Anti-VEGF Injections vs. Panretinal Photocoagulation Laser Therapy for Proliferative Diabetic Retinopathy: A Systematic Review and Meta-Analysis

TOPIC

To evaluate the efficacy and safety of anti-VEGF and panretinal photocoagulation (PRP) for the treatment of proliferative diabetic retinopathy (PDR). The outcomes examined are changes in best-corrected visual acuity (BCVA), neovascularization (NV), central macular thickness (CMT), and adverse outcomes.

CLINICAL RELEVANCE

Diabetic retinopathy is the leading cause of blindness in working-aged adults globally. At present, no consensus has been reached on the optimal choice for the treatment of PDR.

METHODS

Cochrane, Embase, PubMed, Scopus, Web of Science, and CiNAHL were searched for articles from their inception to June 2023 according to the Preferred Reporting Items for Systematic Reviews and Meta-analysis. The review was registered prospectively with PROSPERO (CRD42023437778). Tool data analysis was performed using RevMan software version 5.4 (Review Manager [RevMan] [computer program], The Cochrane Collaboration, 2020). Randomized control trials (RCTs) of PDR patients treated with anti-VEGF, PRP, or a combination were included. Risk of bias was assessed using the Rob2 assessment tool (revised tool for risk of bias in randomized trials), and certainty of evidence was assessed with the Grading Recommendations Assessment, Development and Evaluation (GRADE) approach.

RESULTS

Nineteen studies were included, with 1361 patients (n = 1788 eyes) treated for PDR with either anti-VEGF (n = 274), PRP (n = 482), or combination (n = 320). Our results show more favorable BCVA outcomes with anti-VEGF compared with PRP at 3 months (mean difference [MD] = 2.35 letters; 95% confidence interval [CI], 1.18-3.52; I2 = 0%) and 12 months follow-up (MD = 3.39 letters; 95% CI, 0.63-6.14; I2 = 26%). Combination treatment showed better BCVA outcomes compared with PRP at 12 months (MD = 4.06 letters; 95% CI, 0.26-7.86; I2 = 0%). Combination showed lower CMT at 3 months (MD = -33.10 μm; 95% CI, -40.12 to -26.08; I2 = 25%) and 6 months (MD = -34.28 μm; 95% CI, -55.59 to -12.97; I2 = 85%) compared with PRP, but CMT results were similar at 12 months. Complete regression of total NV (NVT) was more likely with anti-VEGF compared with PRP (odds ratio = 6.15; 95% CI, 1.39-27.15; I2 = 80%). Posttreatment vitreous hemorrhage, vitrectomy, and increased intraocular pressure events were similar between the anti-VEGF and combination groups compared with PRP; however, macular edema results favored the anti-VEGF over the PRP group. Using the GRADE assessment, BCVA evidence was rated to be of moderate certainty, whereas CMT and NVT evidence certainty was rated as very low.

CONCLUSION

Anti-VEGF and combination treatments could be regarded as alternative approaches to PRP alone in the management of PDR after engaging in a shared decision-making process based on patients' adherence, diabetic macular edema status, and preference. Limitations of this meta-analysis include the heterogeneity in participants' characteristics, treatment regimens, and outcome reporting between studies. Further RCTs should be conducted to compare the effectiveness of these treatments in the long term.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

A methodological quality review of citations of randomized controlled trials of diabetes type2 in leading clinical practice guidelines and systematic reviews

Objective

Evaluate methodological quality of type 2 diabetes RCTs conducted in Iran and cited in clinical practice guidelines and systematic reviews and meta-analyses.

Methods

We conducted a descriptive methodological quality review, analyzing 286 Randomized Controlled Trials (RCTs) on diabetes mellitus published in Iran from July 2004 to 2021. We searched six databases systematically and evaluated eligible articles using the CONSORT 2010 checklist for abstracts. Two investigators assessed the data using a 17-item checklist derived from CONSORT. Additionally, we examined the citations of each RCT in 260 clinical practice guidelines, with a specific focus on the adequate reporting of outcomes.

Results

Out of 6667 articles, 286 analyzed. Poor reporting and failure to meet criteria observed. Only 3.8% cited in guidelines. Reporting rates: primary outcomes (41.9%), randomization (61.8%), trial recruitment (12.6%), blinding (50.8%). 27.9% cited in systematic reviews, 50.34% in systematic reviews and meta-analyses, 26.57% in meta-analyses. 67.8% of papers cited in systematic reviews. Adherence highest for participants, objective, randomization, intervention, outcome; lowest for recruitment, trial design, funding source, harms, and reporting primary outcomes.

Conclusions

Poor methodological reporting and adherence to CONSORT checklist in evaluated RCTs, especially in methodological sections. Improvements needed for reliable and applicable results in guidelines, reviews, and meta-analyses. Inadequate outcome reporting challenges researchers, clinicians, and policymakers, impacting evidence-based decision-making. Urgent improvements in RCT registration necessary.

Regression of Neovascularization after Panretinal Photocoagulation Combined with Anti-VEGF Injection for Proliferative Diabetic Retinopathy-A Review

Proliferative diabetic retinopathy (PDR) poses a significant therapeutic problem that often results in severe visual loss. Panretinal photocoagulation (PRP) has long been a mainstay treatment for this condition. Conversely, intravitreal anti-VEGF therapy has served as an alternative treatment for PDR. This review aimed to evaluate the effects of PRP combined with anti-VEGF therapy on the regression of neovascularization (NV), including functional outcomes and incidence of complications. The MEDLINE database was searched for articles evaluating regression of NV using a combination of the following terms: "proliferative diabetic retinopathy", "anti-VEGF", "panretinal photocoagulation", and "combined treatment". The search yielded a total of 22 articles. The analysis of their results indicated PRP combined with ant-VEGF therapy as superior over PRP alone in the management of PDR. Combination treatment yields better and faster regression of NV and a lower incidence of serious complications, such as vitreous hemorrhage and the need for pars plana vitrectomy. Nevertheless, complete regression of NV is not achieved in a significant proportion of patients. Further research is needed to establish the most effective schedule for intravitreal injections as an adjunct to PRP. The current literature shows that in some cases, cessation of anti-VEGF injection in combination treatment for PDR can lead to relapse of NV.

The evolving therapeutic landscape of diabetic retinopathy

INTRODUCTION

Diabetic retinopathy (DR) is a leading cause of blindness worldwide. Recent decades have seen rapid progress in the management of diabetic eye disease, evolving from pituitary ablation to photocoagulation and intravitreal pharmacotherapy. The advent of effective intravitreal drugs inhibiting vascular endothelial growth factor (VEGF) marked a new era in DR therapy. Sustained innovation has since produced several promising biologics targeting angiogenesis, inflammation, oxidative stress, and neurodegeneration.

AREAS COVERED

This review surveys traditional, contemporary, and emerging therapeutics for DR, with an emphasis on anti-VEGF therapies, receptor tyrosine kinase inhibitors, angiopoietin-Tie2 pathway inhibitors, integrin pathway inhibitors, gene therapy 'biofactory' approaches, and novel systemic therapies. Some of these investigational therapies are being delivered intravitreally via sustained release technologies for extended durability. Other investigational agents are being delivered non-invasively via topical and systemic routes. These strategies hold promise for early and long-lasting treatment of DR.

EXPERT OPINION

The evolving therapeutic landscape of DR is rapidly expanding our toolkit for the effective and durable treatment of blinding eye disease. However, further research is required to validate the efficacy of novel therapeutics and characterize real world outcomes.

Anti-vascular endothelial growth factor for proliferative diabetic retinopathy

BACKGROUND

Proliferative diabetic retinopathy (PDR) is an advanced complication of diabetic retinopathy that can cause blindness. It consists of the presence of new vessels in the retina and vitreous haemorrhage. Although panretinal photocoagulation (PRP) is the treatment of choice for PDR, it has secondary effects that can affect vision. Anti-vascular endothelial growth factor (anti-VEGF), which produces an inhibition of vascular proliferation, could improve the vision of people with PDR.

OBJECTIVES

To assess the effectiveness and safety of anti-VEGFs for PDR and summarise any relevant economic evaluations of their use.

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Trials Register; 2022, Issue 6); Ovid MEDLINE; Ovid Embase; the ISRCTN registry; ClinicalTrials.gov, and the WHO ICTRP. We did not use any date or language restrictions. We last searched the electronic databases on 1 June 2022.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing anti-VEGFs to another active treatment, sham treatment, or no treatment for people with PDR. We also included studies that assessed the combination of anti-VEGFs with other treatments. We excluded studies that used anti-VEGFs in people undergoing vitrectomy.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies for inclusion, extracted data, and assessed the risk of bias (RoB) for all included trials. We calculated the risk ratio (RR) or the mean difference (MD), and 95% confidence intervals (CI). We used GRADE to assess the certainty of evidence.

MAIN RESULTS

We included 15 new studies in this update, bringing the total to 23 RCTs with 1755 participants (2334 eyes). Forty-five per cent of participants were women and 55% were men, with a mean age of 56 years (range 48 to 77 years). The mean glycosylated haemoglobin (Hb1Ac) was 8.45% for the PRP group and 8.25% for people receiving anti-VEGFs alone or in combination. Twelve studies included people with PDR, and participants in 11 studies had high-risk PDR (HRPDR). Twelve studies were of bevacizumab, seven of ranibizumab, one of conbercept, two of pegaptanib, and one of aflibercept. The mean number of participants per RCT was 76 (ranging from 15 to 305). Most studies had an unclear or high RoB, mainly in the blinding of interventions and outcome assessors. A few studies had selective reporting and attrition bias. No study reported loss or gain of 3 or more lines of visual acuity (VA) at 12 months. Anti-VEGFs ± PRP probably increase VA compared with PRP alone (mean difference (MD) -0.08 logMAR, 95% CI -0.12 to -0.04; I2 = 28%; 10 RCTS, 1172 eyes; moderate-certainty evidence). Anti-VEGFs ± PRP may increase regression of new vessels (MD -4.14 mm2, 95% CI -6.84 to -1.43; I2 = 75%; 4 RCTS, 189 eyes; low-certainty evidence) and probably increase a complete regression of new vessels (RR 1.63, 95% CI 1.19 to 2.24; I2 = 46%; 5 RCTS, 405 eyes; moderate-certainty evidence). Anti-VEGFs ± PRP probably reduce vitreous haemorrhage (RR 0.72, 95% CI 0.57 to 0.90; I2 = 0%; 6 RCTS, 1008 eyes; moderate-certainty evidence). Anti-VEGFs ± PRP may reduce the need for vitrectomy compared with eyes that received PRP alone (RR 0.67, 95% CI 0.49 to 0.93; I2 = 43%; 8 RCTs, 1248 eyes; low-certainty evidence). Anti-VEGFs ± PRP may result in little to no difference in the quality of life compared with PRP alone (MD 0.62, 95% CI -3.99 to 5.23; I2 = 0%; 2 RCTs, 382 participants; low-certainty evidence). We do not know if anti-VEGFs ± PRP compared with PRP alone had an impact on adverse events (very low-certainty evidence). We did not find differences in visual acuity in subgroup analyses comparing the type of anti-VEGFs, the severity of the disease (PDR versus HRPDR), time to follow-up (< 12 months versus 12 or more months), and treatment with anti-VEGFs + PRP versus anti-VEGFs alone. The main reasons for downgrading the certainty of evidence included a high RoB, imprecision, and inconsistency of effect estimates.

AUTHORS' CONCLUSIONS

Anti-VEGFs ± PRP compared with PRP alone probably increase visual acuity, but the degree of improvement is not clinically meaningful. Regarding secondary outcomes, anti-VEGFs ± PRP produce a regression of new vessels, reduce vitreous haemorrhage, and may reduce the need for vitrectomy compared with eyes that received PRP alone. We do not know if anti-VEGFs ± PRP have an impact on the incidence of adverse events and they may have little or no effect on patients' quality of life. Carefully designed and conducted clinical trials are required, assessing the optimal schedule of anti-VEGFs alone compared with PRP, and with a longer follow-up.

Diabetic Retinopathy – Diagnostics and Treatment Guidelines

Diabetic retinopathy is one of the most common complications of diabetes mellitus and represents a serious health, social and economic problem. With the expected increase in the number of patients with diabetes, it is becoming the leading cause of severe vision loss in the working-age population.  The presented guidelines summarize the current knowledge about this disease in order to standardize and update the procedures for the diagnosis, classification and treatment of diabetic retinopathy.

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.

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.

Amine oxidase copper-containing 3 (AOC3) inhibition: a potential novel target for the management of diabetic retinopathy

Background

Diabetic retinopathy (DR), a microvascular complication of diabetes, is the leading cause of visual impairment in people aged 20–65 years and can go undetected until vision is irreversibly lost. There is a need for treatments for non-proliferative diabetic retinopathy (NPDR) which, in comparison with current intravitreal (IVT) injections, offer an improved risk–benefit ratio and are suitable for the treatment of early stages of disease, during which there is no major visual impairment. Efficacious systemic therapy for NPDR, including oral treatment, would be an important and convenient therapeutic approach for patients and physicians and would reduce treatment burden. In this article, we review the rationale for the investigation of amine oxidase copper-containing 3 (AOC3), also known as semicarbazide-sensitive amine oxidase and vascular adhesion protein 1 (VAP1), as a novel target for the early treatment of moderate to severe NPDR. AOC3 is a membrane-bound adhesion protein that facilitates the binding of leukocytes to the retinal endothelium. Adherent leukocytes reduce blood flow and in turn rupture blood vessels, leading to ischemia and edema. AOC3 inhibition reduces leukocyte recruitment and is predicted to decrease the production of reactive oxygen species, thereby correcting the underlying hypoxia, ischemia, and edema seen in DR, as well as improving vascular function.

Conclusion

There is substantial unmet need for convenient, non-invasive treatments targeting moderately severe and severe NPDR to reduce progression and preserve vision. The existing pharmacotherapies (IVT corticosteroids and IVT anti-vascular endothelial growth factor-A) target inflammation and angiogenesis, respectively. Unlike these treatments, AOC3 inhibition is predicted to address the underlying hypoxia and ischemia seen in DR. AOC3 inhibitors represent a promising therapeutic strategy for treating patients with DR and could offer greater choice and reduce treatment burden, with the potential to improve patient compliance.

Intravitreal anti-vascular endothelial growth factor versus panretinal LASER photocoagulation for proliferative diabetic retinopathy: a systematic review and meta-analysis

OBJECTIVE

To systematically review and perform a meta-analysis on the available evidence for anti-vascular endothelial growth factor (anti-VEGF) monotherapy versus panretinal photocoagulation (PRP) for proliferative diabetic retinopathy (PDR).

DESIGN

Systematic review and meta-analysis PARTICIPANTS: Randomized clinical trials included participants ≥18 years old with clinical or angiographic evidence of PDR. Interventions included were anti-VEGF monotherapy and PRP. Excluded studies were those with potentially biased treatment allocation and those offering combination therapies.

METHODS

The primary outcome was mean change in best-corrected visual acuity. Secondary outcomes were the proportion of patients developing severe (<6/60) or moderate (6/24-6/60) vision loss, rates of vitrectomy or vitreous hemorrhage, worsening macula edema, and reduced visual field indices.

RESULTS

Five studies of varying quality met the inclusion criteria (n = 632). The anti-VEGF intervention arm had a mean difference of -0.08 logMAR or 4 Early Treatment Diabetic Retinopathy Study (EDTRS) letters gained (p = 0.02) when compared with PRP at 12 months. The difference in rates of vitrectomy and vitreous hemorrhage favoured anti-VEGF over PRP (risk difference [RD] -0.10, p = < 0.001 and RD -0.10, p = 0.003 respectively).

CONCLUSIONS

This meta-analysis of the available evidence in patients with early PDR demonstrates a potential benefit for anti-VEGF over PRP alone. However, these benefits must be weighed against the relative costs of treatment and the potential risks of loss to follow-up.

Aflibercept in Diabetic Retinopathy

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Effect of Aflibercept on Diabetic Retinopathy Severity and Visual Function in the RECOVERY Study for Proliferative Diabetic Retinopathy

PURPOSE

To evaluate the effect of intravitreal aflibercept on diabetic retinopathy (DR) severity and visual function in patients with proliferative DR (PDR) without diabetic macular edema (DME).

DESIGN

Prospective, longitudinal, multicenter clinical trial.

PARTICIPANTS

Forty eyes of 40 patients with PDR and no DME were enrolled in this study. Patients were randomized into monthly and quarterly 2-mg aflibercept injection cohorts and were treated over a period of 12 months.

METHODS

All patients underwent ultra-widefield fundus imaging including pseudocolor and fluorescein angiography using an Optos 200Tx device.

MAIN OUTCOME MEASURES

Severity of DR at baseline, month 6, and month 12 was evaluated using the DR severity scale (DRSS). The DRSS scores were correlated with the 25-item Visual Function Questionnaire (VFQ-25) and 39-item Visual Function Questionnaire (VFQ-39) scores at baseline and month 12.

RESULTS

Mean age of the patients was 48.2 years (range, 25-75 years), mean duration of diabetes mellitus was 16.1 years (range, 2-36 years), and median glycated hemoglobin level was 8.8% (IQR, 7.4%-10%). Both monthly and quarterly groups demonstrated a statistically significant regression in DRSS from baseline to month 12 (P < 0.001). The monthly group demonstrated a statistically significant greater regression of DRSS score at the month 6 visit compared with the quarterly group (P = 0.019). However, the difference between the two groups became statistically insignificant at month 12 visit (P = 0.309). Also no difference was found in mean VFQ-25 and VFQ-39 composite scores between the monthly and quarterly groups at month 12 (P = 0.947 and P = 0.921, respectively). The improvement in mean VFQ-25 and VFQ-39 composite scores at month 12 was correlated significantly with improvement in DRSS score (r = 0.384 and P = 0.039, and r = 0.361 and P = 0.046, respectively).

CONCLUSIONS

In this study of eyes with PDR without DME, both monthly and quarterly aflibercept injection groups showed significant improvement in DR severity at month 12 compared with baseline. The improvement in DRSS score was associated with an improvement in VFQ-25 and VFQ-39 composite score.

Anti-Vascular Endothelial Growth Factor Therapy as an Alternative or Adjunct to Pan-Retinal Photocoagulation in Treating Proliferative Diabetic Retinopathy: Meta-Analysis of Randomized Trials

Aim

To compare anti-vascular growth factor (anti-VEGF) pharmacotherapy with pan-retinal photocoagulation (PRP) for proliferative diabetic retinopathy (PDR).

Method

PubMed, Embase, Medline, the ClinicalTrials.gov and the Cochrane Central Register of Controlled Trials were reviewed systemically. Randomized controlled trials (RCT) on anti-VEGF therapy versus PRP or anti-VEGF agent combined with PRP versus PRP for PDR are eligible to be included. Outcome measures were regression and recurrence of neovascularization, change in best corrected vision acuity, development of vitreous hemorrhage, and need for vitrectomy. A meta-analysis was conducted using RevMan (Cochrane Collaboration, Oxford, United Kingdom).

Results

Twelve RCTs with a total of 1026 eyes were identified. The meta-analysis results showed that regression of neovascularization did not vary significantly among different treatment regimens (P=0.06), whereas the recurrence of new vessels was significantly lower in PRP monotherapy (P < 0.00001). The best corrected visual acuity was significantly improved with anti-VEGF monotherapy or in the combined group than in the PRP groups (P < 0.00001, P=0.04, respectively). Odds ratio for post-treatment vitreous hemorrhage and vitrectomy rate between anti-VEGF therapy and PRP were 0.65 (95% confidence interval, 0.45–0.95; P = 0.03), and 0.24 (95% confidence interval, 0.12–0.48; P < 0.0001).

Conclusion

Our meta-analysis indicates that anti-VEGF pharmacotherapy is associated with superior visual acuity outcomes and less PDR-related complications. However, there is insufficient evidence to suggest anti-VEGF therapy as an alternative to PRP.

Towards implementation of AI in New Zealand national diabetic screening program: Cloud-based, robust, and bespoke

Convolutional Neural Networks (CNNs) have become a prominent method of AI implementation in medical classification tasks. Grading Diabetic Retinopathy (DR) has been at the forefront of the development of AI for ophthalmology. However, major obstacles remain in the generalization of these CNNs onto real-world DR screening programs. We believe these difficulties are due to use of 1) small training datasets (<5,000 images), 2) private and 'curated' repositories, 3) locally implemented CNN implementation methods, while 4) relying on measured Area Under the Curve (AUC) as the sole measure of CNN performance. To address these issues, the public EyePACS Kaggle Diabetic Retinopathy dataset was uploaded onto Microsoft Azure™ cloud platform. Two CNNs were trained; 1 a "Quality Assurance", and 2. a "Classifier". The Diabetic Retinopathy classifier CNN (DRCNN) performance was then tested both on 'un-curated' as well as the 'curated' test set created by the "Quality Assessment" CNN model. Finally, the sensitivity of the DRCNNs was boosted using two post-training techniques. Our DRCNN proved to be robust, as its performance was similar on 'curated' and 'un-curated' test sets. The implementation of 'cascading thresholds' and 'max margin' techniques led to significant improvements in the DRCNN's sensitivity, while also enhancing the specificity of other grades.

Vascular endothelial growth factor inhibition and proliferative diabetic retinopathy, a changing treatment paradigm?

Prior to the development of panretinal photocoagulation (PRP) in the 1970s, proliferative diabetic retinopathy (PDR) was the most common cause of blindness in diabetic patients. The diabetic retinopathy study demonstrated that PRP could decrease severe visual loss from PDR by 50%. Since then and for the past four decades, PRP has been the treatment of choice for eyes with PDR. In the past decade, vascular endothelial growth factor (VEGF) inhibition has become the treatment of choice for diabetic macular edema (DME). When treated intensively with anti-VEGF drugs, about one-third of eyes with DME experience an improvement in their diabetic retinopathy severity scale. Randomized clinical trials comparing ranibizumab to PRP and aflibercept to PRP have shown that VEGF inhibitors cause regression of intraocular neovascularization but need to be given on a fairly regular basis. Despite these promising results, concerns about treatment adherence have surfaced. Patients with PDR that are treated solely with anti-VEGF drugs and somehow interrupt their treatment are at a high risk of developing irreversible blindness. Combination treatment of PRP plus an anti-VEGF drug may be the treatment of choice for PDR.

Revascularization after angiogenesis inhibition favors new sprouting over abandoned vessel reuse

Inhibiting pathologic angiogenesis can halt disease progression, but such inhibition may offer only a temporary benefit, followed by tissue revascularization after treatment stoppage. This revascularization, however, occurs by largely unknown phenotypic changes in pathologic vessels. To investigate the dynamics of vessel reconfiguration during revascularization, we developed a model of reversible murine corneal angiogenesis permitting longitudinal examination of the same vasculature. Following 30 days of angiogenesis inhibition, two types of vascular structure were evident: partially regressed persistent vessels that were degenerate and barely functional, and fully regressed, non-functional empty basement membrane sleeves (ebms). While persistent vessels maintained a limited flow and retained collagen IV+ basement membrane, CD31+ endothelial cells (EC), and α-SMA+ pericytes, ebms were acellular and expressed only collagen IV. Upon terminating angiogenesis inhibition, transmission electron microscopy and live imaging revealed that revascularization ensued by a rapid reversal of EC degeneracy in persistent vessels, facilitating their phenotypic normalization, vasodilation, increased flow, and subsequent new angiogenic sprouting. Conversely, ebms were irreversibly sealed from the circulation by excess collagen IV deposition that inhibited EC migration and prevented their reuse. Fully and partially regressed vessels therefore have opposing roles during revascularization, where fully regressed vessels inhibit new sprouting while partially regressed persistent vessels rapidly reactivate and serve as the source of continued pathologic angiogenesis.

The Different Facades of Retinal and Choroidal Endothelial Cells in Response to Hypoxia

Ocular angiogenic diseases, such as proliferative diabetic retinopathy and neovascular age-related macular degeneration, are associated with severe loss of vision. These pathologies originate from different vascular beds, retinal and choroidal microvasculatures, respectively. The activation of endothelial cells (EC) plays pivotal roles in angiogenesis, often triggered by oxygen deficiency. Hypoxia-inducible factors in ECs mediate the transcription of multiple angiogenic genes, including the canonical vascular endothelial growth factors. ECs show notable heterogeneity in function, structure, and disease, therefore the understanding of retinal/choroidal ECs (REC; CEC) biochemical and molecular responses to hypoxia may offer key insights into tissue-specific vascular targeting treatments. The aim of this review is to discuss the differences spanning between REC and CEC, with focus on their response to hypoxia, which could provide innovative and sustainable strategies for site specific targeting of ocular neovascularization.

The role of anti-vascular endothelial growth factor (anti-VEGF) in the management of proliferative diabetic retinopathy

Diabetes is a major cause of visual impairment among working-age adults in the United States. The proliferative form of diabetic retinopathy is associated with severe vision loss (acuity <5/200). The standard treatment in proliferative diabetic retinopathy (PDR) is panretinal photocoagulation (PRP), which is effective but has established side effects such as peripheral visual-field constraints. Vascular endothelial growth factor (VEGF) is thought to drive the process of vascular proliferation. Drugs targeting VEGF (anti-VEGF) have been studied extensively in diabetic macular edema (DME), and results have shown that diabetic retinopathy regresses with anti-VEGF treatment. Recent studies show that anti-VEGF is not inferior to PRP for PDR while treatment is maintained, though recurrence rate when anti-VEGF treatment is stopped is unclear. In vitreous hemorrhage where PRP cannot be performed, use of anti-VEGF medications can treat underlying PDR and delay or reduce need for vitrectomy. Limitations of anti-VEGF treatment, however, require careful patient selection and monitoring. This review discusses recent clinical trials and guidelines for anti-VEGF use in PDR.

Ranibizumab Plus Panretinal Photocoagulation versus Panretinal Photocoagulation Alone for High-Risk Proliferative Diabetic Retinopathy (PROTEUS Study)

PURPOSE

Comparison of the efficacy of ranibizumab (RBZ) 0.5 mg intravitreal injections plus panretinal photocoagulation (PRP) versus PRP alone in the regression of the neovascularization (NV) area in subjects with high-risk proliferative diabetic retinopathy (HR-PDR) over a 12-month period.

DESIGN

Prospective, randomized, multicenter, open-label, phase II/III study.

PARTICIPANTS

Eighty-seven participants (aged ≥18 years) with type 1/2 diabetes and HR-PDR (mean age, 55.2 years; 37% were female).

METHODS

Participants were randomized (1:1) to receive RBZ+PRP (n = 41) or PRP monotherapy (n = 46). The RBZ+PRP group received 3 monthly RBZ injections along with standard PRP. The PRP monotherapy group received standard PRP between day 1 and month 2; thereafter, re-treatments in both groups were at the investigators' discretion.

MAIN OUTCOME MEASURES

The primary outcome was regression of NV total, on the disc (NVD) plus elsewhere (NVE), defined as any decrease in the area of NV from the baseline to month 12. Secondary outcomes included best-corrected visual acuity (BCVA) changes from baseline to month 12, time to complete NV regression, recurrence of NV, macular retinal thickness changes from baseline to month 12, need for treatment for diabetic macular edema, need for vitrectomy because of occurrence of vitreous hemorrhage, tractional retinal detachment or other complications of DR, and adverse events (AEs) related to treatments.

RESULTS

Seventy-seven participants (88.5%) completed the study. Overall baseline demographics were similar for both groups, except for age. At month 12, 92.7% of participants in the RBZ+PRP group presented NV total reduction versus 70.5% of the PRP monotherapy participants (P = 0.009). The number of participants with NVD and NVE reductions was higher with RBZ+PRP (93.3% and 91.4%, respectively) versus PRP (68.8% and 73.7%, respectively), significant only for NVE (P = 0.048). Complete NV total regression was observed in 43.9% in the RBZ+PRP group versus 25.0% in the PRP monotherapy group (P = 0.066). At month 12, the mean BCVA was 75.2 letters (20/32) in the RBZ+PRP group versus 69.2 letters (20/40) in the PRP monotherapy group (P = 0.104). In the RBZ+PRP group, the mean number of PRP treatments over month 12 was 3.5±1.3, whereas in the PRP monotherapy group, it was 4.6±1.5 (P = 0.001). No deaths or unexpected AEs were reported.

CONCLUSIONS

Treatment with RBZ+PRP was more effective than PRP monotherapy for NV regression in HR-PDR participants over 12 months.

Current Advances in Pharmacotherapy and Technology for Diabetic Retinopathy: A Systematic Review

Diabetic retinopathy (DR) is classically defined by its vascular lesions and damage in the neurons of the retina. The cellular and clinical elements of DR have many features of chronic inflammation. Understanding the individual cell-specific inflammatory changes in the retina may lead to novel therapeutic approaches to prevent vision loss. The systematic use of available pharmacotherapy has been reported as a useful adjunct tool to laser photocoagulation, a gold standard therapy for DR. Direct injections or intravitreal anti-inflammatory and antiangiogenesis agents are widely used pharmacotherapy to effectively treat DR and diabetic macular edema (DME). However, their effectiveness is short term, and the delivery system is often associated with adverse effects, such as cataract and increased intraocular pressure. Further, systemic agents (particularly hypoglycemic, hypolipidemic, and antihypertensive agents) and plants-based drugs have also provided promising treatment in the progression of DR. Recently, advancements in pluripotent stem cells technology enable restoration of retinal functionalities after transplantation of these cells into animals with retinal degeneration. This review paper summarizes the developments in the current and potential pharmacotherapy and therapeutic technology of DR. Literature search was done on online databases, PubMed, Google Scholar, clinitrials.gov, and browsing through individual ophthalmology journals and leading pharmaceutical company websites.

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.

Vascular Complications of Diabetes

Over the last several decades, the global incidence and prevalence of diabetes mellitus has increased significantly. The raised incidence rate is projected to continue as greater numbers of persons adopt a Western lifestyle and diet. Patients with diabetes mellitus are at heightened risk of both adverse microvascular and cardiovascular events. Moreover, once cardiovascular disease develops, diabetes mellitus exacerbates progression and worsens outcomes. The medical management of patients with diabetes mellitus mandates comprehensive risk factor modification and antiplatelet therapy. Recent clinical trials of new medical therapies continue to inform the care of patients with diabetes mellitus to reduce both cardiovascular morbidity and mortality.

Vascular Endothelial Growth Factor Inhibitors for Diabetic Retinopathy

The prevalence of diabetes is growing at epidemic rates in the USA. Diabetic retinopathy develops in a large proportion of patients and is a leading cause of blindness worldwide. Systemic management of diabetic retinopathy has included glycemic, hypertension, and lipid control. Local ophthalmic treatment in the form of focal/grid or panretinal laser photocoagulation has been shown to prevent vision loss in diabetic edema and proliferative diabetic retinopathy, respectively. The introduction of anti-vascular endothelial growth factor for diabetic macular edema and retinopathy has provided clinicians with improved clinical outcomes with potentially less damaging effects than laser.

Anti-Vascular Endothelial Growth Factor Agents in the Treatment of Retinal Disease: From Bench to Bedside

The association of retinal hypoxia with retinal neovascularization has been recognized for decades, causing Michaelson to postulate in 1948 that a factor secreted by hypoxic retina was involved. The isolation of vascular endothelial growth factor (VEGF), characterization of its angiogenic activity, and demonstration that its expression was increased in hypoxic tissue made it a prime candidate. Intraocular levels of VEGF are elevated in patients with retinal or iris neovascularization, and VEGF-specific antagonists markedly suppress retinal neovascularization in mice and primates with ischemic retinopathy. Vascular endothelial growth factor antagonists also suppress choroidal neovascularization, and transgenic expression of VEGF in the retina of mice causes subretinal neovascularization. Clinical trials using a VEGF antagonist that blocks all isoforms of VEGF-A in patients with neovascular age-related macular degeneration (nAMD) demonstrated dramatic benefit. Similar results have been obtained with 2 other VEGF antagonists. Retinal hypoxia also contributes to diabetic macular edema (DME), and because of the absence of good animal models, small clinical trials were used to test the role of VEGF. The results clearly implicated VEGF as a major contributor to DME and have been confirmed by several large multicenter trials. A similar strategy demonstrated that VEGF is a major contributor to macular edema resulting from retinal vein occlusion, also confirmed in multicenter trials. Secondary outcomes in these large clinical trials have shown that VEGF inhibition improves retinal hemorrhages, retinal vessel closure, and progression of nonproliferative diabetic retinopathy. Anti-VEGF agents also provide therapeutic benefits in proliferative diabetic retinopathy. Thus, the development of VEGF antagonists has revolutionized the treatment of nAMD, diabetic retinopathy, and other ischemic retinopathies, but in many patients, the upregulation of VEGF is prolonged. Although the molecular signaling by which hypoxia and some other insults lead to upregulation of VEGF has been elucidated, it has not yet led to a treatment that reliably reduces the production of VEGF, necessitating continued neutralization by repeated intraocular injections of VEGF antagonists in many patients. The next horizon in the evolution of anti-VEGF therapy is the development of longer-acting agents or delivery platforms that provide sustained neutralization with fewer injections.

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.

Pan-retinal photocoagulation and other forms of laser treatment and drug therapies for non-proliferative diabetic retinopathy: systematic review and economic evaluation

BACKGROUND

Diabetic retinopathy is an important cause of visual loss. Laser photocoagulation preserves vision in diabetic retinopathy but is currently used at the stage of proliferative diabetic retinopathy (PDR).

OBJECTIVES

The primary aim was to assess the clinical effectiveness and cost-effectiveness of pan-retinal photocoagulation (PRP) given at the non-proliferative stage of diabetic retinopathy (NPDR) compared with waiting until the high-risk PDR (HR-PDR) stage was reached. There have been recent advances in laser photocoagulation techniques, and in the use of laser treatments combined with anti-vascular endothelial growth factor (VEGF) drugs or injected steroids. Our secondary questions were: (1) If PRP were to be used in NPDR, which form of laser treatment should be used? and (2) Is adjuvant therapy with intravitreal drugs clinically effective and cost-effective in PRP?

ELIGIBILITY CRITERIA

Randomised controlled trials (RCTs) for efficacy but other designs also used.

DATA SOURCES

MEDLINE and EMBASE to February 2014, Web of Science.

REVIEW METHODS

Systematic review and economic modelling.

RESULTS

The Early Treatment Diabetic Retinopathy Study (ETDRS), published in 1991, was the only trial designed to determine the best time to initiate PRP. It randomised one eye of 3711 patients with mild-to-severe NPDR or early PDR to early photocoagulation, and the other to deferral of PRP until HR-PDR developed. The risk of severe visual loss after 5 years for eyes assigned to PRP for NPDR or early PDR compared with deferral of PRP was reduced by 23% (relative risk 0.77, 99% confidence interval 0.56 to 1.06). However, the ETDRS did not provide results separately for NPDR and early PDR. In economic modelling, the base case found that early PRP could be more effective and less costly than deferred PRP. Sensitivity analyses gave similar results, with early PRP continuing to dominate or having low incremental cost-effectiveness ratio. However, there are substantial uncertainties. For our secondary aims we found 12 trials of lasers in DR, with 982 patients in total, ranging from 40 to 150. Most were in PDR but five included some patients with severe NPDR. Three compared multi-spot pattern lasers against argon laser. RCTs comparing laser applied in a lighter manner (less-intensive burns) with conventional methods (more intense burns) reported little difference in efficacy but fewer adverse effects. One RCT suggested that selective laser treatment targeting only ischaemic areas was effective. Observational studies showed that the most important adverse effect of PRP was macular oedema (MO), which can cause visual impairment, usually temporary. Ten trials of laser and anti-VEGF or steroid drug combinations were consistent in reporting a reduction in risk of PRP-induced MO.

LIMITATION

The current evidence is insufficient to recommend PRP for severe NPDR.

CONCLUSIONS

There is, as yet, no convincing evidence that modern laser systems are more effective than the argon laser used in ETDRS, but they appear to have fewer adverse effects. We recommend a trial of PRP for severe NPDR and early PDR compared with deferring PRP till the HR-PDR stage. The trial would use modern laser technologies, and investigate the value adjuvant prophylactic anti-VEGF or steroid drugs.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42013005408.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

New Therapeutic Approaches in Diabetic Retinopathy

Diabetic retinopathy is a common microvascular complication of diabetes mellitus. It affects a substantial proportion of US adults over age 40. The condition is a leading cause of visual loss. Much attention has been given to expanding the role of current treatments along with investigating various novel therapies and drug delivery methods. In the treatment of diabetic macular edema (DME), intravitreal pharmacotherapies, especially anti-vascular endothelial growth factor (anti-VEGF) agents, have gained popularity. Currently, anti-VEGF agents are often used as first-line agents in center-involved DME, with recent data suggesting that among these agents, aflibercept leads to better visual outcomes in patients with worse baseline visual acuities. While photocoagulation remains the standard treatment for proliferative diabetic retinopathy (PDR), recent FDA approvals of ranibizumab and aflibercept in the management of diabetic retinopathy associated with DME may suggest a potential for pharmacologic treatments of PDR as well. Novel therapies, including small interfering RNAs, chemokines, kallikrein-kinin inhibitors, and various anti-angiogenic agents, are currently being evaluated for the management of diabetic retinopathy and DME. In addition to these strategies, novel drug delivery methods such as sustained-release implants and refillable reservoir implants are either under active evaluation or have recently gained FDA approval. This review provides an update on the novel developments in the treatment of diabetic retinopathy.

Anti-vascular endothelial growth factor for proliferative diabetic retinopathy

BACKGROUND

Proliferative diabetic retinopathy (PDR) is a complication of diabetic retinopathy that can cause blindness. Although panretinal photocoagulation (PRP) is the treatment of choice for PDR, it has secondary effects that can affect vision. An alternative treatment such as anti-vascular endothelial growth factor (anti-VEGF), which produces an inhibition of vascular proliferation, could improve the vision of people with PDR.

OBJECTIVES

To assess the effectiveness and safety of anti-VEGFs for PDR.

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (2014, Issue 3), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to April 2014), EMBASE (January 1980 to April 2014), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 28 April 2014.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing anti-VEGFs to another active treatment, sham treatment or no treatment for people with PDR. We also included studies that assessed the combination of anti-VEGFs with other treatments.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies for inclusion, extracted data and assessed risk of bias for all included trials. We calculated the risk ratio (RR) or the mean difference (MD), and 95% confidence intervals (CI).

MAIN RESULTS

We included 18 RCTs with 1005 participants (1131 eyes) of whom 57% were men. The median number of participants per RCT was 40 (range 15 to 261). The studies took place in Asia (three studies), Europe (two studies), the Middle East (seven studies), North America (three studies) and South America (three studies). Eight RCTs recruited people eligible for PRP, nine RCTs enrolled people with diabetes requiring vitrectomy and one RCT recruited people undergoing cataract surgery. The median follow-up was six months (range one to 12 months). Seven studies were at high risk of bias and the remainder were unclear risk of bias in one or more domains.Very low quality evidence from one study of 61 people showed that people treated with bevacizumab and PRP were less likely to lose 3 or more lines of visual acuity at 12 months compared with people treated with PRP alone (RR 0.19, 95% CI 0.05 to 0.81). People treated with anti-VEGF had an increased chance of gaining 3 or more lines of visual acuity but the effect was imprecise and compatible with no effect or being less likely to gain vision (RR 6.78, 95% CI 0.37 to 125.95). No other study reported these two outcomes. On average, people treated with anti-VEGF (bevacizumab, pegaptanib or ranibizumab) had better visual acuity at 12 months compared with people not receiving anti-VEGF (MD -0.07 logMAR, 95% CI -0.12 to -0.02; 5 RCTs, 373 participants, low quality evidence). There was some evidence to suggest a regression of PDR with smaller leakage on fluorescein angiography but it was difficult to estimate a pooled result from the two trials reporting this outcome. People receiving anti-VEGF were less likely to have vitreous or pre-retinal haemorrhage at 12 months (RR 0.32, 95% CI 0.16 to 0.65; 3 RCTs, 342 participants, low quality evidence). No study reported on fluorescein leakage or quality of life.All of the nine trials of anti-VEGF before or during vitrectomy investigated bevacizumab; most studies investigated bevacizumab before vitrectomy, one study investigated bevacizumab during surgery.People treated with bevacizumab and vitrectomy were less likely to lose 3 or more lines of visual acuity at 12 months compared with people given vitrectomy alone but the effect was imprecise and compatible with no effect or being more likely to lose vision (RR 0.49, 95% CI 0.08 to 3.14; 3 RCTs, 94 participants, low quality evidence). People treated with bevacizumab were more likely to gain 3 or more lines of visual acuity (RR 1.62, 95% CI 1.20 to 2.17; 3 RCTs, 94 participants, low quality evidence). On average, people treated with bevacizumab had better visual acuity at 12 months compared with people not receiving bevacizumab but there was uncertainty in the estimate (the CIs included 0; i.e. were compatible with no effect, and there was considerable inconsistency between studies; MD -0.24 logMAR, 95% CI -0.50 to 0.01; 6 RCTs, 335 participants, I(2) = 67%; low quality evidence). People receiving bevacizumab were less likely to have vitreous or pre-retinal haemorrhage at 12 months (RR 0.30, 95% CI 0.18 to 0.52; 7 RCTs, 393 participants, low quality evidence). No study reported on quality of life.Reasons for downgrading the quality of the evidence included risk of bias in included studies, imprecision of the estimates, inconsistency of effect estimates and indirectness (few studies reported at 12 months).Adverse effects were rarely reported and there was no evidence for any increased risk with anti-VEGF but given the relatively few studies that reported these, and the low event rate, the power of the analysis to detect any differences was low.

AUTHORS' CONCLUSIONS

There was very low or low quality evidence from RCTs for the efficacy and safety of anti-VEGF agents when used to treat PDR over and above current standard treatments. However, the results suggest that anti-VEGFs can reduce the risk of intraocular bleeding in people with PDR. Further carefully designed clinical trials should be able to improve this evidence.

The 5-year onset and regression of diabetic retinopathy in Chinese type 2 diabetes patients

PURPOSE

To determine the rate and risk factors of diabetic retinopathy (DR) onset and regression in Chinese type 2 diabetes mellitus patients.

METHODS

This is a 5-year community-based prospective study. The demographic information, systemic examination results and ophthalmological test results of each participant were collected. The study outcomes were DR incidence, defined as the onset of DR in at least one eye, and DR regression, defined as full regression from existing DR to no retinopathy without invasive treatments. The associations between each potential risk factor and the outcomes were studied.

RESULTS

In total, 778 participants were enrolled. There were 322 patients without DR at baseline, of which 151 participants developed DR during follow-up (DR incidence rate = 46.89%). Baseline hyperglycemia and high blood pressure were two independent risk factors associated with DR incidence. Among the 456 participants with existing DR at entry, 110 fully recovered after 5 years (DR regression rate = 24.12%). Low baseline glucose and low serum triglyceride were two independent factors associated with DR regression.

CONCLUSIONS

DR incidence occurred more frequently in patients with hyperglycemia and high blood pressure. DR regression occurred mostly in patients with lower glucose and lower serum triglyceride levels among Chinese type 2 diabetes patients.

Identification of chemokines and growth factors in proliferative diabetic retinopathy vitreous

Associations were investigated between levels of chemokines and growth factors in the vitreous and proliferative diabetic retinopathy (PDR). Enrolled were 58 patients (58 eyes) requiring pars plana vitrectomy (PPV), with PDR (n=32, none with traction retinal detachment) or not (non-PDR). In the latter, 16 had macular hole (MH) and 10 had epiretinal membrane (ERM). With a multiplex bead immunoassay, levels of 11 chemokines and growth factors were measured from the undiluted vitreous sample from each patient. In the non-PDR eyes, the levels of the 11 chemokines and growth factors tested were similar between patients with MH and those with ERM. However, the levels of all 11 were significantly higher in the PDR eyes relative to the non-PDR; CCL17, CCL19, and TGFβ3 were markedly upregulated and have not been investigated in PDR previously. The significantly higher levels of CCL4 and CCL11 in PDR contradict the results of previous reports. Based on Spearman's nonparametric test, moderate-to-strong correlations were found between VEGF and other mediators. Our results indicate that these chemokines and growth factors could be candidates for research into targeted therapies applied either singly or in combination with anti-VEGF drugs for the treatment of PDR.

Systematic review of various laser intervention strategies for proliferative diabetic retinopathy

Diabetic retinopathy (DR) is a common complication of diabetes. DR obstructs blood supply to the retina and has serious and long-lasting detrimental effects on quality of life. Panretinal photocoagulation, a laser surgical intervention, is advocated for early treatment of DR to prevent visual loss; however, results from studies reporting its efficacy vary markedly. In this review, we systematically conducted a database search of randomized controlled trials that investigated the safety and efficacy of different types of laser interventions, alone or in combination with adjunct intravitreal steroid utilization, in patients with DR. Data from 14 studies demonstrated that panretinal photocoagulation can be a safe and effective option for reducing visual loss and blindness in patients with DR.

Recurrence of corneal neovascularization associated with lipid deposition after subconjunctival injection of bevacizumab

PURPOSE

To report 7 cases of recurrent corneal neovascularization (NV) and lipid deposition after subconjunctival injection of bevacizumab for the treatment of corneal NV-induced lipid keratopathy.

METHODS

We conducted a prospective interventional case series that included 20 eyes of chronic lipid keratopathy that received bevacizumab injection for the treatment of corneal NV and lipid deposition, including 7 eyes with recurrent corneal NV and lipid deposition after ceasing treatment. Repeated subconjunctival injections of bevacizumab were performed in 5 patients with recurrence. Penetrating keratoplasty was performed in 1 patient who had severely recurrent lipid deposition. Clinical presentation of corneal NV and lipid deposition, best-corrected visual acuity, and complications after treatments were recorded.

RESULTS

Bevacizumab inhibited corneal NV and lipid depositions in 19 patients. Seven of the 20 patients (35%) had different patterns of recurrence of corneal NV/lipid deposition 6 to 15 months after discontinuing treatment. Five of the 7 patients in whom corneal NV/lipid deposition was recurrent received another course of repeated bevacizumab treatments. Three eyes had partial response to the second course of treatment. Two eyes had too short re-treatment course to have conclusions. One patient who received penetrating keratoplasty had successful result after surgery.

CONCLUSIONS

Corneal NV and lipid deposition may recur after ceasing the subconjunctival bevacizumab injections for lipid keratopathy. Some patients respond at least partially to repeated injections.

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.

[VEGF inhibitors in vitreoretinal interventions]

Vascular endothelial growth factor (VEGF) inhibitors are being used for an increasing number of indications. Beyond the classical use in exudative macular degeneration and macular edema, they are being used, for example off-label as additive treatment together with panretinal laser photocoagulation or in preparation for vitrectomy for ischemic retinopathy. In preparation for vitreoretinal surgery VEGF inhibitors are usually given prior to surgery. When given as an adjunct to laser treatment, VEGF inhibitors can be given either consecutively or parallel to laser photocoagulation. In most cases, however, anti-VEGF treatment does not render laser coagulation dispensable. The greatest danger with anti-VEGF treatment in the context of ischemic retinopathies lies in the fact that proliferative membranes are misjudged or overlooked. In these cases, anti-VEGF treatment can induce contraction of these membranes with induction of consecutive tractional retinal detachment. This review summarizes the current knowledge on VEGF inhibition as an adjunct to vitreoretinal surgery and also points out the gaps in the current knowledge and the need for further research.

Intravitreal bevacizumab for proliferative diabetic retinopathy with new dense vitreous hemorrhage after full panretinal photocoagulation

PURPOSE

To evaluate the efficacy and safety of intravitreal bevacizumab (IVB) injections for the treatment of proliferative diabetic retinopathy (PDR) with new dense vitreous hemorrhage (VH) after previous full panretinal photocoagulation (PRP).

METHODS

Prospective study of consecutive PDR with prior complete PRP patients, who presented with new dense VH, were treated with IVB injection. Complete ophthalmic examination and/or ocular ultrasonography were performed at baseline and 1, 6, and 12 weeks and 6, 9, and 12 months after the first injection. Reinjection was done in non-clearing and recurrent VH.

RESULTS

Eighteen eyes of 18 patients, mean age 47.7 ± 12.69 years were included. In all, 14 (77.78%) patients had type 2 diabetes mellitus. Systemic hypertension and dyslipidemia were the most common systemic diseases. All cases were phakic eye with previous complete PRP. Patients received 1.6 ± 0.42 intravitreal injections over a 12-month period. VH cleared completely in 7 (38.89%), 9 (50%), and 13 (72.22%) eyes after 6 weeks, 6 months, and 12 months, respectively. Re-bleeding, however, occurred in 10 (56%) eyes during the follow-up period, and 5 (28%) eyes still had residual VH at the last visit. Statistically significant visual gain was observed in 9 (50%) eyes. Unfortunately, 2 (11%) eyes had severe visual loss because of the tractional retinal detachment (TRD). Mild ocular complication was detected in one patient.

CONCLUSION

IVB injection had good efficacy and safety for treatment of new VH in patients with PDR and prior complete PRP. This procedure may be especially relevant for diabetic patients at high-risk for surgical intervention.

Acute retinal pigment epithelium detachments after photocoagulation

PURPOSE

To characterize the morphology of patterned scanning laser (PASCAL) panretinal photocoagulation.

METHODS

In this prospective cohort study, patients with proliferative diabetic retinopathy or severe nonproliferative diabetic retinopathy with high-risk characteristics, who were treated with PASCAL panretinal photocoagulation as part of their indicated clinical course, were serially imaged with spectral domain optical coherence tomography. Thirty eyes of 25 patients were studied from 1 hour to 21 weeks after laser treatment.

RESULTS

Over a quarter (26.1%) of all treatment spots were imaged by spectral domain optical coherence tomography 1 hour after PASCAL panretinal photocoagulation. At 1 hour (±30 minutes) after PASCAL treatment, spectral domain optical coherence tomography demonstrated retinal pigment epithelium detachment in 23 of 27 eyes (85.2%) and in 36.1% of all imaged laser spots. Detachments occurred preferentially at the photocoagulation edges in 48.4% of pigment epithelium detachments (PEDs). Linear regression analysis revealed that average laser power (Pearson's r = 0.671, P < 0.001) and average laser energy (Pearson's r = 0.588, P = 0.001) were significantly associated with PEDs observed 1 hour after treatment. Pigment epithelium detachments occurred at a rate of 9.2% ± 4.9% at an average power of 0 mW to 400 mW, 37.8% ± 9.5% at 401 mW to 800 mW, 42.1% ± 5.6% at 801 mW to 1,200 mW, and 53.6% ± 5.7% at >1,200 mW. By a 1-week follow-up, no PEDs were observed, and the retinal pigment epithelium appeared morphologically similar to its preoperative structure by 3 weeks. Patient characteristics (study eye, sex, race, diagnosis, age, preoperative blood glucose, hemoglobin A1C, duration of diabetes, and body mass index) and other PASCAL parameters (number of laser applications, spot size, pulse duration, and average laser fluence) were not significantly associated with PEDs.

CONCLUSION

Retinal pigment epithelium detachment occurs 1 hour after PASCAL treatment over a wide range of laser settings. Laser power and energy are positively correlated with the occurrence of PEDs, which are no longer observed by 1-week follow-up. Future studies might examine various acute posttreatment time points and directly compare the morphology of PASCAL burns with that of longer pulse-duration laser modalities.

Antiangiogenic therapy for ischemic retinopathies

Neovascularization is a common pathological process in various retinal vascular disorders including diabetic retinopathy (DR), age-related macular degeneration (AMD) and retinal vein occlusion (RVO). The development of neovascular vessels may lead to complications such as vitreous hemorrhage, fibrovascular tissue formation, and traction retinal detachments. Ultimately, irreversible vision loss may result. Various proangiogenic factors are involved in these complex processes. Different antiangiogenic drugs have been formulated in an attempt treat these vascular disorders. One factor that plays a major role in the development of retinal neovascularization is vascular endothelial growth factor (VEGF). Anti-VEGF agents are currently FDA approved for the treatment of AMD and RVO. They are also extensively used as an off-label treatment for diabetic macular edema (DME), proliferative DR, and neovascular glaucoma. However, at this time, the long-term safety of chronic VEGF inhibition has not been extensively evaluated. A large and rapidly expanding body of research on angiogenesis is being conducted at multiple centers across the globe to determine the exact contributions and interactions among a variety of angiogenic factors in an effort to determine the therapeutic potential of antiangiogenic agent in the treatment of a variety of retinal diseases.

Regression activity that is naturally present in vitreous becomes ineffective as patients develop proliferative diabetic retinopathy

AIMS/HYPOTHESIS

The realisation that targeting agents in the vitreous is an effective approach to treating patients with diabetic retinopathy (DR) has increased awareness that changes in the composition/bioactivity of the vitreous is a contributor to the pathogenesis of DR. The overall goal of this study was to test the hypothesis that the vitreous has regression activity, and that lysophosphatidic acid (LPA) contributes to such activity. LPA is a bioactive phospholipid present in many biological fluids, and has been recently appreciated for its ability to promote regression of blood vessels.

METHODS

Vitreous-mediated regression was monitored on tubes organised from primary retinal endothelial cells or neovessels that sprouted from retinal explants. LPA was quantified radioenzymatically.

RESULTS

Bovine and human vitreous promoted regression of retinal explant vessels and of tubes organised from primary retinal endothelial cells. LPA was a substantial component of this regression activity. Comparing the regression activities of vitreous from patients with different stages of DR revealed that, as patients developed proliferative diabetic retinopathy (PDR), vitreous lost its ability to promote regression, even though the amount of LPA did not change. The underlying mechanism was a PDR-vitreous-mediated insensitivity to LPA, which could be overcome pharmacologically.

CONCLUSIONS/INTERPRETATION

Our findings suggest that a decline in the responsiveness to regression factors such as LPA, which are naturally present in the vitreous, contributes to the pathogenesis of PDR.

Contrast sensitivity evaluation in high risk proliferative diabetic retinopathy treated with panretinal photocoagulation associated or not with intravitreal bevacizumab injections: a randomised clinical trial

PURPOSE

To compare the effect on contrast sensitivity (CS) measurements of panretinal photocoagulation (PRP) associated with intravitreal bevacizumab (IVB) injections versus PRP alone in high risk proliferative diabetic retinopathy (HR-PDR).

DESIGN

Prospective, randomised, masked, controlled trial.

PARTICIPANTS

42 patients with HR-PDR with visual acuity ≥20/200.

METHODS

Eyes were randomised to one of two groups: one underwent PRP and IVB injections (study group) and the other PRP alone (control group). PRP was performed three times during the study and IVB injection was administered twice.

MAIN OUTCOME MEASURES

Mean change in CS threshold scores between and within groups, from baseline to 6 months.

RESULTS

Seven patients presented with vitreous haemorrhage and were removed from the study. Mean results for CS threshold (at 1.5, 3, 6, 12 and 18 cycles per degree (cpd) frequencies) for patients with and without diabetic macular oedema showed no significant differences (p>0.05 for all comparisons) between the two groups. In 35 eyes in the control group, compared with baseline values, there was significant worsening (p<0.05) of CS at 1.5, 12 and 18 cpd after 1 month, at 12 cpd after 3 months, and at 6 and 12 cpd after 6 months. In the study group, there was significant improvement in CS at 3 cpd, 3 months after treatment.

CONCLUSIONS

In eyes with HR-PDR, PRP treatment is associated with deterioration of CS while adjuvant use of bevacizumab prevents such deterioration. CS evaluation seems to support the adjuvant use of bevacizumab when using PRP for the treatment of HR-PDR. ClinicalTrials.gov Identifier NCT 01389505.

Pathophysiology and treatment of diabetic retinopathy

In the past years, the management of diabetic retinopathy (DR) relied primarily on a good systemic control of diabetes mellitus, and as soon as the severity of the vascular lesions required further treatment, laser photocoagulation or vitreoretinal surgery was done to the patient. Currently, even if the intensive metabolic control is still mandatory, a variety of different clinical strategies could be offered to the patient. The recent advances in understanding the complex pathophysiology of DR allowed the physician to identify many cell types involved in the pathogenesis of DR and thus to develop new treatment approaches. Vasoactive and proinflammatory molecules, such as vascular endothelial growth factor (VEGF), play a key role in this multifactorial disease. Current properly designed trials, evaluating agents targeting VEGF or other mediators, showed benefits in the management of DR, especially when metabolic control is lacking. Other agents, directing to the processes of vasopermeability and angiogenesis, are under investigations, giving more hope in the future management of this still sight-threatening disease.

Changes in the foveal microstructure after intravitreal bevacizumab application in patients with retinal vascular disease

PURPOSE

To investigate changes in the area of the foveal avascular zone (FAZ) in patients with retinal vascular disease.

PATIENTS AND METHODS

This retrospective, consecutive study examined 53 eyes of 53 patients with macular edema due to branch retinal vein occlusion in 25 patients (47.2%) and nonproliferative diabetic retinopathy in 28 patients (52.8%). The macular edema was treated with an intravitreal injection of 0.05 mL equal to 1.25 mg bevacizumab. Before and 6-8 weeks after the injection, best corrected visual acuity, slit lamp biomicroscopy of the anterior segment and fundus, optical coherence tomography, and fluorescein angiography were conducted. The FAZ was manually circumscribed on early-phase angiography images and the area of the FAZ was measured.

RESULTS

The preoperative overall mean FAZ area was 0.327 ± 0.126 mm(2) (median 0.310 mm(2)). At the control consultation, the overall mean area was significantly larger (0.422 ± 0.259 mm(2); median 0.380 mm(2); P < 0.001). In the nonproliferative diabetic retinopathy subpopulation, the mean area was 0.361 ± 0.129 mm(2) (median 0.330 mm(2)) before bevacizumab application and 0.434 mm(2) at the follow-up visit (mean increase 0.071 mm(2)/19.7%). In the branch retinal vein occlusion group, the baseline FAZ area was 0.290 ± 0.115 mm(2) and 0.407 ± 0.350 mm(2) at follow-up (median 0.330 mm(2); mean increase 0.117 mm(2)/40.3%). No cases of severe operation-associated complications were observed.

CONCLUSION

The results confirm the safety of intravitreal bevacizumab injection in patients with macular edema due to nonproliferative diabetic retinopathy and branch retinal vein occlusion. The enlargement of the FAZ could be equivalent to an increase in retinal ischemia. These results may be transient; a potential vascular risk, however, when applying antivascular endothelial growth factor therapy in eyes with preexistent vascular disease must be considered.