Diabetic retinopathy and the use of laser photocoagulation: is it cost-effective to treat early?

Incidence and risk factors of severe non-proliferative/proliferative diabetic retinopathy: More than a decade follow up in the Tehran Lipids and Glucose Study

AIMS/INTRODUCTION

To examine the incidence rate of severe non-proliferative and proliferative diabetic retinopathy (severe-NPDR/PDR) and determine its potential risk factors.

MATERIALS AND METHODS

The study consisted of 1,169 participants (675 women) with type 2 diabetes mellitus, aged ≥20 years. A trained interviewer collected information about the history of pan-retinal photocoagulation as a result of diabetic retinopathy. Multivariable Cox proportional hazards regression models were applied.

RESULTS

We found 187 cases (126 women) of severe-NPDR/PDR during a median follow-up period of 12.7 years; the corresponding incidence rate was 13.6 per 1,000 person-years. Being overweight (hazard ratio [HR], 95% confidence interval [CI] 0.60, 0.39-0.92) and obese (HR 0.48, 95% CI 0.27-0.83) were associated with lower risk, whereas being smoker (HR 1.75, 95% CI 1.12-2.74), having fasting plasma glucose levels 7.22-10.0 mmol/L (HR 2.81, 95% CI 1.70-4.62), fasting plasma glucose ≥10 mmol/L (HR 5.87, 95% CI 3.67-9.41), taking glucose-lowering medications (HR 2.58, 95% CI 1.87-3.56), prehypertension status (HR 1.65, 95% CI 1.05-2.58) and newly diagnosed hypertension (HR 1.96, 95% CI 1.06-3.65) increased the risk of severe-NPDR/PDR. Among newly diagnosed diabetes patients, being male was associated with a 59% lower risk of severe-NPDR/PDR (HR 0.41, 95% CI 0.21-0.79). Furthermore, patients who had an intermediate level of education (6-12 years) had a higher risk of developing PDR (HR 1.86, 95% CI 1.05-3.30) compared with those who had <6 years of education.

CONCLUSIONS

Among Iranians with type 2 diabetes mellitus, 1.36% developed severe-NPDR/PDR annually. Normal bodyweight, being a smoker, out of target fasting plasma glucose level, prehypertension and newly diagnosed hypertension status were independent risk factors of severe-NPDR/PDR. Regarding the sight-threatening entity of advanced diabetic retinopathy, the multicomponent strategy to control diabetes, abstinence of smoking and tight control of blood pressure should be considered.

Update on Management of Non-proliferative Diabetic Retinopathy without Diabetic Macular Edema; Is There a Paradigm Shift?

Diabetic retinopathy (DR) is the major cause of visual impairment and blindness in the working-age population. Conventional management for nonproliferative diabetic retinopathy (NPDR) without diabetic macular edema (DME) is derived from the findings of the Early Treatment Diabetic Retinopathy Study (ETDRS). Although the ETDRS protocol basically includes observation, selected cases of severe NPDR may undergo scatter laser photocoagulation. Post-hoc analysis of recent trials has shown that patients with NPDR receiving intravitreal anti-vascular endothelial growth factor (anti-VEGF) for DME would experience improvement in the DR severity scale (DRSS). In addition, recent randomized trials (PANORAMA and Protocol W) have revealed that early intervention with intravitreal aflibercept in eyes with moderately severe to severe NPDR is associated with significant improvement in DRSS and reduced vision-threatening complications of DR. Based on recent studies, it seems that the therapeutic approach to NPDR may undergo a substantial change and a paradigm shift toward considering early intervention with the administration of intravitreal anti-VEGF injections. However, the long-term results and the duration of adherence to anti-VEGF therapy for eyes with NPDR are not yet defined. It is also not apparent whether improvement in DRSS is a true disease modification. Studies showed that DRSS improvement is not associated with retinal reperfusion. In addition, DRCR.net Protocol W showed no visual acuity benefit with the early intravitreal aflibercept injection in moderate to severe NPDR as compared with performing observation plus intravitreal aflibercept applied only after progression to proliferative DR or vision-impairing DME. The cost-benefit ratio is also a challenge. Herein, we look at different aspects of early anti-VEGF application and discuss its pros and cons in the process of treating NPDR.

Cyanidin-3-o-glucoside (C3G) inhibits vascular leakage regulated by microglial activation in early diabetic retinopathy and neovascularization in advanced diabetic retinopathy

Cyanidin-3-O-glucoside (C3G) is a kind of anthocyanin which shows strong anti-inflammation, anti-tumor and anti-oxidant properties. This paper was designed to explore the potential effects of C3G on diabetic retinopathy (DR). C57BL/6 mice were administrated with streptozotocin (STZ) or vehicle control for the establishment of diabetic models. To simulate hyperglycemia and hypoxia, D-glucose (30 mM) and CoCl₂ (200 μm/l) were utilized to treat HRECs, respectively. The migration, invasion, inflammation and tube formation abilities of cells were evaluated with the adoption of wound healing, transwell, ELISA and tube formation assays, respectively. Besides, immunofluorescence staining was utilized to detect proliferation and retinal vessels. Evans blue permeation assay were performed to evaluate the vascular leakage in DR mice. Moreover, western blot and qPCR were used to quantify the mRNA and protein expressions of ionized calcium-binding adapter molecule (Iba)-1 and tight junction proteins. Results showed that C3G alleviated the inflammation, microglial activation and angiogenesis in DR mice. Moreover, the proliferation and inflammation of BV2 cells induced by high glucose (HG) were suppressed by C3G. Evans blue permeation assay demonstrated the potency of C3G in attenuating vascular leakage. In addition, C3G suppressed the migration, invasion and angiogenesis of human retinal endothelial cells (HRECs) DR model in vitro.By confirming the role of C3G in inhibiting vascular leakage regulated by microglia activation in early DR and angiogenesis in advanced DR, this study pointed out the potential of C3G as a therapeutic drug for DR management.

Comparing the incidence of major cardiovascular events and severe microvascular complications in patients with type 2 diabetes mellitus: A systematic review and meta-analysis

BACKGROUND

Type 2 diabetes mellitus (T2DM) causes both macrovascular and microvascular complications. However, currently, selection of glycemic measures and their thresholds to diagnose T2DM, and efficacy outcomes in evaluation of anti-diabetic drugs is predominantly informed by the relation of T2DM to microvascular complications. We can be severely mistaken on T2DM by neglecting macrovascular complications which are generally more severe, if they also occur more commonly than microvascular complications.

AIM

To compare the incidence of major cardiovascular events (MACEs) and severe microvascular complications (SMICs) in T2DM patients.

METHODS

MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials were searched from inception to September 2017. Cohort studies or trials of T2DM patients aged 18 years or older that reported incidence of both MACEs and SMICs were included. MACEs were defined as nonfatal myocardial infarction and stroke, and cardiovascular death, while SMICs included serious retinopathy, nephropathy and diabetic disorder. The relative risk (RR) was estimated as the incidence of MACEs divided by that of SMICs in same patients and combined with meta-analysis in a random-effect model.

RESULTS

Twelve studies with a total of 16 cohorts and 387376 patients were included, and the combined RR was 2.02 (95%CI: 1.46–2.79). The higher incidence of MACEs remained in various subgroup and sensitivity analyses.

CONCLUSION

Patients with T2DM are much more likely to develop MACEs than SMICs. By taking more serious consequences and relatively higher incidence into consideration, macrovascular complications deserve more emphasis in developing the diagnostic criteria of T2DM and in evaluating the efficacy of anti-diabetic drugs.

Spermine oxidase: A promising therapeutic target for neurodegeneration in diabetic retinopathy

Diabetic Retinopathy (DR), is a significant public health issue and the leading cause of blindness in working-aged adults worldwide. The vision loss associated with DR affects patients' quality of life and has negative social and psychological effects. In the past, diabetic retinopathy was considered as a vascular disease; however, it is now recognized to be a neuro-vascular disease of the retina. Current therapies for DR, such as laser photocoagulation and anti-VEGF therapy, treat advanced stages of the disease, particularly the vasculopathy and have adverse side effects. Unavailability of effective treatments to prevent the incidence or progression of DR is a major clinical problem. There is a great need for therapeutic interventions capable of preventing retinal damage in DR patients. A growing body of evidence shows that neurodegeneration is an early event in DR pathogenesis. Therefore, studies of the underlying mechanisms that lead to neurodegeneration are essential for identifying new therapeutic targets in the early stages of DR. Deregulation of the polyamine metabolism is implicated in various neurodegenerative diseases, cancer, renal failure, and diabetes. Spermine Oxidase (SMOX) is a highly inducible enzyme, and its dysregulation can alter polyamine homeostasis. The oxidative products of polyamine metabolism are capable of inducing cell damage and death. The current review provides insight into the SMOX-regulated molecular mechanisms of cellular damage and dysfunction, and its potential as a therapeutic target for diabetic retinopathy. Structural and functional changes in the diabetic retina and the mechanisms leading to neuronal damage (excitotoxicity, loss of neurotrophic factors, oxidative stress, mitochondrial dysfunction etc.) are also summarized in this review. Furthermore, existing therapies and new approaches to neuroprotection are discussed.

Artificial intelligence on diabetic retinopathy diagnosis: an automatic classification method based on grey level co-occurrence matrix and naive Bayesian model

AIM

To develop an automatic tool on screening diabetic retinopathy (DR) from diabetic patients.

METHODS

We extracted textures from eye fundus images of each diabetes subject using grey level co-occurrence matrix method and trained a Bayesian model based on these textures. The receiver operating characteristic (ROC) curve was used to estimate the sensitivity and specificity of the Bayesian model.

RESULTS

A total of 1000 eyes fundus images from diabetic patients in which 298 eyes were diagnosed as DR by two ophthalmologists. The Bayesian model was trained using four extracted textures including contrast, entropy, angular second moment and correlation using a training dataset. The Bayesian model achieved a sensitivity of 0.949 and a specificity of 0.928 in the validation dataset. The area under the ROC curve was 0.938, and the 10-fold cross validation method showed that the average accuracy rate is 93.5%.

CONCLUSION

Textures extracted by grey level co-occurrence can be useful information for DR diagnosis, and a trained Bayesian model based on these textures can be an effective tool for DR screening among diabetic patients.