Diabetic macular edema: new concepts in patho-physiology and treatment

Effect of Baseline Subretinal Fluid on Treatment Outcomes in VIVID-DME and VISTA-DME Studies

PURPOSE

To evaluate the effect of baseline subretinal fluid (SRF) on treatment outcomes with intravitreal aflibercept injection (IAI) versus laser treatment in patients with diabetic macular edema (DME) in the VIVID and VISTA studies.

DESIGN

Post hoc analysis of 2 randomized controlled trials.

PARTICIPANTS

Eight hundred seventy-two patients with DME.

METHODS

We randomized patients to receive IAI 2 mg every 4 weeks (2q4), IAI 2 mg every 8 weeks after 5 monthly doses (2q8), or laser.

MAIN OUTCOME MEASURES

Effect of presence or absence of baseline SRF on visual outcomes in the integrated dataset at weeks 52 and 100.

RESULTS

Mean best-corrected visual acuity (BCVA) gains in the 2q4, 2q8, and laser arms at week 52 were +14.5, +11.0, and -2.3 letters, respectively, (those with baseline SRF) and +10.3, +10.6, and +2.5 letters, respectively, (those without). At week 100, mean gains were +13.5, +10.9, and -2.3 letters (those with baseline SRF) and +10.6, +10.0, and +2.7 letters (those without). The treatment effect for IAI versus laser from baseline to week 52 of 100 was greater for patients with baseline SRF versus those without (nominal P < 0.001, for interaction). The proportions of patients who gained 15 letters or more in the 2q4, 2q8, and laser arms at week 52 were 52.3%, 40.2%, and 8.9%, respectively, (those with baseline SRF) and 30.9%, 29.1%, and 8.2%, respectively, (those without) and at week 100 were 50.0%, 35.4%, and 12.9%, respectively, (those with baseline SRF) and 33.3%, 30.5%, and 12.5%, respectively, (those without). Time to first sustained SRF clearance seemed to be shorter in the IAI arms versus laser. The overall safety profile was similar in the IAI arms.

CONCLUSIONS

This post hoc analysis demonstrated the visual outcome benefits of IAI over laser, regardless of baseline SRF status. A greater treatment effect of IAI was observed in patients with baseline SRF versus those without; however, no meaningful impact of baseline SRF status on treatment outcomes with IAI was demonstrated, indicating that the differential effects of laser might have been the driving force behind the different treatment outcomes in both groups.

Efficacy of adjuvant topical timolol-dorzolamide with intravitreal bevacizumab injection in diabetic macular edema: A contralateral eye study

Purpose

To assess the efficacy of adjuvant topical timolol-dorzolamide with intravitreal bevacizumab (IVB) injection on anatomic and functional results in eyes affected with diabetic macular edema (DME).

Methods

In an interventional prospective contralateral pilot eye study at a third level referral academic facility, patients with bilateral DME who were treatment-naive were enrolled. Enrolled patients received a treatment plan of topical timolol-dorzolamide twice daily in the right eye. Three monthly bilateral IVB injections 1.25 mg/0.05 mL were also planned. Baseline central macular thickness (CMT) was measured by spectral-domain optical coherence tomography (SD-OCT), and clinical information such as best corrected visual acuity (BCVA) and intraocular pressure (IOP) were collected at enrollment and one month after the third injection.

Results

Eleven patients (seven females) with DME were included. BCVA and CMT improved in both eyes and IOP decreased in the right eye but did not change in the left eye. In repeated measures ANOVA analysis, the decrease in CMT and improvement in BCVA were significant in the right eye.

Conclusion

Our study suggested that adjuvant topical timolol-dorzolamide in combination with IVB may further reduce central macular thickness in eyes with DME.

Central subfield thickness and cube average thickness as bioimaging biomarkers for ellipsoid zone disruption in diabetic retinopathy

BACKGROUND

To evaluate the association of central subfield thickness (CST) and cube average thickness (CAT) with ellipsoid zone (EZ) disruption on spectral domain optical coherence tomography (SD-OCT) in patients of diabetic retinopathy (DR).

METHODS

Cross sectional study including consecutive patients of type 2 diabetes mellitus [without DR (No DR, n = 97); non-proliferative DR (NPDR, n = 91); proliferative DR (PDR, n = 83)] and healthy controls (n = 82) was undertaken. CST and CAT values were measured using SD-OCT. Data was analyzed using Chi square test, ANOVA and multivariate analysis. Discriminant values of CST and CAT for EZ disruption were evaluated using receiver operator characteristic curve. Area under curve (AUC) was computed.

RESULTS

Mean CAT and CST values in the study subjects showed an incremental trend. Multivariate ordinal logistic regression analysis showed increase in CST (OR = 1.022, p < 0.001) and CAT (OR = 1.029, p < 0.001) as significant independent predictors of EZ disruption. Area under curve showed excellent predictive results of CST (AUC = 0. 943 ± 0.021, 95% CI, 0.902-0.984, p < 0.05) and CAT (AUC = 0.959 ± 0.012, 95% CI 0.936-0.982, p < 0.05), as bioimaging biomarkers, for EZ disruption.

CONCLUSION

Increase in CST and CAT is associated with increased odds of EZ disruption and these macular parameters serve as bioimaging biomarkers for EZ disruption in DR.

Comparison of the effect of ranibizumab and dexamethasone implant on serous retinal detachment in diabetic macular edema

PURPOSE

To compare the efficacy of intravitreal ranibizumab (IVR) and intravitreal dexamethasone implant (IDI) on neurosensory retinal detachment (SRD) associated with diabetic macular edema (DME) in the early treatment period.

METHODS

This was a retrospective, interventional, case-control study. After three monthly loading doses of IVR or an initial IDI injection, the changes in best-corrected visual acuity (BCVA), central macular thickness (CMT) on OCT, and presence and height of SRD were evaluated.

RESULTS

The IVR and IDI groups consisted of 101 and 35 eyes, respectively. The mean changes in CMT in the IVR and IDI groups were 204.4±176.6 and 311.4±163, respectively (P<0.001). The mean changes in SRD height in the IVR and IDI groups were 133.6±92.1 and 168.6±103.9μm, respectively. The decrease in SRD height was significantly greater in the IDI group than in the IVR group (P=0.002). The SRD resolved completely in 72.2% and 71.4% of the patients in the IVR and IDI groups, respectively (P=0.9).

CONCLUSION

The mean reduction in CMT and SRD height was greater in the IDI group than in the IVR group. There was a negative correlation between baseline best-corrected visual acuity (BCVA) and SRD height and also between BCVA and CMT.

Review of clinical approaches in fluorescence lifetime imaging ophthalmoscopy

Autofluorescence-based imaging techniques have become very important in the ophthalmological field. Being noninvasive and very sensitive, they are broadly used in clinical routines. Conventional autofluorescence intensity imaging is largely influenced by the strong fluorescence of lipofuscin, a fluorophore that can be found at the level of the retinal pigment epithelium. However, different endogenous retinal fluorophores can be altered in various diseases. Fluorescence lifetime imaging ophthalmoscopy (FLIO) is an imaging modality to investigate the autofluorescence of the human fundus in vivo. It expands the level of information, as an addition to investigating the fluorescence intensity, and autofluorescence lifetimes are captured. The Heidelberg Engineering Spectralis-based fluorescence lifetime imaging ophthalmoscope is used to investigate a 30-deg retinal field centered at the fovea. It detects FAF decays in short [498 to 560 nm, short spectral channel (SSC) and long (560 to 720 nm, long spectral channel (LSC)] spectral channels, the mean fluorescence lifetimes (τm) are calculated using bi- or triexponential approaches. These are meant to be relatively independent of the fluorophore's intensity; therefore, fluorophores with less intense fluorescence can be detected. As an example, FLIO detects the fluorescence of macular pigment, retinal carotenoids that help protect the human fundus from light damages. Furthermore, FLIO is able to detect changes related to various retinal diseases, such as age-related macular degeneration, albinism, Alzheimer's disease, diabetic retinopathy, macular telangiectasia type 2, retinitis pigmentosa, and Stargardt disease. Some of these changes can already be found in healthy eyes and may indicate a risk to developing such diseases. Other changes in already affected eyes seem to indicate disease progression. This review article focuses on providing detailed information on the clinical findings of FLIO. This technique detects not only structural changes at very early stages but also metabolic and disease-related alterations. Therefore, it is a very promising tool that might soon be used for early diagnostics.

Intravitreal injection of a Rho-kinase inhibitor (fasudil) combined with bevacizumab versus bevacizumab monotherapy for diabetic macular oedema: a pilot randomised clinical trial

Background/aims

To compare the efficacy of combined intravitreal injection of bevacizumab and a Rho-kinase inhibitor, fasudil (intravitreal bevacizumab (IVB)/intravitreal fasudil (IVF)), with IVB alone for centre-involving diabetic macular oedema (DME).

Methods

In this prospective randomised clinical trial, 44 eyes with centre-involving DME were randomised into two groups. The combined group received three consecutive injections of IVB (1.25 mg) and IVF (50 µM/L) monthly, while the monotherapy group received only one IVB (1.25 mg) injection per month for 3 months. Changes in best-corrected visual acuity (BCVA) and central macular thickness (CMT) were compared between the two groups at months 3 and 6. The primary outcome measure was the mean change in BCVA at month 6.

Results

Mean BCVA was significantly improved in both groups at month 3 (P<0.001), but it persisted up to month 6 only in the IVB/IVF group. Improvement of BCVA was greater in the IVB/IVF group at both time points (P=0.008, P<0.001). In the IVB/IVF and IVB groups, 54.5% versus 10% of the eyes gained≥15 ETDRS letters at month 6 (P=0.026). Between months 3 and 6, mean BCVA significantly decreased by 5±7 ETDRS letters in the IVB group (P=0.002), while no significant deterioration was observed in the IVB/IVF group. Corresponding with the BCVA changes, CMT was significantly reduced in both groups at month 3 (p=0.006, p<0.001) but this reduction sustained only in the IVB/IVF group up to month 6 (p<0.001).

Conclusion

Adjunctive intravitreal injection of a Rho-kinase inhibitor may enhance and prolong the therapeutic effects of anti-vascular endothelial growth factor drugs for centre- involving DME.

Macular integrity assessment to determine the association between macular microstructure and functional parameters in diabetic macular edema

AIM

To respectively evaluate macular morphological features and functional parameters by using spectral-domain optical coherence tomography (SD-OCT) and macular integrity assessment (MAIA) in patients with diabetic macular edema (DME).

METHODS

This prospective, non-controlled, open study included 61 eyes of 38 consecutive patients with DME. All patients underwent best-corrected visual acuity (BCVA) measurement, MAIA microperimetry, and SD-OCT. DME morphology, including central retinal thickness (CRT) and central retinal volume (CRV); integrity of the external limiting membrane (ELM) and photoreceptor inner segment/outer segment (IS/OS) junction; and the deposition of hard macular exudates were assessed within a 1000-µm central subfield area. MAIA microperimetry parameters evaluated were average threshold (AT)-retinal sensitivity, macular integrity index (MI), fixation points within a circle of radius 1° (P1) and 2° (P2), and bivariate contour ellipse area considering 63% and 95% of the fixation points (A63 and A95, respectively).

RESULTS

MI was significantly higher in eyes with disrupted ELM or IS/OS, compared with eyes with intact ELM and IS/OS. Values of BCVA (logMAR), total AT, AT within 1000-µm diameter, P2, A63, A95, and CRT were significantly worse in eyes with disrupted IS/OS, compared with eyes with intact IS/OS. The values of BCVA (logMAR), AT within 1000-µm diameter, and CRT were significantly worse in eyes with disrupted ELM, compared with eyes with intact ELM. These parameters were not significantly different between eyes with or without hard macular exudate deposition. CRV was not significantly different in the presence or absence of the integrity of ELM, IS/OS, or deposition of hard macular exudates. At the center, nasal and temporal sectors of the fovea, significant negative correlations were observed between retinal thickness and AT of the corresponding area. At the inferior and superior sectors of the fovea, no correlations were observed between retinal thickness and AT of the corresponding area. In the intact IS/OS group, significant negative correlations were observed between CRT and central AT. There was no correlation between retinal sensitivity and thickness when the IS/OS layer was disrupted. Multiple linear regression analyses revealed that IS/OS integrity was an independent factor affecting MI.

CONCLUSION

Functional (BCVA and visual field) and morphological parameters (retinal thickness) were significantly associated with an intact IS/OS. Local photoreceptor integrity was a strong predictor of local visual function throughout the retina. MI revealed the functional status in DME, reflecting the IS/OS juction status in the macula.

EFFECTS OF INTRAVITREAL RANIBIZUMAB AND BEVACIZUMAB ON THE RETINAL VESSEL SIZE IN DIABETIC MACULAR EDEMA

PURPOSE

The goal of this study was to assess the effects of a single injection of intravitreal ranibizumab (RAN) or bevacizumab (BEV) on the retinal vessel size in eyes with diabetic macular edema.

MATERIALS AND METHODS

In total, 32 patients were enrolled in the RAN group, and 30 patients were included in BEV group. Each of these groups was also subdivided into two others groups: a study group and a control group. The study groups were composed of the injected eyes, whereas the noninjected fellow eyes served as the control groups. The patients underwent complete ophthalmic examinations, including optical coherence tomography and fundus fluorescein angiography, and the primary outcome measures included the central retinal artery equivalent, central retinal vein equivalent, and artery-to-vein ratio.

RESULTS

In the RAN study group (n = 32), the preinjection mean central retinal artery equivalent (175.42 μm) decreased to 169.01 μm after 1 week, and to 167.47 μm after 1 month (P < 0.001), whereas the baseline central retinal vein equivalent (235.29 μm) decreased initially to 219.90 μm after 1 week, and to 218.36 μm after 1 month (P < 0.001). In the BEV study group (n = 30), the preinjection central retinal artery equivalent (150.21 μm) decreased to 146.25 μm after 1 week, and to 145.89 μm after 1 month (P < 0.001); whereas the baseline central retinal vein equivalent (211.87 μm) decreased initially to 204.59 μm after 1 week and was 205.24 μm after 1 month (P < 0.001). The preinjection artery-to-vein ratio values changed significantly (P = 0.001) after 1 week and after 1 month in the RAN group, but no significant alteration in the artery-to-vein ratio was observed in the BEV group (P = 0.433). In both the RAN (n = 32) and BEV (n = 30) control groups, none of the 3 parameters changed throughout the study period, when compared with the baseline.

CONCLUSION

The results of this study showed that both RAN and BEV injections significantly constricted the retinal blood vessel diameters.

Vision Outcomes Following Anti-Vascular Endothelial Growth Factor Treatment of Diabetic Macular Edema in Clinical Practice

PURPOSE

To determine monitoring and treatment patterns and vision outcomes in real-world patients initiating anti-vascular endothelial growth factor (anti-VEGF) therapy for diabetic macular edema (DME).

DESIGN

Retrospective interventional cohort study.

METHODS

Setting: Electronic medical record analysis of Geisinger Health System data.

STUDY POPULATION

A total of 110 patients (121 study eyes) initiating intravitreal ranibizumab or bevacizumab for DME during January 2007‒May 2012, with baseline corrected visual acuity of 20/40 to 20/320, and ≥1 ophthalmologist visit during follow-up.

MAIN OUTCOME MEASURES

Intravitreal injections per study eye during the first 12 months; corrected visual acuity, change in corrected visual acuity from baseline, proportions of eyes with ≥10 or ≥15 approximate Early Treatment Diabetic Retinopathy Study letter gain/loss at 12 months; number of ophthalmologist visits.

RESULTS

Over 12 months, mean number of ophthalmologist visits was 9.2; mean number of intravitreal injections was 3.1 (range, 1-12), with most eyes (68.6%) receiving ≤3 injections. At 12 months, mean corrected visual acuity change was +4.7 letters (mean 56.9 letters at baseline); proportions of eyes gaining ≥10 or ≥15 letters were 31.4% and 24.0%, respectively; proportions of eyes losing ≥10 or ≥15 letters were 10.8% and 8.3%, respectively. Eyes receiving adjunctive laser during the first 6 months (n = 33) showed similar change in corrected visual acuity to non-laser-treated eyes (n = 88) (+3.1 vs +5.3 letters at 12 months).

CONCLUSIONS

DME patients receiving anti-VEGF therapy in clinical practice undergo less frequent monitoring and intravitreal injections, and achieve inferior vision outcomes to patients in landmark clinical trials.

ILUVIEN® technology in the treatment of center-involving diabetic macular edema: a review of the literature

Diabetic macular edema (DME) is one of the major causes of blindness, caused primarily by hyperglycemia and results from multiple pathological processes mostly secondary to increased levels of VEGF and other inflammatory cytokines. DME management includes control of systemic risk factors together with laser photocoagulation, frequent intraocular injections of anti-VEGF agents and steroids implants. Recent adoption of novel alternative drug delivery options has led to the development of sustained release ocular implants with longer duration of action with less injection frequency. This article will review the pharmacology and clinical data in terms of efficacy, safety and benefits of the sustained release steroid implants in treatment of DME with special emphasis on the fluocinolone acetonide ILUVIEN^® implant.

MALAT1: An Epigenetic Regulator of Inflammation in Diabetic Retinopathy

Despite possessing limited protein-coding potential, long non-coding RNAs (lncRNAs) have been implicated in a myriad of pathologic conditions. Most well documented in cancer, one prominent intergenic lncRNA known as MALAT1 is notorious for its role in impacting epigenetic mechanisms. In this study, we established a novel epigenetic paradigm for MALAT in diabetic retinopathy (DR) by employing siRNA-mediated MALAT1 knockdown in human retinal endothelial cells (HRECs), a Malat1 knockout animal model, vitreous humor from diabetic patients, pharmacological inhibitors for histone and DNA methylation, RNA immunoprecipitation, western blotting, and a unique DNA methylation array to determine glucose-related alterations in MALAT1. Our findings indicated that MALAT1 is capable of impacting the expressions of inflammatory transcripts through its association with components of the PRC2 complex in diabetes. Furthermore, the vitreous humors from diabetic patients revealed increased expressions of MALAT1, TNF-α, and IL-6. Intriguingly, our DNA methylation array demonstrated that transient high glucose exposure in HRECs does not contribute to significant methylation alterations at CpG sites across the MALAT1 gene. However, global inhibition of DNA methyltransferases induced significant increases in MALAT1 and associated inflammatory transcripts in HRECs. Our findings collectively demonstrate the importance of MALAT1 in inflammation and epigenetic regulation in DR.

Cystoid edema, neovascularization and inflammatory processes in the murine Norrin-deficient retina

Mutations in the Norrin (NDP) gene cause severe developmental blood vessel defects in the retina leading to congenital blindness. In the retina of Ndph-knockout mice only the superficial capillary network develops. Here, a detailed characterization of this mouse model at late stages of the disease using in vivo retinal imaging revealed cystoid structures that closely resemble the ovoid cysts in the inner nuclear layer of the human retina with cystoid macular edema (CME). In human CME an involvement of Müller glia cells is hypothesized. In Ndph-knockout retinae we could demonstrate that activated Müller cells were located around and within these cystoid spaces. In addition, we observed extensive activation of retinal microglia and development of neovascularization. Furthermore, ex vivo analyses detected extravasation of monocytic cells suggesting a breakdown of the blood retina barrier. Thus, we could demonstrate that also in the developmental retinal vascular pathology present in the Ndph-knockout mouse inflammatory processes are active and may contribute to further retinal degeneration. This observation delivers a new perspective for curative treatments of retinal vasculopathies. Modulation of inflammatory responses might reduce the symptoms and improve visual acuity in these diseases.

Clinical Decision-Making when Treating Diabetic Macular Edema Patients with Dexamethasone Intravitreal Implants

Diabetes mellitus (DM) is a metabolic disease frequently associated with comorbidities that include diabetic macular edema (DME). The current medical approach to treating DME involves intravitreal injections with either anti-vascular endothelial growth factors or steroids. However, the burden associated with intravitreal injections and DM-derived complications is high, underlining the need to find optimal treatment regimens. In this article we describe the considerations we apply when treating DME patients with dexamethasone intravitreal implants (Ozurdex®), particularly those that influence the clinical decision-making process during the follow-up period. These considerations are based both on the available medical literature and on our clinical experience following the use of these implants in this type of patient, the goal being to optimize the number of injections and the clinical outcome of this therapy. We also provide a general overview of the pathophysiology of DME, highlighting the inflammatory component as a rationale to use steroids in these patients.

Diabetic macular oedema: under-represented in the genetic analysis of diabetic retinopathy

Diabetic retinopathy, a complication of both type 1 and type 2 diabetes, is a complex disease and is one of the leading causes of blindness in adults worldwide. It can be divided into distinct subclasses, one of which is diabetic macular oedema. Diabetic macular oedema can occur at any time in diabetic retinopathy and is the most common cause of vision loss in patients with type 2 diabetes. The purpose of this review is to summarize the large number of genetic association studies that have been performed in cohorts of patients with type 2 diabetes and published in English-language journals up to February 2017. Many of these studies have produced positive associations with gene polymorphisms and diabetic retinopathy. However, this review highlights that within this large body of work, studies specifically addressing a genetic association with diabetic macular oedema, although present, are vastly under-represented. We also highlight that many of the studies have small patient numbers and that meta-analyses often inappropriately combine patient data sets. We conclude that there will continue to be conflicting results and no meaningful findings will be achieved if the historical approach of combining all diabetic retinopathy disease states within patient cohorts continues in future studies. This review also identifies several genes that would be interesting to analyse in large, well-defined cohorts of patients with diabetic macular oedema in future candidate gene association studies.

Role of Inflammation in Diabetic Retinopathy

Diabetic retinopathy is a common complication of diabetes and remains the leading cause of blindness among the working-age population. For decades, diabetic retinopathy was considered only a microvascular complication, but the retinal microvasculature is intimately associated with and governed by neurons and glia, which are affected even prior to clinically detectable vascular lesions. While progress has been made to improve the vascular alterations, there is still no treatment to counteract the early neuro-glial perturbations in diabetic retinopathy. Diabetes is a complex metabolic disorder, characterized by chronic hyperglycemia along with dyslipidemia, hypoinsulinemia and hypertension. Increasing evidence points to inflammation as one key player in diabetes-associated retinal perturbations, however, the exact underlying molecular mechanisms are not yet fully understood. Interlinked molecular pathways, such as oxidative stress, formation of advanced glycation end-products and increased expression of vascular endothelial growth factor have received a lot of attention as they all contribute to the inflammatory response. In the current review, we focus on the involvement of inflammation in the pathophysiology of diabetic retinopathy with special emphasis on the functional relationships between glial cells and neurons. Finally, we summarize recent advances using novel targets to inhibit inflammation in diabetic retinopathy.

A novel and less invasive technique to assess cytokine profile of vitreous in patients of diabetic macular oedema

PurposeA pilot study to validate the collection of vitreous reflux (VR) after intravitreal injection using Schirmers tear strips was carried out. We assessed its efficiency for proteomics studies by estimating the differential expression of 27 cytokines using multiplexed bead array in diabetic macular oedema and proliferative diabetic retinopathy. To set, validate and assess the efficacy of Schirmer tear strips for collecting VR in patients undergoing intravitreal injections for diabetic macular oedema (DME).Patients and methodsVR samples were collected from 11 eyes of DME patients after intravitreal injections using Schirmer tear strips. Undiluted vitrectomy samples were obtained from six eyes of non-diabetic patients with idiopathic macular hole and seven eyes of diabetic patients with high-risk proliferative diabetic retinopathy (Hr-PDR), which were also subsampled on the Schirmer tear strips. Tear sampling was done in a subset of the DME patients. Total protein concentration between VR and vitrectomy samples was compared. Levels of the set of 27 cytokines in Schirmer tear strips samples were measured. Inter-group comparison for cytokines was done using Mann-Whitney U-test.ResultsSimilar protein concentration in VR samples and vitrectomy samples (P<0.05) was obtained. Tear protein contamination was not detected in VR samples. In comparison with no-DR patients, 25 and 20 of the measured 27 cytokines were significantly elevated (P<0.05) in the Hr-PDR and DME patients, respectively. As compared with no-DR patients, vascular endothelial growth factor was only moderately elevated in DME patients (P>0.05), but significantly elevated in Hr-PDR patients (P<0.05). Interleukin 1 receptor antagonist/interleukin 1b (IL1RA/IL1b) ratio was 13 times higher in DME patients as compared with Hr-PDR group.ConclusionWe demonstrated a simple, safe method of VR sampling. This technique provides a pure, albeit small, vitreous sample for proteomics. IL1RA/IL1b ratio was found to be 13-fold higher in the DME group as compared to the Hr-PDR.

Ischemic Retinopathies: Oxidative Stress and Inflammation

Ischemic retinopathies (IRs), such as retinopathy of prematurity (ROP), diabetic retinopathy (DR), and (in many cases) age-related macular degeneration (AMD), are ocular disorders characterized by an initial phase of microvascular changes that results in ischemia, followed by a second phase of abnormal neovascularization that may culminate into retinal detachment and blindness. IRs are complex retinal conditions in which several factors play a key role during the development of the different pathological stages of the disease. Increasing evidence reveals that oxidative stress and inflammatory processes are important contributors to the pathogenesis of IRs. Despite the beneficial effects of the photocoagulation and anti-VEGF therapy during neovascularization phase, the need to identify novel targets to prevent initial phases of these ocular pathologies is still needed. In this review, we provide an update on the involvement of oxidative stress and inflammation in the progression of IRs and address some therapeutic interventions by using antioxidants and anti-inflammatory agents.

Imaging retinal inflammatory biomarkers after intravitreal steroid and anti-VEGF treatment in diabetic macular oedema

PURPOSE

To evaluate changes of specific retinal imaging biomarkers [intraretinal hyper-reflective retinal spots: HRS ; subfoveal neuroretinal detachment: SND; and increased foveal autofluorescence: IFAF after intravitreal steroid or anti-vascular endothelial growth factor treatment in diabetic macular oedema (DME)] as possible indicators of retinal inflammatory condition.

METHODS

Retrospective analysis of images and clinical charts of 49 eyes (49 patients) with DME treated with intravitreal dexamethasone (dexamethasone, 23 eyes) or intravitreal ranibizumab (ranibizumab, 26 eyes). All patients had fundus colour photograph, spectral domain optical coherence tomography (SD OCT) and fundus autofluorescence (FAF), best-corrected visual acuity (BCVA) and microperimetry recorded before and 1 month after the end of treatment. Central macular thickness (CMT), number of HRS and presence of SND were evaluated by SD OCT. Fundus autofluorescence images were evaluated for area of (IFAF). Retinal sensitivity within 4° and 12° from fovea was quantified by microperimetry. Changes in morphologic and functional parameters were assessed, and correlation was performed by Pearson's correlation.

RESULTS

Best-corrected visual acuity and CMT improved in all patients, (p < 0.05, for both groups). Mean number of HRS decreased after both treatments (p < 0.0001). Subfoveal neuroretinal detachment resolved in 85.7% dexamethasone-treated eyes (p = 0.014) and in 50% ranibizumab-treated eyes (p = 0.025). Mean IFAF area decreased in both groups, (p < 0.0001, for both). A significantly higher decrease in CMT was observed in dexamethasone- versus ranibizumab-treated eyes, (p = 0.032). In dexamethasone group, higher number of HRS at baseline and larger IFAF were correlated with higher increase in retinal sensitivity; eyes with SND at baseline had major decrease in CMT versus those without SND, (p = 0.003).

CONCLUSION

Higher number of HRS, larger area of IFAF and presence of SND may indicate a prevalent inflammatory condition in DME with specific response to targeted treatment.

Diabetic retinopathy: current understanding, mechanisms, and treatment strategies

Diabetic retinopathy (DR) causes significant visual loss on a global scale. Treatments for the vision-threatening complications of diabetic macular edema (DME) and proliferative diabetic retinopathy (PDR) have greatly improved over the past decade. However, additional therapeutic options are needed that take into account pathology associated with vascular, glial, and neuronal components of the diabetic retina. Recent work indicates that diabetes markedly impacts the retinal neurovascular unit and its interdependent vascular, neuronal, glial, and immune cells. This knowledge is leading to identification of new targets and therapeutic strategies for preventing or reversing retinal neuronal dysfunction, vascular leakage, ischemia, and pathologic angiogenesis. These advances, together with approaches embracing the potential of preventative or regenerative medicine, could provide the means to better manage DR, including treatment at earlier stages and more precise tailoring of treatments based on individual patient variations.

Visualization of changes in the foveal avascular zone in both observed and treated diabetic macular edema using optical coherence tomography angiography

BACKGROUND

Central vision loss in diabetic retinopathy is commonly related to diabetic macular edema (DME). The objective of this study was to describe changes between consecutive visits on optical coherence tomography angiography (OCTA) of the foveal avascular zone (FAZ) in eyes with DME.

METHODS

20 eyes from 14 patients with DME were imaged on 2 successive clinic visits separated by at least 1 month. The mean interval between visits was 3.2 months. The only intervention used was intravitreal anti-VEGF in 11 eyes; the others were observed over time without treatment. Two different readers measured FAZ area using a pseudo-automated tool in comparison to a manual tracing tool. Qualitative changes in the appearance of the vasculature surrounding the FAZ were also recorded. The retinal capillary plexus was segmented into deep and superficial plexuses, and FAZ measurements were done on the superficial, deep, and summated plexuses.

RESULTS

Pseudo-automated and manual measurements of FAZ area decreased significantly (p < 0.05) between visits in the deep, superficial, and summated plexuses. Qualitative analysis of vasculature surrounding the FAZ showed that most of the vascular changes (65%) over time were visible in the deep plexus, compared to 30 and 20% in the superficial and summated plexuses, respectively.

CONCLUSIONS

The most significant differences in FAZ size over time were in the summated plexus (p < 0.001), while changes in FAZ appearance were most prominent in the deep plexus. Absolute decrease in FAZ size over visits was largest in the deep plexus. Our results demonstrate that OCTA can effectively be used to measure FAZ area in patients with DME, visualize qualitative changes in retinal vasculature, and visualize the segmentation levels at which these changes can be best appreciated. However, larger studies are needed to evaluate the reproducibility of manual and pseudo-automated measuring techniques.

Ranibizumab in the Treatment of Diabetic Macular Edema: A Review of the Current Status, Unmet Needs, and Emerging Challenges

Diabetic retinopathy (more specifically diabetic macular edema, DME) is the most common cause of loss of vision in the working population in developed countries. Anti-vascular endothelial growth factor (anti-VEGF) agents considerably changed the treatment algorithms and improved prognosis of center-involving DME. Ranibizumab was the first approved anti-VEGF agent that revolutionized DME treatment. The vast increase in the number of patients undergoing intravitreal treatment and the role of anti-VEGF pharmacotherapy as the mainstay of DME treatment have triggered several challenges. Among them, of considerable interest is the quest for an optimal dosing scheme and the search for combination therapies. Although a significant body of research is directed towards other molecules that could potentially be new therapeutic targets, VEGF inhibition is expected to play an important long-term role in the treatment of DME considering the pathogenesis of the disease. Finally, recent studies revealed that ranibizumab may constitute a significant treatment modality in the management of other diabetic vision-threatening complications including proliferative diabetic retinopathy.

Corticosteroid Treatment in Diabetic Macular Edema

Diabetic macular edema is the most common cause of visual impairment in patients with diabetes mellitus. The pathogenesis of macular edema is complex and multifactorial. For many years, laser photocoagulation has been considered the standard therapy for the treatment of diabetic macular edema; however, few patients achieve significant improvements in visual acuity. Today the intravitreal administration of anti-inflammatory or anti-angiogenic agents together with the use of laser photocoagulation represents the standard of care for the treatment of this complication. The intravitreal route of administration minimizes the systemic side effects of corticosteroids. Steroid-related ocular side effects are elevated intraocular pressure and cataract, while injection-related complications include endophthalmitis, vitreous hemorrhage, and retinal detachment. In order to reduce the risks and complications, intravitreal implants have been developed recently to provide sustained release of corticosteroids and reduce repeated injections for the management of diabetic macular edema. In this review, the efficacy, safety, and therapeutic potential of intravitreal corticosteroids in diabetic macular edema are discussed with a review of recent literature.

En Face Doppler Optical Coherence Tomography Measurement of Total Retinal Blood Flow in Diabetic Retinopathy and Diabetic Macular Edema

Importance

Alterations in ocular blood flow play an important role in the pathogenesis and progression of diabetic retinopathy (DR). However, the measurement of retinal blood flow in clinical studies has been challenging. En face Doppler optical coherence tomography (OCT) provides an effective method for measuring total retinal blood flow (TRBF) in the clinic.

Objective

To investigate TRBF in eyes with DR of varying severity, with or without diabetic macular edema (DME), using en face Doppler OCT.

Design, Setting, and Participants

This was a cross-sectional study conducted from May 23, 2014, to January 11, 2016, which analyzed 41 eyes with DR from 31 diabetic patients, 20 eyes without DR from 11 diabetic patients, and 16 eyes from 12 healthy age-matched controls, all at the New England Eye Center in Boston, Massachusetts.

Main Outcomes and Measures

Participants were imaged with a high-speed, swept-source OCT prototype at 1050-nm wavelength using repeated en face Doppler OCT raster scans, comprising 600 × 80 axial scans and covering a 1.5 × 2-mm2 area centered at the optic disc. The TRBF was automatically calculated using custom Matlab software.

Results

This study included 41 eyes with DR from 31 diabetic patients (mean [SD] age, 62.8 [13.4] years; 12 were female patients), 20 eyes without DR from 11 diabetic patients (mean [SD] age, 58.8 [10.1] years; 5 were female patients), and 16 eyes from 12 healthy age-matched controls (mean [SD] age, 57.9 [8.1] years; 8 were female participants). The mean (SD) TRBF was 28.0 (8.5) µL/min in the eyes with DME, 48.8 (13.4) µL/min in the eyes with DR but without DME, 40.1 (7.7) µL/min in the diabetic eyes without retinopathy, and 44.4 (8.3) µL/min in age-matched healthy eyes. A difference in TRBF between the eyes with DME that were treated and the eyes with DME that were not treated was not identified. The TRBF was consistently low in the eyes with DME regardless of DR severity. The eyes with moderate nonproliferative DR but without DME exhibited a wide range of TRBF from 31.1 to 75.0 µL/min, with the distribution being highly skewed.

Conclusions and Relevance

High-speed en face Doppler OCT can measure TRBF in healthy and diabetic eyes. Diabetic eyes with DME exhibited lower TRBF than healthy eyes (P ≤ .001). Further longitudinal studies of TRBF in eyes with DR would be helpful to determine whether reduced TRBF is a risk factor for DME.

Malathion increases apoptotic cell death by inducing lysosomal membrane permeabilization in N2a neuroblastoma cells: a model for neurodegeneration in Alzheimer's disease

Malathion is an organophosphate with severe neurotoxic effects. Upon acute exposure, malathion initially enhances cholinergic activity by inhibition of acetylcholinesterase, which is its major pathological mechanism. Malathion also induces non-cholinergic neuronal cell death in neurodegenerative conditions; the associated molecular mechanism is not well-characterized. To investigate the molecular mechanism of malathion-induced cell death, N2a mouse neuroblastoma cells were exposed to malathion and cell death-related parameters were examined. Malathion reduced cell viability mainly by apoptosis through mitochondrial dysfunction in N2a cells, as judged by an increase in the level of the pro-apoptotic protein Bax and decrease in the levels of the anti-apoptotic proteins p-Akt and Bcl2, resulting in cytochrome c release and caspase-dependent DNA fragmentation and condensation. Malathion treatment also induced autophagy and lysosomal membrane permeabilization (LMP) in N2a cells. LMP caused a lessening of autophagic flux via inhibition of lysosomal fusion with the autophagosome. LMP-induced cathepsin B release and its proteolytic effect may intensify apoptotic insults. Moreover, malathion-exposed N2a cells showed a marked reduction in the levels of the neuronal marker proteins vascular endothelial growth factor and heart fatty acid binding protein 3, along with diminished neuritogenesis in N2a cells and nerve growth factor secretion in C6 glioma cells. Our data suggest that the non-cholinergic effect of malathion may be mediated by apoptotic cell death via LMP induction in N2a cells. Malathion-treated N2a cells can be utilized as an in vitro model system to screen natural and new chemical drug candidates for neurodegenerative diseases such as Alzheimer’s disease.

Preparation of dexamethasone ophthalmic implants: a comparative study of in vitro release profiles

Diseases affecting the posterior segment of the eye are the most common cause of visual disorders in industrialized countries. This scenario has encouraged the development of new treatment modalities for these diseases, such as drug loaded implants with prolonged drug release. The aim of the present work was to create a polymeric based biodegradable ophthalmic implant for the delivery of dexamethasone. For this purpose, we prepared and compared the in vitro release profiles of dexamethasone ophthalmic implants produced by two methods: melting casting and solvent casting. The type of the biodegradable polymer used - poly (ɛ-caprolactone) (PCL) and poly(lactic acid) (PLA); the drug loading (10% and 25%, w/w), the molecular weight of PCL (37 kDa and 14 kDa) and the form of the drug (dexamethasone and dexamethasone disodium phosphate) were also investigated. The results show that the preparation method has little influence on the obtained release profiles, being the type of polymer the most significant factor affecting the release profiles; nonetheless, a better distribution of dexamethasone was obtained for the devices prepared by melting casting.

Anti-VEGF treatment of diabetic macular edema in clinical practice: effectiveness and patterns of use (ECHO Study Report 1)

Purpose

To evaluate the efficacy, safety, and injection frequency of vascular endothelial growth factor (VEGF) inhibitors as used in clinical practice for the treatment of diabetic macular edema.

Methods

Multicenter (10 sites), retrospective chart review in patients (n=156) who received ≥3 anti-VEGF injections. Data collected for ≥6 months after the first injection included Snellen best-corrected visual acuity (BCVA) and central retinal thickness (CRT) by time-domain or spectral-domain optical coherence tomography (TD-OCT or SD-OCT).

Results

Mean number of anti-VEGF injections (627 bevacizumab, 594 ranibizumab, 1 aflibercept) was 5.8 (year 1), 5.0 (year 2), and 3.4 (year 3). Percentage of patients with BCVA of 20/40 or better and CRT ≤250 μm on TD-OCT or ≤300 μm on SD-OCT at the same visit (primary endpoint) ranged from 16.4% to 38.9% after the first 10 injections; 51.9%–62.3% achieved ≥20/40 BCVA and 26.2%–48.0% met CRT criteria. Therapy was well tolerated with 19 treatment-related adverse events (all ocular) reported.

Conclusion

Anti-VEGF injections were administered less frequently and were less effective than those in the ranibizumab registration trials. After each of the first 9 injections, <25% of patients achieved both BCVA of 20/40 or better and a dry macula. A substantial proportion of patients are suboptimal responders to anti-VEGF therapy; these patients may be candidates for other therapies, including intravitreal corticosteroid and laser therapy.

Adenosine Deaminase-2-Induced Hyperpermeability in Human Retinal Vascular Endothelial Cells Is Suppressed by MicroRNA-146b-3p

PURPOSE

We recently demonstrated that adenosine deaminase-2 (ADA2) contributes to diabetic retinopathy (DR) via up-regulating the production of inflammatory cytokines in macrophages. Also, microRNA (miR)-146b-3p has the ability to inhibit ADA2. The goal of this study was to investigate the potential role of ADA2 and therapeutic benefit of miR-146b-3p in retinal inflammation and endothelial barrier dysfunction during diabetes.

METHODS

Adenosine deaminase-2 activity was determined by colorimetric method in diabetic human vitreous. Human monocyte cell line U937 was differentiated into macrophages and then treated with amadori glycated albumin (AGA), and conditioned medium (CM) was used to assess the changes in ADA2 activity and TNF-α and IL-6 levels by ELISA. Also, macrophages were transfected with miR-146b-3p before treatment with AGA. Permeability of human retinal endothelial cells (hRECs) was assessed by electric cell-substrate impedance sensing (ECIS) after treatment with macrophage CM. Zonula occludens (ZO)-1 was examined by immuno-fluorescence in hRECs. Leukocyte adhesion was assessed in hRECs by measuring myeloperoxidase (MPO) activity and intercellular adhesion molecule-1 (ICAM-1) expression.

RESULTS

Adenosine deaminase-2 activity was significantly increased in diabetic human vitreous. ADA2 activity and TNF-α and IL-6 levels were significantly increased in human macrophages by AGA treatment. Amadori glycated albumin-treated macrophage CM significantly increased hREC permeability, disrupted ZO-1 pattern, and increased leukocyte adhesion to hRECs through up-regulating ICAM-1. All these changes were reversed by miR-146b-3p.

CONCLUSIONS

Adenosine deaminase-2 is implicated in breakdown of the blood-retinal barrier (BRB) in DR through macrophages-derived cytokines. Therefore, inhibition of ADA2 by miR-146b-3p might be a useful tool to preserve BRB function in DR.

Comparison of Cysts in Red and Green Images for Diabetic Macular Edema

PURPOSE

To investigate whether cysts in diabetic macular edema are better visualized in the red channel of color fundus camera images, as compared with the green channel, because color fundus camera screening methods that emphasize short-wavelength light may miss cysts in patients with dark fundi or changes to outer blood retinal barrier.

METHODS

Fundus images for diabetic retinopathy photoscreening were acquired for a study with Aeon Imaging, EyePACS, University of California Berkeley, and Indiana University. There were 2047 underserved, adult diabetic patients, of whom over 90% self-identified as a racial/ethnic identify other than non-Hispanic white. Color fundus images at nominally 45 degrees were acquired with a Canon Cr-DGi non-mydriatic camera (Tokyo, Japan) then graded by an EyePACS certified grader. From the 148 patients graded to have clinically significant macular edema by the presence of hard exudates in the central 1500 μm of the fovea, we evaluated macular cysts in 13 patients with cystoid macular edema. Age ranged from 33 to 68 years. Color fundus images were split into red, green, and blue channels with custom Matlab software (Mathworks, Natick, MA). The diameter of a cyst or confluent cysts was quantified in the red-channel and green-channel images separately.

RESULTS

Cyst identification gave complete agreement between red-channel images and the standard full-color images. This was not the case for green-channel images, which did not expose cysts visible with standard full-color images in five cases, who had dark fundi. Cysts appeared more numerous and covered a larger area in the red channel (733 ± 604 μm) than in the green channel (349 ± 433 μm, P < .006).

CONCLUSIONS

Cysts may be underdetected with the present fundus camera methods, particularly when short-wavelength light is emphasized or in patients with dark fundi. Longer wavelength techniques may improve the detection of cysts and provide more information concerning the early stages of diabetic macular edema or the outer blood retinal barrier.

Bromfenac Eyedrops in the Treatment of Diabetic Macular Edema: A Pilot Study

Purpose

To evaluate the efficacy and safety of topical bromfenac in patients with newly diagnosed diabetic macular edema (DME).

Methods

In this pilot study including 17 patients with monocular, newly diagnosed DME, diagnosis of DME was established by the detection of retinal thickening at or within 500 μm of the center of the macula on ophthalmoscopic examination, according to the Early Treatment Diabetic Retinopathy Study classification. Central macular thickness (CMT) was determined by optical coherence tomography. Bromfenac sodium hydrate 0.9 mg/mL eyedrops were administered in the affected eye twice daily for 30 days. Primary endpoints were changes in best-corrected visual acuity (BCVA) and CMT at the end of therapy.

Results

Topical bromfenac significantly reduced mean CMT, from 465.41 ± 118.47 μm at baseline to 388.88 ± 152.63 μm posttreatment (p = 0.02). There was no significant change in BCVA and differences in mean macular volume fell just short of statistical significance (p = 0.06). Treatment was well-tolerated, and there were no topical or systemic side effects.

Conclusions

Topical bromfenac twice daily may play a role in the reduction of DME. These preliminary results warrant further larger multicenter studies to confirm our findings and establish whether topical bromfenac may be of long-term benefit in the treatment of DME.

Vascular Endothelial Growth Factor and Diabetic Retinal Disease

Diabetic retinal disease remains a leading cause of blindness among working-aged adults around the world. Until this decade, laser photocoagulation for both proliferative diabetic retinopathy and diabetic macular edema had been the standard of care for millions of patients. The introduction of vascular endothelial growth factor inhibitors (anti-VEGF) and subsequent clinical trials demonstrating their efficacy for treatment of diabetic eye disease have established a new standard in treatment of center-involved diabetic macular edema that is highly specific to the pathologic process and highly effective in preserving and improving vision. This review focuses on clinically relevant developments that led to the shift from focal/grid laser photocoagulation to anti-VEGF injections in the treatment of center-involved diabetic macular edema (DME), with an overview of the disease pathophysiology, clinical disease course, and available anti-VEGF agents. This article also reviews the scientific evidence exploring the use of anti-VEGF agents in nonproliferative and proliferative diabetic retinopathy.

Diabetic Macular Edema

Diabetic macular edema (DME), one the most prevalent causes of visual loss in industrialized countries, may be diagnosed at any stage of diabetic retinopathy. The diagnosis, treatment, and follow up of DME have become straightforward with recent developments in fundus imaging, such as optical coherence tomography. Laser photocoagulation, intravitreal injections, and pars plana vitrectomy surgery are the current treatment modalities; however, the positive effects of currently available intravitreally injected agents are temporary. At this point, further treatment choices are needed for a permanent effect.

The Impact of Bariatric Surgery on Diabetic Retinopathy: A Systematic Review and Meta-Analysis

BACKGROUND

Significant reductions in glucose control immediately post bariatric surgery in patients with longstanding poor glycemic control can lead to the paradoxical progression of diabetic retinopathy (DR) in susceptible individuals. Bariatric surgery results in dramatic and immediate diabetic control postoperatively. We aimed to systematically review the literature to assess the effect of bariatric surgery on DR.

METHODS

A comprehensive search of electronic databases (e.g., MEDLINE, EMBASE, SCOPUS, Web of Science, and the Cochrane Library) was completed. All randomized controlled trials, non-randomized comparison study, and case series were included. Inclusion criteria included English-speaking studies, enrolling ≥ 5 patients, and contained ophthalmological data on outcome of DR pre- and post bariatric surgery. Two independently reviewers screened abstracts, reviewed full text versions of all studies classified, and extracted data. All comparison studies included in the meta-analysis were assessed independently by two reviewers for methodological quality using the Cochrane Risk of Bias (RoB) tools. Disagreements were resolved by re-extraction, or third-party adjudication. Where possible and appropriate, a meta-analysis was conducted.

RESULTS

A total of 277 studies were identified using our search criteria for screening. Four primary studies (n = 148 patients) met our inclusion criteria and were included in the systematic review. These included no randomized controlled trials and four non-randomized case series. Patients with no preoperative DR (n = 80), following bariatric surgery, an average of 92.5 ± 7.4 % remained disease free, while 7.5 ± 7.4 % of patients progressed to DR. Patients with diabetic retinopathy preoperatively (n = 68), following bariatric surgery, an average of 57.4 ± 18.5 % of patients had no change, 23.5 ± 18.7 % of patients had progression, and 19.2 ± 2.9 % of patients had improvement in their disease.

CONCLUSIONS

Progression of diabetic retinopathy is a significant issue postoperatively following bariatric surgery. Patients with a diagnosis of DR prior to surgery are at increased risk of further progression in their disease and should receive adequate counseling and evaluation prior to undergoing a surgical procedure. However, the few primary studies in this systematic review limit any conclusion. Further studies are needed to further evaluate these results.

[Association between visual improvement after photocoagulation and the use of angiotensin converting enzyme inhibitors in diabetic macular oedema]

BACKGROUND

Angiotensin converting enzyme inhibitors are effective in delaying the progression of diabetic retinopathy. It is unknown if their use is associated with a better visual outcome in patients with diabetic macular oedema.

MATERIAL AND METHODS

A non-experimental, comparative, longitudinal and retrospective study was performed on patients with diabetic macular oedema treated by focal photocoagulation, and with systemic arterial hypertension treated with angiotensin converting enzyme inhibitors (Group 1), and without hypertension (Group 2). The dependent variable was the proportion with visual improvement, operatively defined as the gain of one or more lines of vision three weeks after photocoagulation. The independent variable was the use of angiotensin converting enzyme inhibitors. The proportion of eyes with visual improvement after treatment was compared between groups using the Chi squared (χ(2)) test.

RESULTS

A total of 33 eyes (51.6%) were assigned to group 1, and 31 (48.2%), to group 2. The mean of visual acuity improved after three weeks, compared with baseline (p=0.002). The proportion of eyes with visual improvement did not differ between patients treated with angiotensin converting enzyme inhibitors (45.5%) and those that did not use them (51.6%, p=0.4).

CONCLUSIONS

There was no statistical difference in the proportion of eyes with visual improvement between patients treated with angiotensin converting enzyme inhibitors and in those where they were not used. There is no support for the inhibition of angiotensin II in addition to photocoagulation for improving the outcome in patients with diabetic macular oedema.

Treatment strategies for refractory diabetic macular edema: switching anti-VEGF treatments, adopting corticosteroid-based treatments, and combination therapy

INTRODUCTION

The pathophysiology of diabetic macular edema (DME) is complex, involving vascular endothelial growth factor (VEGF) and other inflammatory mediators. DME is currently treated first-line with intravitreal anti-VEGF treatments, though some cases are refractory to multiple anti-VEGF treatments.

AREAS COVERED

This article examines the evolution of treatment practices for DME, with discussion of the recent studies that guide treatment for refractory cases of DME. A literature search was performed using the following terms: anti-VEGF, DME, aflibercept, bevacizumab, ranibizumab, refractory macular edema, and VEGF.

EXPERT OPINION

Focal extrafoveal DME may be treated first-line with laser. In patients with center-involving DME and only mild vision loss, consider starting treatment with bevacizumab, especially when cost is an issue, whereas aflibercept may be considered more strongly in patients with moderate visual loss or worse. There are no standard protocols that define 'treatment failure,' but several studies have reported that switching from bevacizumab to either ranibizumab or aflibercept will result in further reduction of CSFT and improvement in BCVA. Further study with prospective randomized trials is warranted to validate these findings. Switching to intravitreal corticosteroids may be of particular benefit to pseudophakic patients. Anti-VEGF combination with sustained-release corticosteroids also appears promising for refractory DME.

Sustained intraocular VEGF neutralization results in retinal neurodegeneration in the Ins2(Akita) diabetic mouse

Current therapies that target vascular endothelial growth factor (VEGF) have become a mainstream therapy for the management of diabetic macular oedema. The treatment involves monthly repeated intravitreal injections of VEGF inhibitors. VEGF is an important growth factor for many retinal cells, including different types of neurons. In this study, we investigated the adverse effect of multiple intravitreal anti-VEGF injections (200 ng/μl/eye anti-mouse VEGF164, once every 2 weeks totalling 5-6 injections) to retinal neurons in Ins2(Akita) diabetic mice. Funduscopic examination revealed the development of cotton wool spot-like lesions in anti-VEGF treated Ins2(Akita) mice after 5 injections. Histological investigation showed focal swellings of retinal nerve fibres with neurofilament disruption. Furthermore, anti-VEGF-treated Ins2(Akita) mice exhibited impaired electroretinographic responses, characterized by reduced scotopic a- and b-wave and oscillatory potentials. Immunofluorescent staining revealed impairment of photoreceptors, disruptions of synaptic structures and loss of amacrine and retinal ganglion cells in anti-VEGF treated Ins2(Akita) mice. Anti-VEGF-treated WT mice also presented mild amacrine and ganglion cell death, but no overt abnormalities in photoreceptors and synaptic structures. At the vascular level, exacerbated albumin leakage was observed in anti-VEGF injected diabetic mice. Our results suggest that sustained intraocular VEGF neutralization induces retinal neurodegeneration and vascular damage in the diabetic eye.

Correlation of Vitreous Vascular Endothelial Growth Factor and Uric Acid Concentration Using Optical Coherence Tomography in Diabetic Macular Edema

Purpose. We investigated two factors linked to diabetic macular edema (DME), vitreous and serum levels of vascular endothelial growth factor (VEGF) and uric acid (UA) in patients with DME, and compared the results with changes in optical coherence tomography (OCT) and visual acuity (VA). Methods. A prospective study of 29 eyes, 16 cystoid DME and nonproliferative diabetic retinopathy (DR) and 13 nondiabetic controls. Biochemical analysis of vitreous and serum samples was performed and OCT scans were graded according to central retinal thickness (CRT), cube volume (CV), cube average thickness (CAT), and serous retinal detachment (SRD). Results. In DME group, intravitreal concentrations of VEGF (p < 0.001), UA (p = 0.038), and total protein (p < 0.001) were significantly higher than in control group. In DME subjects, intravitreal UA correlated significantly with intravitreal VEGF (ƍ = 0.559, p = 0.03) but not with total vitreous protein and serum UA. Increased intravitreal VEGF in DME group correlated with increase in CV (ƍ = 0.515/p = 0.041). None of the OCT parameters correlated with the VA. Conclusions. The results suggest that the CV might be assessor of anti-VEGF therapy efficacy. Second, apart from VEGF, the role of UA in the pathogenesis and progression of DR should be considered.

Efficacy of dexamethasone versus bevacizumab on regression of hard exudates in diabetic maculopathy: data from the BEVORDEX randomised clinical trial

OBJECTIVE

To report the effect of bevacizumab versus dexamethasone on hard exudates (HEX) in diabetic macular oedema (DME).

DESIGN

Post hoc analysis of 24-month data from the Randomised clinical trial of BEVacizumab OR DEXamethasone for diabetic macular oedema (BEVORDEX) phase 2 multicentre randomised clinical trial. Eyes with centre-involving DME resistant to or unlikely to benefit from macular laser therapy were included. Eyes were randomly assigned to bevacizumab every 4 weeks or Ozurdex dexamethasone implant (DEX) every 16 weeks, both as required. The 68 eyes from 48 patients that completed 24-month follow-up were analysed. Two masked graders assessed extent and location of HEX on baseline, 12-month and 24-month foveal-centred colour fundus photographs using validated grading software.

RESULTS

Macular HEX was present in 60% of study eyes. Of these, 21 eyes were treated with DEX and 20 eyes with bevacizumab. Both treatments led to reduction in area of macular HEX at 12 months and 24 months. There was greater regression of HEX from the foveal centre in DEX-treated eyes (median change +890 µm, IQR=1040 µm) than bevacizumab-treated eyes (median change +7.0 µm, IQR=590 µm) at 12 months (p=0.04) but the difference was no longer statistically significant (p=0.10) by 24 months (DEX +1400 µm, IQR=1590 µm; bevacizumab +20 µm, IQR=2680 µm). Reassuringly, no study eye developed HEX at the foveal centre, a visually devastating consequence of diabetic maculopathy.

CONCLUSIONS

Bevacizumab and DEX were effective in reducing area of HEX in eyes with DME. DEX provided more rapid regression of HEX from the foveal centre although bevacizumab-treated eyes started to catch up by 24 months. Distance from the foveal centre as well as total area of macular HEX should be assessed when evaluating treatments for foveal-threatening HEX.

TRIAL REGISTRATION NUMBER

NCT01298076; Post-results.

[Lack of correlation between retinal variables before treatment and poor functional response after focal photocoagulation in diabetic macular oedema]

BACKGROUND

Although photocoagulation reduces the incidence of moderate visual loss in eyes with focal diabetic macular oedema, some eyes may lose some vision after treatment. The proportion of eyes with poor functional response after photocoagulation, and whether any retinal variable is associated with this, is unknown.

OBJECTIVE

To determine the proportion of eyes with diabetic macular oedema that have a poor functional response after focal photocoagulation, and their associated features.

MATERIAL AND METHODS

A non-experimental, longitudinal, comparative and retrospective study was conducted. The proportion and 95% confidence intervals (CI) of diabetics with macular oedema that had a poor functional response after focal photocoagulation (any visual loss after 6 weeks) were identified. The means of retinal variables before treatment were compared between eyes with and without a poor functional response using the Student t test for independent means.

RESULTS

The study included 115 eyes of patients aged 59.3 (SD 9.24) years. Visual acuity was greater than or equal to 0.5 in 63 eyes (54.8%). A total of 33 eyes had a poor functional response after photocoagulation (28.7%, 95% CI: 13.3 to 44.1). The comparison between retinal variables and visual acuity before treatment did not show any differences between eyes with or without a poor functional response and eyes.

CONCLUSION

Retinal thickening and visual acuity improved or did not change in 71.3% of eyes with diabetic macular oedema with a single photocoagulation procedure. Retinal variables that are usually evaluated were unable to identify the remaining 28.7%, which could lose vision after that treatment, and would require additional interventions.

Macular auto-fluorescence is a follow-up parameter for cystoids macular edema

This study aimed to evaluate if macular autofluorescence (MAF) is a valuable, non-invasive follow-up parameter for cystoid macular edema. A total of 71 eyes (71 cases) with cystoid macular edema (CME) were included in the study. Macular pigment (MP) was evaluated using HRA2 (infrared) IF and FA models. The density of MP was graded into three categories: without, partial, and normal amount of MP. A comparison was made between the baseline (before the first administration) level and at the fourth month, following three consecutive intravitreal lucentis injections every month. The morphology and distribution of MAF, and the density and distribution of MP were regarded as the main outcome measures. At the baseline visit, all eyes with CME had petaloid/irregular-shaped MAF in the macular area (100%). No MAF was detected in the control eyes (0). There was significant difference in MAF between the CME and normal groups (P=0.000). At the fourth monthly visit, normal levels of MP density without MAF was detected in 68 eyes (95.8%) with the best corrected spectacular visual acuity increasing to at least 1 line accordingly. We conclude that macular MAF can be used as a follow-up parameter for patients with CME. MP and MAF can indirectly reflect the fovea cone function.

Anti-VEGF treatment for myopic choroid neovascularization: from molecular characterization to update on clinical application

Choroidal neovascularization (CNV) secondary to pathologic myopia has a very high incidence in global, especially in Asian, populations. It is a common cause of irreversible central vision loss, and severely affects the quality of life in the patients with pathologic myopia. The traditional therapeutic modalities for CNV secondary to pathologic myopia include thermal laser photocoagulation, surgical management, transpupillary thermotherapy, and photodynamic therapy with verteporfin. However, the long-term outcomes of these modalities are disappointing. Recently, intravitreal administration of anti-VEGF biological agents, including bevacizumab, ranibizumab, pegaptanib, aflibercept, and conbercept, has demonstrated promising outcomes for this ocular disease. The anti-VEGF regimens are more effective on improving visual acuity, reducing central fundus thickness and central retina thickness than the traditional modalities. These anti-VEGF agents thus hold the potential to become the first-line medicine for treatment of CNV secondary to pathologic myopia. This review follows the trend of “from bench to bedside”, initially discussing the pathogenesis of myopic CNV, delineating the molecular structures and mechanisms of action of the currently available anti-VEGF drugs, and then systematically comparing the up to date clinical applications as well as the efficacy and safety of the anti-VEGF drugs to the CNV secondary to pathologic myopia.

Nanocarriers for treatment of ocular neovascularization in the back of the eye: new vehicles for ophthalmic drug delivery

Pathologic neovascularization of the retina is a major cause of substantial and irreversible loss of vision. Drugs are difficult to deliver to the lesions in the back of the eye and this is a major obstacle for the therapeutics. Current pharmacological approach involves an intravitreal injection of anti-VEGF agents to prevent aberrant growth of blood vessels, but it has limitations including therapeutic efficacy and side-effects associated with systemic exposure and invasive surgery. Nanotechnology provides novel opportunities to overcome the limitations of conventional delivery system to reach the back of the eye through fabrication of nanostructures capable of encapsulating and delivering small molecules. This review article introduces various forms of nanocarrier that can be adopted by ocular drug delivery systems to improve current therapy. The application of nanotechnology in medicine brings new hope for ocular drug delivery in the back of the eye to manage the major causes of blindness associated with ocular neovascularization.

Common Sequence Variation in the VEGFC Gene Is Associated with Diabetic Retinopathy and Diabetic Macular Edema

PURPOSE

To investigate associations between single nucleotide polymorphisms (SNPs) in the VEGFC gene and the development of diabetic retinopathy (DR) in white patients with type 1 diabetes mellitus (T1DM) or type 2 diabetes mellitus (T2DM).

DESIGN

Cross-sectional, case control study.

PARTICIPANTS

White patients with T1DM or T2DM (n = 2899) were recruited from ophthalmology and endocrine clinics in Australia and the United Kingdom. Patients with T2DM were required to have diabetes mellitus (DM) for at least 5 years and be receiving oral hypoglycemic treatment or insulin.

METHODS

Participants were categorized according to their worst-ever DR grading, as having "no DR" (no history of nonproliferative DR [NPDR], proliferative DR [PDR], or diabetic macular edema [DME]) or "any DR" (further subclassified as NPDR or PDR, without or with DME). Clinical characteristics, glycemic control (hemoglobin A1c [HbA1c]), and presence of diabetic complications were determined at recruitment. Genotyping was performed for 13 VEGFC tag SNPs.

MAIN OUTCOME MEASURES

Odds ratios (ORs) were determined for associations with DR of VEGFC tag SNPs, individually and within haplotypes. Logistic regression was used to adjust for clinical covariates, including DM type, age, sex, DM duration, hypertension, nephropathy, HbA1c, and smoking.

RESULTS

Participants with DM but "no DR" (n = 980) were compared with 1919 participants with DM and "any DR." Three VEGFC SNPs were associated with DR after logistic regression: rs17697419 (P = 0.001; OR, 0.67; confidence interval [CI], 0.52-0.85), rs17697515 (P = 0.001; OR, 0.62; CI, 0.47-0.81), and rs2333526 (P = 0.005; OR, 0.69; CI, 0.54-0.90). rs17697515 Was also specifically associated with DME in those with T2DM (P = 0.004; OR, 0.53; CI, 0.35-0.82). Haplotype analysis revealed 2 significantly associated haplotypes, both protective against DR development.

CONCLUSIONS

Significant associations were found between VEGFC tag SNPs (individually and within haplotypes) and the presence of any DR or DME in white participants with T1DM and T2DM.

Exercise training prevents increased intraocular pressure and sympathetic vascular modulation in an experimental model of metabolic syndrome

The present study aimed to study the effects of exercise training (ET) performed by rats on a 10-week high-fructose diet on metabolic, hemodynamic, and autonomic changes, as well as intraocular pressure (IOP). Male Wistar rats receiving fructose overload in drinking water (100 g/L) were concomitantly trained on a treadmill for 10 weeks (FT group) or kept sedentary (F group), and a control group (C) was kept in normal laboratory conditions. The metabolic evaluation comprised the Lee index, glycemia, and insulin tolerance test (KITT). Arterial pressure (AP) was measured directly, and systolic AP variability was performed to determine peripheral autonomic modulation. ET attenuated impaired metabolic parameters, AP, IOP, and ocular perfusion pressure (OPP) induced by fructose overload (FT vs F). The increase in peripheral sympathetic modulation in F rats, demonstrated by systolic AP variance and low frequency (LF) band (F: 37±2, 6.6±0.3 vs C: 26±3, 3.6±0.5 mmHg²), was prevented by ET (FT: 29±3, 3.4±0.7 mmHg²). Positive correlations were found between the LF band and right IOP (r=0.57, P=0.01) and left IOP (r=0.64, P=0.003). Negative correlations were noted between KITT values and right IOP (r=-0.55, P=0.01) and left IOP (r=-0.62, P=0.005). ET in rats effectively prevented metabolic abnormalities and AP and IOP increases promoted by a high-fructose diet. In addition, ocular benefits triggered by exercise training were associated with peripheral autonomic improvement.

Role of implants in the treatment of diabetic macular edema: focus on the dexamethasone intravitreal implant

Diabetic macular edema (DME) is the leading cause of sight-threatening complication in diabetic patients, and several treatment modalities have been developed and evaluated to treat this pathology. Intravitreal agents, such as anti-vascular endothelial growth factors (anti-VEGF) or corticosteroids, have become more popular in recent years and are widely used for treating DME. Sustained release drugs appear to be mentioned more often nowadays for extending the period of intravitreal activity, and corticosteroids play a key role in inhibiting the inflammatory process in DME. A potent corticosteroid, dexamethasone (Ozurdex(®)), in the form of an intravitreal implant, has been approved for various ocular etiologies among which DME is also one. This review evaluates the role of implants in the treatment of DME, mainly focusing on the dexamethasone intravitreal implant.

Diabetic Retinopathy: Vascular and Inflammatory Disease

Diabetic retinopathy (DR) is the leading cause of visual impairment in the working-age population of the Western world. The pathogenesis of DR is complex and several vascular, inflammatory, and neuronal mechanisms are involved. Inflammation mediates structural and molecular alterations associated with DR. However, the molecular mechanisms underlying the inflammatory pathways associated with DR are not completely characterized. Previous studies indicate that tissue hypoxia and dysregulation of immune responses associated with diabetes mellitus can induce increased expression of numerous vitreous mediators responsible for DR development. Thus, analysis of vitreous humor obtained from diabetic patients has made it possible to identify some of the mediators (cytokines, chemokines, and other factors) responsible for DR pathogenesis. Further studies are needed to better understand the relationship between inflammation and DR. Herein the main vitreous-related factors triggering the occurrence of retinal complication in diabetes are highlighted.