IVTA as adjunctive treatment to PRP and MPC for PDR and macular edema: a meta-analysis

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.

The Evolving Treatment of Diabetic Retinopathy

Purpose

To review the current therapeutic options for the management of diabetic retinopathy (DR) and diabetic macular edema (DME) and examine the evidence for integration of laser and pharmacotherapy.

Methods

A review of the PubMed database was performed using the search terms diabetic retinopathy, diabetic macular edema, neovascularization, laser photocoagulation, intravitreal injection, vascular endothelial growth factor (VEGF), vitrectomy, pars plana vitreous surgery, antiangiogenic therapy. With additional cross-referencing, this yielded 835 publications of which 301 were selected based on content and relevance.

Results

Many recent studies have evaluated the pharmacological, laser and surgical therapeutic strategies for the treatment and prevention of DR and DME. Several newer diagnostic systems such as optical coherence tomography (OCT), microperimetry, and multifocal electroretinography (mfERG) are also assisting in further refinements in the staging and classification of DR and DME. Pharmacological therapies for both DR and DME include both systemic and ocular agents. Systemic agents that promote intensive glycemic control, control of dyslipidemia and antagonists of the renin-angiotensin system demonstrate beneficial effects for both DR and DME. Ocular therapies include anti-VEGF agents, corticosteroids and nonsteroidal anti-inflammatory drugs. Laser therapy, both as panretinal and focal or grid applications continue to be employed in management of DR and DME. Refinements in laser devices have yielded more tissue-sparing (subthreshold) modes in which many of the benefits of conventional continuous wave (CW) lasers can be obtained without the adverse side effects. Recent attempts to lessen the burden of anti-VEGF injections by integrating laser therapy have met with mixed results. Increasingly, vitreoretinal surgical techniques are employed for less advanced stages of DR and DME. The development and use of smaller gauge instrumentation and advanced anesthesia agents have been associated with a trend toward earlier surgical intervention for diabetic retinopathy. Several novel drug delivery strategies are currently being examined with the goal of decreasing the therapeutic burden of monthly intravitreal injections. These fall into one of the five categories: non-biodegradable polymeric drug delivery systems, biodegradable polymeric drug delivery systems, nanoparticle-based drug delivery systems, ocular injection devices and with sustained release refillable devices. At present, there remains no one single strategy for the management of the particular stages of DR and DME as there are many options that have not been rigorously tested through large, randomized, controlled clinical trials.

Conclusion

Pharmacotherapy, both ocular and systemic, will be the primary mode of intervention in the management of DR and DME in many cases when cost and treatment burden are less constrained. Conventional laser therapy has become a secondary intervention in these instances, but remains a first-line option when cost and treatment burden are more constrained. Results with subthreshold laser appear promising but will require more rigorous study to establish its role as adjunctive therapy. Evidence to support an optimal integration of the various treatment options is lacking. Central to the widespread adoption of any therapeutic regimen for DR and DME is substantiation of safety, efficacy, and cost-effectiveness by a body of sound clinical trials.

Changes in Ocular Blood Flow after Ranibizumab Intravitreal Injection for Diabetic Macular Edema Measured Using Laser Speckle Flowgraphy

PURPOSE

To evaluate the effects of intravitreal ranibizumab (IVR) treatment on the blood flow of the optic nerve head (ONH) and of retinal vessels of the peripapillary region of eyes with diabetic macular edema (DME) assessed using laser speckle flowgraphy (LSFG).

METHODS

Forty eyes of 30 patients treated with IVR for DME were included in this prospective clinical study. Mean blur rate (MBR) and relative flow volume (RFV) of the ONH and of a superior retinal artery and an inferior retinal vein of the peripapillary region were measured using LSFG at baseline, 2 weeks (T1), and 1 month (T2) after IVR injection. In addition, best-corrected visual acuity (BCVA) and central retinal thickness (CRT) were measured in all cases.

RESULTS

The BCVA improved and CRT decreased significantly during the follow-up period (p < 0.010). MBR-related parameters of the ONH such as MBR of all area (MA), MBR of vascular area (MV), and MBR of tissue area (MT) decreased significantly at 2 weeks after IVR compared to baseline values (MA, p < 0.010). MBR-related parameters of the ONH such as MBR of all area (MA), MBR of vascular area (MV), and MBR of tissue area (MT) decreased significantly at 2 weeks after IVR compared to baseline values (MA, p < 0.010). MBR-related parameters of the ONH such as MBR of all area (MA), MBR of vascular area (MV), and MBR of tissue area (MT) decreased significantly at 2 weeks after IVR compared to baseline values (MA, p < 0.010). MBR-related parameters of the ONH such as MBR of all area (MA), MBR of vascular area (MV), and MBR of tissue area (MT) decreased significantly at 2 weeks after IVR compared to baseline values (MA, p < 0.010). MBR-related parameters of the ONH such as MBR of all area (MA), MBR of vascular area (MV), and MBR of tissue area (MT) decreased significantly at 2 weeks after IVR compared to baseline values (MA, p < 0.010). MBR-related parameters of the ONH such as MBR of all area (MA), MBR of vascular area (MV), and MBR of tissue area (MT) decreased significantly at 2 weeks after IVR compared to baseline values (MA, p < 0.010). MBR-related parameters of the ONH such as MBR of all area (MA), MBR of vascular area (MV), and MBR of tissue area (MT) decreased significantly at 2 weeks after IVR compared to baseline values (MA, p < 0.010). MBR-related parameters of the ONH such as MBR of all area (MA), MBR of vascular area (MV), and MBR of tissue area (MT) decreased significantly at 2 weeks after IVR compared to baseline values (MA, p < 0.010). MBR-related parameters of the ONH such as MBR of all area (MA), MBR of vascular area (MV), and MBR of tissue area (MT) decreased significantly at 2 weeks after IVR compared to baseline values (MA.

CONCLUSION

IVR injection leads to a reduction of ocular blood flow both in the ONH and in the retinal peripapillary vessels associated with peripapillary vessel constriction. The reduction of CRT and related improvement of vision may be related to the changes in ocular blood flow.

Vitreous and intraretinal macular changes in diabetic macular edema with and without tractional components

Diabetic macular edema (DME) is still one of the main causes of visual impairment. Repeated intravitreal injections of ranibizumab are considered the gold standard treatment, but the efficacy in patients with prominent cystic characteristics remains uncertain. In diabetic retinas, the identification of both antero-posterior and, particularly, tangential tractions is crucial to prevent misdiagnosis of tractional and refractory DME, and therefore to prevent poor treatment outcomes. The treatment of tractional DME with anti-VEGF injections could be poorly effective due to the influence of a tractional force. Pars plana vitrectomy (PPV) is a surgical procedure that has been widely used in the treatment of diffuse and refractory DME. Anatomical improvement, although stable and immediate, did not result in visual improvement. PPV with internal limiting membrane (ILM) peeling for the treatment of non-tractional DME in patients with prominent cysts (> 390 μm) causes subfoveal atrophy, defined as "floor effect". Epiretinal tangential forces and intraretinal change evaluation by SD-OCT of non-tractional DME are essential for determining appropriate management.

The effect of triamcinolone acetonide or bevacizumab on the levels of proinflammatory cytokines after retinal laser photocoagulation in pigmented rabbits

Although laser photocoagulation is a gold standard for the treatment of retinal ischemic diseases, thermal burn induces the inflammation and the progression of macular edema. To prevent this complication, combination therapy using anti-vascular endothelial growth factor (VEGF) drugs or steroids is clinically utilized, however the mechanisms are still unclear. In this study, we aimed to evaluate the changes in inflammatory and angiogenic cytokine levels in aqueous humor and vitreous body after intravitreal injection of bevacizumab (IVB) or triamcinolone (IVTA), as well as sub-Tenon injection of triamcinolone (STTA) after retinal laser photocoagulation in rabbits. Pigmented rabbits were treated with retinal laser photocoagulation and divided into 4 groups, namely Control (no additional treatment), IVB, IVTA or STTA accordingly. Samples of vitreous and aqueous humor were collected on post-treatment days 0, 1, 7 and 14. The levels of intraocular VEGF, interleukin-6 (IL-6), intercellular adhesion molecule-1 (ICAM-1) and monocyte chemotactic protein-1 (MCP-1) were measured using an immunoassay. The levels of VEGF, IL-6, ICAM-1 and MCP-1 were significantly elevated 1 day after laser treatment. IVTA and STTA significantly reduced the increase in the levels of VEGF, IL-6, ICAM-1 and MCP-1, while IVB reduced that of VEGF only in aqueous humor and vitreous body. The protein amount in the aqueous humor transiently increased 1 day after laser, and was significantly prevented by IVTA or STTA but not IVB. Data showed that bevacizumab only reduced intraocular VEGF after laser, while triamcinolone suppressed both the expression of VEGF and proinflammatory cytokines. We propose that these cytokine profiles may play an important role in the pathogenesis of inflammation after photocoagulation and the underlying mechanism of treatment with anti-VEGF drug and steroids.

Macular laser photocoagulation with or without intravitreal triamcinolone pretreatment for diabetic macular edema: a result from five randomized controlled trials

AIM

To assess possible benefits of intravitreal triamcinolone acetonide (IVTA) injection as pretreatment for macular laser photocoagulation (MLP) in patients with diabetic macular edema (DME).

METHODS

Published randomized controlled trials (RCTs) concerning MLP with or without IVTA pretreatment for DME were retrieved from databases CNKI, Medline, EMbase, Web of Science, and the Cochrane Library. A Meta-analysis on eligible studies was conducted using RevMan 5.0 software. Two investigators independently assessed the quality of the trials and extracted data. Main outcome measures included the change in best corrected visual acuity (BCVA), difference in central macular thickness (CMT) and adverse events reporting in particular elevated intraocular pressure within the follow-up period. The results were pooled using weight mean difference (WMD) or odds risk (OR) with their corresponding 95% confidence intervals (CI). A fixed- or random-effect model was employed depending on the heterogeneity of the inclusion trials.

RESULTS

Finally, five independent RCTs were identified and used for comparing MLP with IVTA pretreatment (131 eyes) with MLP alone (133 eyes, control group). The overall study quality was relatively higher according to the modified Jadad scale. The Meta-analysis showed that MLP with IVTA pretreatment significantly reduced CMT at one, three and six months (P=0.002, 0.0003 and 0.04, respectively), compared with MLP alone. The IVTA pretreatment group showed statistically significant improvements in BCVA at the one-month follow up as compared with the control group (P=0.03). At three- and six-month follow up, there was a beneficial trend towards improving visual acuity in the IVTA pretreatment group without statistical significance between groups (P=0.06 and 0.20, respectively). The incidence of elevation of intraocular pressure was significantly higher in the IVTA pretreatment group than in the control group (P<0.0001). No evidence of publication bias was present according to Begg's test and Egger's test. There was a low level of heterogeneity in the included studies.

CONCLUSION

This Meta-analysis indicates that MLP with IVTA pretreatment has a better therapeutic effect in terms of CMT reduction and earlier (1mo) visual improvement for patients with DME as compared with MLP alone. Further confirmation with rigorously well-designed multi-center trials is needed.

Intravitreal triamcinolone acetonide in the treatment of ophthalmic inflammatory diseases with macular edema: a meta-analysis study

PURPOSE

To perform a meta-analysis of randomized controlled trials (RCTs) that compared the effects of treatment with intravitreal injections of triamcinolone acetonide (TA) with the standard of care for ocular inflammatory diseases.

METHODS

Medline database was searched for causes of macular edema terms in association with intravitreal triamcinolone. The primary outcome of interest included changes in best corrected visual acuity (BCVA) and central macular thickness (CMT). Pooled summary estimates for primary outcomes were calculated as weighted mean differences (WMD) either on a fixed- or random-effect model.

RESULTS

A total of 8 studies were included for quantitative analysis. Treatment with intravitreal TA showed improvement in BCVA compared with standard of care at 1 month (WMD, -0.09; 95% confidence interval [CI], -0.17 to -0.02), at 4 months (WMD, -0.09; 95% CI, -0.15 to -0.03), at 6 months (WMD, -0.13; 95% CI, -0.21 to -0.05), and in CMT at 1 month (WMD, -88.14; 95% CI, -105.86 to -70.43). Increased intraocular pressure (IOP) among patients treated with intravitreal TA was found at 4 months (WMD, 2.83; 95% CI, 1.96 to 3.70), persisting also at 12 months (WMD, 3.78; 95% CI, 2.97 to 4.59), compared with those receiving the standard of care. All outcomes are mostly equivalent at further follow-up times.

CONCLUSIONS

Intravitreal injections of TA may offer certain advantages over the standard of care for ocular inflammatory diseases, especially in the early stage of follow-up. However, it is necessary to take into account risks and benefits of TA treatment for ocular inflammatory diseases due to possible ocular hypertension elicited, in general, by intravitreal injection of corticosteroids.

Advances in diabetic retinopathy

Diabetic retinopathy (DR) is a complication of long-term diabetes mellitus (DM). Over the last 2 decades lot of work has been on early diagnosis of DR and screening programs have been designed to help the masses. Large numbers of clinical studies have been done for patients of diabetes and DR wherein the role of blood sugar control, metabolic control, role of oral medicines for DR, role of imaging, fluorescein angiography, and retinal photocoagulation has been studied. Newer treatment modalities are being devised and studied for better patient care. We discuss these issues in our review highlight and newer advances over the last few years.

Intravitreal triamcinolone versus intravitreal bevacizumab for diabetic macular edema: a meta-analysis

AIM

To compare the efficacy of the sole intravitreal triamcinolone (IVT) versus intravitreal bevacizumab (IVB) alone or IVB combined with IVT in the treatment of diabetic macular edema (DME).

METHODS

Pertinent publications were identified through systematic searches of database and manually searching. Methodological quality of the literatures was valuated according to the Jadad Score. RevMan 5.1.0 was used to do the meta-analysis. Heterogeneity was determined and sensitivity was conducted.

RESULTS

Six studies were ultimately included in the meta-analysis. The results of our analysis showed IVT had a statistically significant improvement in vision over the IVB at 1 month and 3 months (P<0.01). However, the reduction was not significant regarding central macular thickness (CMT) during the earlier (1 month and 3 months) follow-up period (P=0.12, P=0.41, respectively). At later visit (6 months), IVT had a significant decrease in CMT when compared to IVB (P<0.01) while no significant improvement in visual acuity (VA) was observed (P=0.14). The incidence of intraocular hypertension was 13/102 in IVT group during follow-up period while 0/103 in IVB group. The difference was significant (P<0.01). With regards to IVT versus IVB combined with IVT, there were no significant differences in CMT at 1 month (P=0.86) and 3 months (P=0.06). The incidence of intraocular hypertension was 6/67 in IVT group during follow-up period while 4/66 in IVB+IVT group. But the difference was not significant (P=0.53).

CONCLUSION

Current evidence shows IVT is superior in improving VA at earlier follow-up (1 month and 3 months) and in reducing CMT at later follow-up (6 months) for DME. At other time, it is in favor of IVT treatment but there are no statistically significances. However, IVT has the side-effect of ocular hypertension. There is no adequate evidence of the benefit adding IVB to IVT in contrast to IVT alone.