visual acuity and (in the context of vitrectomy) duration of surgery and postoperative vitreous hemorrhage. Secondary outcomes were change in central retinal thickness and (in the context of vitrectomy) intraoperative variables suggestive of complex surgery (retinal breaks, intraoperative bleeding, and endodiathermy applications). The quality of evidence for all outcomes was appraised using the GRADE criteria.

RESULTS

Twenty-two studies involving 1,397 subjects met the criteria for inclusion in this study. One study compared intravitreal ranibizumab with saline, one compared intravitreal pegaptanib to pan-retinal photocoagulation (PRP), one compared intravitreal bevacizumab to PRP, 3 compared combined intravitreal ranibizumab/PRP to PRP, 5 compared combined intravitreal bevacizumab/PRP to PRP alone, and 11 compared combined intravitreal bevacizumab/PPV to PPV alone. When used in conjunction with PRP, there is a high-quality evidence to suggest that intravitreal ranibizumab is associated with superior visual acuity and central retinal thickness outcomes at 3 months to 4 months. In the context of PPV, there is moderate quality evidence to suggest that preoperative intravitreal bevacizumab results in a significant reduction in the duration of surgery, fewer retinal breaks, less intraoperative bleeding, and fewer endodiathermy applications. Although there is evidence to suggest occurrence of early postoperative vitreous hemorrhage is reduced, the quality of evidence in support of this finding is low.

CONCLUSION

The use of anti-VEGF agents before PRP results in superior functional and structural outcomes at 3 months to 4 months. The use of anti-VEGF agents before PPV results in decreased duration of surgery, fewer breaks, and less intra-operative bleeding. Although there is evidence for a decreased incidence of early postoperative vitreous hemorrhage, the quality of evidence is low. The available data therefore support the use of anti-VEGF agents as adjuncts to PRP and PPV in patients with complicated proliferative diabetic retinopathy primarily as a means of facilitating, and potentially minimizing the iatrogenic damage resulting from, these procedures.

Retinal region-dependent susceptibility of capillaries to high-concentration oxygen exposure and vascular endothelial growth factor receptor inhibition in neonatal mice

Retinal blood flow insufficiency due to capillary loss induces hypoxia in the retina, leading to an abnormal angiogenesis, relating to ischemic retinopathy. To better understand the mechanism and process of retinal capillary regression, we examined the process of hyperoxia- and vascular endothelial growth factor receptor (VEGFR) inhibitor-induced retinal capillary regression in neonatal mice. We also investigated the effects of Ca(2+) channel blockers, amlodipine and nicardipine, on hyperoxia-induced capillary regression. The regression of capillaries adjacent to arteries began immediately after the mice were exposed to 80% oxygen on postnatal day 7. An apparent avascular zone was established within 24 h after the initiation of oxygen exposure, whereas capillaries in the retinal vascular front were not affected. Axitinib, an inhibitor of VEGFR tyrosine kinase, induced capillary regression throughout the retinal vasculature. High-concentration oxygen exposure affected the capillaries on the arterial side of the retinal circulation more preferentially than axitinib. The Ca(2+) channel blockers significantly delayed hyperoxia-induced capillary regression and changes in the capillaries on the arterial side. These results suggest that the decreased blood flow due to arterial constriction contributes to hyperoxia-induced capillary regression. Compounds that improve the retinal blood flow may prevent ischemia by preventing capillary loss.

Anti-VEGF Therapy and the Retina: An Update

Ocular angiogenesis and macular oedema are major causes of sight loss across the world. Aberrant neovascularisation, which may arise secondary to numerous disease processes, can result in reduced vision as a result of oedema, haemorrhage, and scarring. The development of antivascular endothelial growth factor (anti-VEGF) agents has revolutionised the treatment of retinal vasogenic conditions. These drugs are now commonly employed for the treatment of a plethora of ocular pathologies including choroidal neovascularisation, diabetic macular oedema, and retinal vein occlusion to name a few. In this paper, we will explore the current use of anti-VEGF in a variety of retinal diseases and the impact that these medications have had on visual outcome for patients.

Anti-angiogenic effects of mammalian target of rapamycin inhibitors in a mouse model of oxygen-induced retinopathy

Ocular pathologic angiogenesis is a causative factor for retinopathy of prematurity, diabetic retinopathy, and age-related macular degeneration. In the present study, we examined the effects of rapamycin and everolimus, inhibitors of mammalian target of rapamycin (mTOR), on retinal pathologic angiogenesis in mice with oxygen-induced retinopathy (OIR), an animal model of proliferative ischemic retinopathy. Mice were exposed to 80% oxygen from postnatal day (P) 7 to P10, and were then brought into room air and subcutaneously injected with rapamycin and everolimus. The neovascular tufts, the size of the central avascular zone, and the immunoreactivity for phosphorylated ribosomal protein S6 (pS6), a downstream indicator of mTOR activity, were evaluated in flat-mounted retinas. Retinal neovascular tufts and vascular growth in the avascular zone were observed in P15 mice with OIR. In addition, intense immunoreactivity for pS6 was detected in the neovascular tufts and in endothelial cells located at the vascular-avascular border. Both rapamycin and everolimus reduced the extent of retinal neovascular tufts and pS6 immunoreactivity, but they also increased the size of the avascular zone. Thus, activation of the mTOR pathway in endothelial cells contributes to retinal pathologic angiogenesis, and mTOR inhibitors that target proliferating endothelial cells are promising candidates as anti-angiogenic agents for the treatment of vasoproliferative retinal diseases.

The role of CTGF in diabetic retinopathy

Connective tissue growth factor (CTGF, CCN2) contributes to fibrotic responses in diabetic retinopathy, both before clinical manifestations occur in the pre-clinical stage of diabetic retinopathy (PCDR) and in proliferative diabetic retinopathy (PDR), the late clinical stage of the disease. CTGF is a secreted protein that modulates the actions of many growth factors and extracellular matrix (ECM) proteins, leading to tissue reorganization, such as ECM formation and remodeling, basal lamina (BL) thickening, pericyte apoptosis, angiogenesis, wound healing and fibrosis. In PCDR, CTGF contributes to thickening of the retinal capillary BL and is involved in loss of pericytes. In this stage, CTGF expression is induced by advanced glycation end products, and by growth factors such as vascular endothelial growth factor (VEGF) and transforming growth factor (TGF)-β. In PDR, the switch from neovascularization to a fibrotic phase - the angio-fibrotic switch - in PDR is driven by CTGF, in a critical balance with vascular endothelial growth factor (VEGF). We discuss here the roles of CTGF in the pathogenesis of DR in relation to ECM remodeling and wound healing mechanisms, and explore whether CTGF may be a potential novel therapeutic target in the clinical management of early as well as late stages of DR.

Preoperative intravitreal bevacizumab and silicone oil tamponade for vitrectomy in diabetic retinopathy

AIM: To evaluate the outcomes and complications of vitrectomy for diabetic retinopathy using preoperative bevacizumab and silicone oil (SO) tamponade.

METHODS: Eighty-four eyes (64 patients) that underwent vitrectomy to treat severe proliferative diabetic retinopathy were enrolled in this retrospective, interventional, serial case study. All patients provided signed informed consent preoperatively and the off-label use of bevacizumab was discussed with the patients and confirmed in the signed consent forms. Bevacizumab injections and SO tamponades were used in all cases and intraoperative complications, postoperative complications and postoperative outcomes were analyzed. The primary outcome was the occurrence of intraoperative and postoperative bleeding during and after vitrectomy and SO removal. The secondary outcomes were other complications that occurred during the two surgeries, the surgical time and the postoperative best-corrected visual acuity (BCVA) in logMAR scale compared with the preoperative BCVA in logMAR. The statistical analysis was performed with GraphPad Prism 5 (GraphPad Software, La Jolla, CA) using a column analysis (column statistics and frequency distribution) for the noncomparative analysis and a paired t-test for the comparative study; P < 0.05 indicated statistical significance.

RESULTS: Eighty-four eyes of 64 patients were included in the study. Of the 88 eyes initially recruited, 4 eyes (0.45%) developed phthisis bulbi and were excluded from the statistical analysis. Bevacizumab was injected between 1 and 10 d before surgery, with a mean of 3.7 ± 2.2 d. Forty-six eyes (54.8%) had no complications during the surgery; 6 eyes (7.1%) had vitreous hemorrhage; 21 (25%) had a single retinal tear; 7 (8.3%) had two or more retinal tears, one of which was in the posterior pole, temporal to the fovea; 2 (2.4%) had retinal tears associated with hemorrhage; 1 (1.2%) had choroidal detachment; and 1 eye (1.2%) had dialysis in the temporal entrance of the trocar. After the surgery and SO removal, 60 eyes (71.4%) had no complications, 8 (9.5%) had vitreous hemorrhage, 2 (2.4%) had a macular hole, 2 (2.4%) had an epiretinal membrane, 7 (8.3%) had rhegmatogenous retinal detachment, 2 (2.4%) had neovascular glaucoma, 2 (2.4%) had a corneal trophic ulcer, and 1 (1.2%) had central venous occlusion. The surgical time ranged from 40 to 120 min, with a mean of 77.8 ± 20.7 min. The final status of the lens was 34 phakic eyes (40.5%) and 24 pseudophakic eyes (28.5%); in 26 eyes (31%), the lens was extracted via phacoemulsification combined with vitrectomy or SO removal. The preoperative BCVA in logMAR ranged from 0.1 to 3.0, with a mean of 1.6 ± 0.9; the postoperative BCVA in logMAR ranged from 0.0 to 3.0, with a mean of 0.9 ± 0.7; the preoperative and postoperative BCVA values were significantly different (P < 0.0001).

CONCLUSION: Bevacizumab may diminish intraoperative and postoperative bleeding, thus possibly facilitating intraoperative maneuvers, diminishing the complications and playing a role in the final outcomes of these eyes.

Combined Tractional and Rhegmatogenous Retinal Detachment in Proliferative Diabetic Retinopathy in the Anti-VEGF Era

Purpose. To investigate the clinical features, surgical outcomes, and prognostic factors of combined rhegmatogenous and tractional detachment (combined RD) in proliferative diabetic retinopathy (PDR) in recent years. Methods. Medical records of PDR and combined RD treated with vitrectomy from 2008 to 2013 were retrospectively reviewed. Results. A total of 57 eyes from 49 patients were included. Nine eyes had received panretinal photocoagulation (PRP) and 7 eyes had intravitreal bevacizumab (IVB) within 3 months before RD developed. Thirty-eight eyes (66.7%) had ≧3 sites of broad adhesion of fibrovascular proliferation (FVP). Thirty-three eyes (57.9%) showed active FVP. Thirty-four eyes (59.6%) had extent of RD involving 3 or 4 quadrants. The primary reattachment rate was 93.0%, and the final visual acuity (VA) improved by more than 3 lines in 80.7% of eyes. Neovascular glaucoma occurred in 4 eyes postoperatively. Poor preoperative VA, severe vitreoretinal adhesion, and broad extent of RD had significant correlation with poor visual outcomes. Conclusion. PRP or IVB might play a role in provoking combined RD. The anatomical and functional success rates of surgery were high. Poor preoperative VA and severe proliferations predicted poor visual outcomes.

A review of anti-VEGF agents for proliferative diabetic retinopathy

Previous research has implicated vascular endothelial growth factor (VEGF) in the pathogenesis of diabetic retinopathy (DR). Although many studies reviewed the use of anti-VEGF for diabetic macular oedema, little has been written about the use of anti-VEGF for proliferative diabetic retinopathy (PDR). This study is a review of relevant publications dealing with the use of anti-VEGF for the treatment of PDR. The articles were identified through systematic searches of PUBMED and the Cochrane Central Register of Controlled Trials. At the end of each section, we summarized the level of evidence of the scientific literature. Off-label use of anti-VEGF agents was found to be beneficial in PDR, especially in cases with neovascular glaucoma, persistent vitreous haemorrhage, and before vitrectomy. The disadvantages of the use of anti-VEGF are its short-effect duration, causing tractional retinal detachment in cases with pre-existing pre-retinal fibrosis and endophthalmitis in rare cases. There is no conclusive evidence from large randomized trials regarding the efficacy of anti-VEGF treatment in PDR. However, numerous case series, sound biochemical mechanism of action, and increasing experience with using anti-VEGF drugs can be used to support the ongoing use of this treatment modality in selected patients.

Intravitreal Avastin as an adjunct in patients with proliferative diabetic retinopathy undergoing pars plana vitrectomy

Objective: Intravitreal Bevacizumab (Avastin, Genentech Inc., San Francisco, CA) (IVB) has been shown to cause regression of neovessels in proliferative diabetic retinopathy due to its anti-angiogenic effects. This study was performed to investigate the role of Avastin as an adjunct to the management of patients with proliferative diabetic retinopathy undergoing pars plana vitrectomy.

Methodology: Fifty four eyes of 54 patients with proliferative diabetic retinopathy scheduled for surgery were included in the study. They were randomized to vitrectomy with preoperative IVB (group one) or standard vitrectomy (group 2). Group one underwent a single intravitreal injection of bevacizumab 1.25 mg /0.05ml one week prior to vitrectomy. Main outcome measures were best corrected visual acuity (BCVA) after surgery, post-operative complications.

Results: Mean age of the patients was 52.07±5.54 years (range 39-67). At 6 months, 20 patients in group one had BCVA better than baseline as compared to 12 patients in group 2. In group one, only one patient had early post-operative vitreous hemorrhage, whereas 11 patients in group two had early vitreous hemorrhage.

Conclusion: Preoperative IVB is helpful in improving BCVA post operatively, reducing the time of surgery, decreasing the incidence of intraoperative and postoperative bleeding and reducing the frequency of rubeosis and hyphaema.

Vitrectomy and panretinal photocoagulation reduces the occurrence of neovascular glaucoma in central retinal vein occlusion with vitreous hemorrhage

PURPOSE

The purpose of this study was to evaluate the best-corrected visual acuity and occurrence of neovascular glaucoma with vitrectomy (VT) and panretinal photocoagulation or without VT in central retinal vein occlusion (CRVO) associated with vitreous hemorrhage (VH).

METHODS

The charts from patients diagnosed as having CRVO with VH at Chang Gung Memorial Hospital (Taiwan) were reviewed. They were grouped based on whether they also underwent VT. The main outcome measurements were the best-corrected visual acuity and incidence of neovascular glaucoma.

RESULTS

There were 83 eyes that had CRVO with VH from 83 patients (VT group, 56 eyes; non-VT group, 27 eyes). There was no significant difference between the VT and non-VT groups in terms of age, gender, diabetes, hypertension, lens status, and follow-up period. The non-VT group had a better best-corrected visual acuity (P = 0.018) and less VH (P = 0.025) than the VT group at baseline; however, the VT group had a better best-corrected visual acuity at the end of the follow-up than the non-VT group (P < 0.001). Most importantly, there was a higher neovascular glaucoma development (37%) in the non-VT group compared with that (14.3%) in the VT group (P = 0.025).

CONCLUSION

The visual outcomes of CRVO with VH are unfavorable whether VT was performed. However, VT and panretinal photocoagulation improved visual acuity and reduced the incidence of neovascular glaucoma in CRVO with VH.