Automated detection of microaneurysms using scale-adapted blob analysis and semi-supervised learning

Despite several attempts, automated detection of microaneurysm (MA) from digital fundus images still remains to be an open issue. This is due to the subtle nature of MAs against the surrounding tissues. In this paper, the microaneurysm detection problem is modeled as finding interest regions or blobs from an image and an automatic local-scale selection technique is presented. Several scale-adapted region descriptors are introduced to characterize these blob regions. A semi-supervised based learning approach, which requires few manually annotated learning examples, is also proposed to train a classifier which can detect true MAs. The developed system is built using only few manually labeled and a large number of unlabeled retinal color fundus images. The performance of the overall system is evaluated on Retinopathy Online Challenge (ROC) competition database. A competition performance measure (CPM) of 0.364 shows the competitiveness of the proposed system against state-of-the art techniques as well as the applicability of the proposed features to analyze fundus images.

Diagnostic accuracy of direct ophthalmoscopy for detection of diabetic retinopathy using fundus photographs as a reference standard

AIMS

To determine the diagnostic accuracy of direct ophthalmoscopy for the presence and severity of diabetic retinopathy (DR) using fundus photographs as a reference standard.

METHODS

Patients with type 2 diabetes attending the outpatient department (OPD) of a tertiary care diabetes center, from October 2009 to March 2010 were recruited in the study after obtaining signed informed consent. Patients with type 1 diabetes and gestational diabetes or having eye problems were excluded. After checking visual acuity, direct ophthalmoscopy of each eye was done by diabetologist, followed by photography of two fields of retina by fundus camera. DR was graded by a retinal specialist, according to International Diabetic Retinopathy Disease Severity Scale. According to severity, patients with DR were grouped into non-sight threatening diabetic retinopathy (NSTDR) and sight threatening diabetic retinopathy (STDR). Sensitivity and specificity of direct ophthalmoscopy for detection of any retinopathy, NSTDR and STDR was calculated.

RESULTS

A total of 728 eyes were examined by direct ophthalmoscopy as well as fundus photography. Sensitivity (95% CI) of direct ophthalmoscopy for any retinopathy, NSTDR and STDR was found to be 55.67% (50.58-60.78), 37.63% (32.67-42.59) and 68.25% (63.48-73.02) respectively. Whereas, specificity of direct ophthalmoscopy was found to be 76.78% (72.45-81.11), 71.27% (CI: 66.63-75.91) and 90.0% (86.93-93.07) for any retinopathy, NSTDR and STDR respectively.

CONCLUSION

The sensitivity and specificity of direct ophthalmoscopy performed by the diabetologist for the presence and severity of DR was lower compared to the recommended level of sensitivity and specificity of a screening test of DR.

Association of RAGE (p.Gly82Ser) and MnSOD (p.Val16Ala) polymorphisms with diabetic retinopathy in T2DM patients from north India

AIMS

The present study aimed to examine the association of RAGE (p.Gly82Ser) and MnSOD (p.Val16Ala) polymorphisms with diabetic retinopathy (DR) in north Indian T2DM patients.

METHODS

In this case-control association study, 758 T2DM patients were recruited. 446 with retinal neovascularization, microneurysms and hemorrhages were considered as cases (DR) and 312 patients with T2DM and no clinical signs of retinopathy (DNR), were recruited as controls. Genotypes for RAGE (p.Gly82Ser) and MnSOD (p.Val16Ala) polymorphisms were generated by direct sequencing of amplified products.

RESULTS

Genotype distribution of p.Gly82Ser (RAGE) and p.Val16Ala (MnSOD) polymorphisms were significantly different between DR and DNR (p<0.05) whereas distribution of allele frequency did not differ significantly (p>0.05). A significantly higher frequency of homozygous Ser82 genotype in DR patients was detected compared with DNR (2.4% vs 0.64%) for p.Gly82Ser (RAGE) polymorphism whereas there was a higher frequency of homozygous Ala16 genotype for p.Val16Ala (MnSOD) polymorphism in DR patients compared with DNR (22.6% vs 19.3%). Binary logistic analyses showed an association of homozygous recessive genotype Ser82 with DR (OR: 2.63%, 95% CI: 0.16-15.88, p<0.033) for p.Gly82Ser (RAGE) polymorphism. However, we did not find a significant association of p.Val16Ala polymorphism in MnSOD with retinopathy.

CONCLUSIONS

The findings indicate a statistically significant association of p.Gly82Ser polymorphism in RAGE with DR in T2DM patients.

Utility values associated with diabetic retinopathy in Chennai, India

PURPOSE

The aim of this study was to estimate utility values associated with different severity stages of diabetic retinopathy (DR) in India by a direct elicitation method (time-trade off, TTO) and indirectly by questionnaire.

METHODS

People with diabetes aged 40 years and over were recruited from an on-going DR epidemiology study and a laser clinic in Chennai, India. Utility values were elicited using the direct TTO method and indirectly through a validated questionnaire (EQ-5D).

RESULTS

Of 249 participants, 30 had no DR, 73 had non-proliferative DR, 114 had sight-threatening DR, and 32 were blind from DR (bilateral visual acuity <6/60). The mean TTO utility value was 0.73 (standard deviation, SD, 0.31). TTO utility values decreased with increasing severity of DR (p < 0.001) and were significantly lower among participants with sight threatening DR (0.70, SD 0.33) and blindness (0.55, SD 0.24) compared to those with no DR (0.89, SD 0.25) after adjustment for sociodemographic and clinical factors. Blindness from DR was independently associated with a lower EQ-5D utility value. The utility value derived from EQ-5D (0.06) associated with being blind from DR was substantially lower than that of the TTO utility value (0.55).

CONCLUSIONS

This study provides estimates of utility values that can be used in economic evaluations of DR screening strategies in India. The relatively low utility values associated with blindness highlights the importance of screening programs for early detection of the sight-threatening stages to prevent vision loss from DR in this setting.

Phenotypes and biomarkers of diabetic retinopathy. Prog Retin Eye Res. 2014;41:90-111. [PMID: 24680929 DOI: 10.1016/j.preteyeres.2014.03.003]

Diabetic retinopathy (DR) remains a major cause of blindness as the prevalence of diabetes is expected to approximately double globally between 2000 and 2030. DR progresses over time at different rates in different individuals with only a limited number developing significant vision loss due to the two major vision-threatening complications, clinically significant macular edema and proliferative retinopathy. Good metabolic control is important to prevent and delay progression, but whereas some patients escape vision loss even with poor control, others develop vision loss despite good metabolic control. Our research group has been able to identify three different DR phenotypes characterized by different dominant retinal alterations and different risks of progression to vision-threatening complications. Microaneurysm turnover has been validated as a prognostic biomarker of development of clinically significant macular edema, whereas subclinical macular edema identified by OCT and mfERG appear to be also good candidates as organ-specific biomarkers of DR. Hemoglobin A1c remains the only confirmed systemic prognostic biomarker of DR progression. The availability of biomarkers of DR progression and the identification of different phenotypes of DR with different risks for development of vision-threatening complications offers new perspectives for understanding DR and for its personalized management.

Dopamine deficiency contributes to early visual dysfunction in a rodent model of type 1 diabetes

Dopamine (DA) functions as an essential neuromodulator in the brain and retina such that disruptions in the dopaminergic system are associated with common neurologic disorders such as Parkinson's disease. Although a reduction in DA content has been observed in diabetes, its effects in the development of diabetes-induced neuropathy remains unknown. Because the retina is rich in DA and has a well known diabetes-induced pathology (diabetic retinopathy or DR), this study was designed to examine the role of retinal DA deficiency in early visual defects in DR. Using rodent models of type 1 diabetes mellitus, we investigated whether diabetes caused a reduction in retinal DA content in both rats and mice and determined whether restoring DA levels or activating specific DA receptor pathways could improve visual function (evaluated with optokinetic tracking response) of diabetic mice, potentially via improvement of retinal function (assessed with electroretinography). We found that diabetes significantly reduced DA levels by 4 weeks in rats and by 5 weeks in mice, coincident with the initial detection of visual deficits. Treatment with l-DOPA, a DA precursor, improved overall retinal and visual functions in diabetic mice and acute treatment with DA D1 or D4 receptor agonists improved spatial frequency threshold or contrast sensitivity, respectively. Together, our results indicate that retinal DA deficiency is an underlying mechanism for early, diabetes-induced visual dysfunction and suggest that therapies targeting the retinal dopaminergic system may be beneficial in early-stage DR.

Association Analysis of Polymorphisms in Genes Related to Oxidative Stress in South Indian Type 2 Diabetic Patients with Retinopathy

BACKGROUND

Diabetic Retinopathy (DR) is one of the most common microvascular complications of type 2 diabetes mellitus (T2DM) and is polygenic with a multitude of genes contributing to disease susceptibility. The present study aimed at exploring the association between DR and seven polymorphisms in oxidative stress-related genes, i.e. ACE, eNOS, p22phox subunit of NAD(P)H oxidase, PARP-1 and XRCC1 in South Indian T2DM subjects.

MATERIALS AND METHODS

The study included 149 T2DM subjects with DR (diagnosed through funduscopic examination) and 162 T2DM patients with no evidence of DR. The selected polymorphisms were genotyped by polymerase chain reaction (PCR) and Taqman allele discrimination assay.

RESULTS

There was no significant difference in the genotype and allele distribution of ACE ins/del, eNOS-786T>C, 894G>T, 4a4b and p22phox 242C>T polymorphisms between T2DM groups with and without DR. Contrastingly, there appeared to be a significant association of PARP-1 Val762Ala and XRCC1 Arg399Gln polymorphisms with DR, wherein 762Ala allele seemed to confer significant protection against DR (p = 0.01; OR = 0.51 [0.3-0.86]), while the presence of 399Gln allele was associated with an enhanced risk for DR (p = 0.02; OR = 1.52 [1.07-2.15]). Multiple logistic regression analysis revealed a significant and independent association of Val762Ala and Arg399Gln polymorphisms and other putative risk factors with DR in T2DM individuals.

CONCLUSIONS

The polymorphisms in the DNA repair genes PARP-1 and XRCC1 tended to associate significantly with DR. While Val762Ala polymorphism was associated with reduced susceptibility to DR, the Arg399Gln polymorphism contributed an elevated to risk for DR in South-Indian T2DM individuals.

Gender differences in the incidence and progression of diabetic retinopathy among Japanese patients with type 2 diabetes mellitus: a clinic-based retrospective longitudinal study

A clinic-based retrospective longitudinal study conducted for 5.8 ± 2.5 years, including 383 (M/F 245/138) Japanese patients with type 2 diabetes mellitus showed that females exhibit a significantly higher prevalence of proliferative diabetic retinopathy (DR) at baseline and that female gender is an independent risk factor for the development of DR.

The impact of metabolic parameters on clinical response to VEGF inhibitors for diabetic macular edema

AIMS

Evaluate the role of systemic factors on the functional and anatomic outcomes of anti-VEGF therapy for diabetic macular edema (DME).

METHODS

A retrospective consecutive case series of 124 patients with DME treated with anti-VEGF therapy was collected. The main outcome measures were change in best corrected visual acuity (BCVA) and change central subfield macular thickness (CST) measured with spectral-domain ocular tomography coherence (SD-OCT); and their correlation with clinical findings.

RESULTS

Patients with serum hemoglobin A1c values (HbA1c) ≤ 7.0% had a statistically significant improvement in BCVA (20/66 to 20/43, p < 0.001), and those patients with HBA1c > 7.0% also had a significant but less robust improvement in BCVA (20/78 to 20/62, p = 0.024). CST improved significantly in both groups, but showed a larger magnitude of improvement in the group with better DM control [-140.7 microns (p < 0.001) and -83.3 microns (p < 0.001)]. Mean HBA1c levels remained relatively stable during the follow-up in both groups, but patients with improved glucose control during the study duration had a significantly lower retinal thickness than patients that had a stable or worsening HbA1c (mean final CST of 324.3 versus 390.0 μm, respectively, p = 0.042). Other systemic parameters were not correlated with changes in OCT thickness or BCVA. There was not a significant difference related to number of intravitreal injection in the HbA1c ≤ 7.0% group compared to HbA1c > 7.0% group, mean of 5.48 and 6.0 intravitreal injections respectively (p = 0.362).

CONCLUSION

This study suggests that glucose regulation can impact the response to anti-VEGF therapy in the management of DME.

Navigated Laser Therapy for Diabetic Macular Oedema

Navigated laser therapy introduces computerised assistance systems to retinal laser photocoagulation treatment. Some of the main benefits the Navilas system offers over conventional laser include high precision and safety and provides additional advantages in terms of standardisation of planning, execution, documentation, quality assurance and better overall treatment comfort for the patient. Navigated laser therapy is being used with good success in the treatment of diabetic macular oedema (DMO), retinal vein occlusions (RVO) and fastpattern navigated panretinal photocoagulation in proliferative diabetic retinopathy (PDR). In centre-involving DMO, a combination of anti-vascular endothelial growth factor (VEGF) and macular laser may provide advantages over anti-VEGF monotherapy. In terms of navigated laser therapy, recent study data from our clinic and other institutions indicate that combined initial anti-VEGF and navigated macular laser therapy allows treatment success to be achieved and maintained with a significantly reduced number of interventions.

Should we start all patients with diabetic retinopathy on fenofibrates?

There remains a need for strategies that are effective in preventing diabetic retinopathy (DR) or slowing down its progression, which is safe, well-tolerated, and more effective, have a lower risk profile, easy to perform, have more predictable results with less morbidity than the current regimens. Physicians caring for diabetic patients not only need to maximize glycemic control, but also closely monitor and treat other systemic conditions. The consistency of clinical data from the fenofibrate studies showed consistent beneficial effects with fenofibrate in slowing the progression of DR. They demonstrated significant benefit on micro-vascular (i.e., retinopathy and nephropathy) outcome, possibly independent of lipid levels. Can we combine the effectiveness of the current standard procedures with the prevention and slowing down of progression of DR that fenofibrates can offer? Knowledge of the primary mode of action of fenofibrate will be useful for both physicians and patients in determining how best to use this drug as an adjunct in the management of DR and ultimately facilitating the translation of clinical trial data to clinical practice.

The role of O-GlcNAc signaling in the pathogenesis of diabetic retinopathy

Diabetic retinopathy is a leading cause of blindness worldwide. Despite laser and surgical treatments, antiangiogenic and other therapies, and strict metabolic control, many patients progress to visual impairment and blindness. New insights are needed into the pathophysiology of diabetic retinopathy in order to develop new methods to improve the detection and treatment of disease and the prevention of blindness. Hyperglycemia and diabetes result in increased flux through the hexosamine biosynthetic pathway, which, in turn, results in increased PTM of Ser/Thr residues of proteins by O-linked β-N-acetylglucosamine (O-GlcNAc). O-GlcNAcylation is involved in regulation of many nuclear and cytoplasmic proteins in a manner similar to protein phosphorylation. Altered O-GlcNAc signaling has been implicated in the pathogenesis of diabetes and may play an important role in the pathogenesis of diabetic retinopathy. The goal of this review is to summarize the biology of the hexosamine biosynthesis pathway and O-GlcNAc signaling, to present the current evidence for the role of O-GlcNAc signaling in diabetes and diabetic retinopathy, and to discuss future directions for research on O-GlcNAc in the pathogenesis of diabetic retinopathy.

Impact of diabetic retinopathy on late cardiac events after percutaneous coronary intervention

BACKGROUND

Diabetic retinopathy has been identified as a predictor of cardiovascular events and heart failure in patients with diabetes mellitus (DM). This study aimed to assess the impact of diabetic retinopathy on the incidence of late cardiac events following percutaneous coronary intervention.

METHODS

We enrolled 88 consecutive DM patients who underwent elective percutaneous coronary intervention and whose ophthalmologic records were available. Patients were divided into 2 groups: those with diabetic retinopathy (DR+ group; n=47), and those without diabetic retinopathy (DR- group; n=41). We examined the incidence of major adverse cardiac events (MACE) including cardiac death, myocardial infarction, and acute heart failure requiring emergency admission over a period of up to 5 years.

RESULTS

Patients in the DR+ group were likely to have a lower estimated glomerular filtration rate. Kaplan-Meier analysis showed that the event-free survival rates for all MACE, myocardial infarction, and heart failure were significantly lower in the DR+ group than in the DR- group (p=0.002, p=0.025, and p=0.022, respectively). Multivariate Cox proportional hazards analysis indicated that the presence of DR was a significant predictor of MACE (hazard ratio: 8.7; 95% CI: 1.1-69.8, p=0.042).

CONCLUSION

The presence of DR might be a useful predictor of late cardiac events following percutaneous coronary intervention.

A Study of VEGF Gene Polymorphism in Egyptian Patients with Diabetic Retinopathy

BACKGROUND

There are subgroups of patients with diabetes mellitus (DM) in whom diabetic retinopathy (DR) does not develop despite poor long-term control of their disease, while others exercising fairly good control, develop retinopathy. So, we aimed to investigate the association of DR with -2578 polymorphism of the vascular endothelial growth factor (VEGF) gene, which has been reported to be associated with increased VEGF production, in Egyptian diabetic patients.

MATERIALS AND METHODS

This is a case control study in which 148 diabetic patients were enrolled. Among them, 44 subjects had proliferative diabetic retinopathy (PDR), 30 had non-proliferative diabetic retinopathy (NPDR), and 74 individuals without retinopathy served as controls. A single nucleotide polymorphism (SNP) of the VEGF gene, a C→A transversion at -2578 (the C/A polymorphism), was investigated by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP).

RESULTS

We found a higher frequency of the polymorphic genotype in both the NPDR (66.7%) and PDR (72.7%) groups compared to the wild C/C genotype (33.3% in NPDR and 27.3% in PDR), but with no statistically significant difference from the control group. Significant association of the progression of DR to the polymorphic genotype was achieved at diabetes duration more than 20 years.

CONCLUSION

Despite of the higher frequency of both the polymorphic genotype and the A allele in cases with DR compared to the control group, there might be no significant association between the VEGF gene polymorphism and DR per se, unless it is longstanding.

Psychophysical Exams as Early Indicators of Diabetic Retinopathy

Retinopathy is a serious and common complication of diabetes that represents the leading cause of blindness, among people of working age, in developed countries. It is estimated that the number of people with diabetic retinopathy (DR) will increase from 126.6 million in 2011 to 191 million by 2030. The visual function that seems to be affected first in the course of DR is probably the contrast sensitivity; in addition, being mainly a macular function, the perception of colour is also compromised. Moreover, the duration of the disease, the levels of glycated haemoglobin (HbA_1c) and the presence of cystoid macular oedema are strongly associated with the impairment of fixation stability in patients with diabetes with clinically significant macular oedema, suggesting the possible diagnostic role of microperimetry. The test of contrast sensitivity and the microperimetry and the chromatic sensitivity tests have proved to be useful, safe, reproducible and inexpensive tools to diagnose the disease early.

Sensitivity of diabetic retinopathy associated vision loss to screening interval in an agent-based/discrete event simulation model

OBJECTIVE

To examine the effect of changes to screening interval on the incidence of vision loss in a simulated cohort of Veterans with diabetic retinopathy (DR). This simulation allows us to examine potential interventions without putting patients at risk.

METHODS

Simulated randomized controlled trial. We develop a hybrid agent-based/discrete event simulation which incorporates a population of simulated Veterans--using abstracted data from a retrospective cohort of real-world diabetic Veterans--with a discrete event simulation (DES) eye clinic at which it seeks treatment for DR. We compare vision loss under varying screening policies, in a simulated population of 5000 Veterans over 50 independent ten-year simulation runs for each group.

RESULTS

Diabetic Retinopathy associated vision loss increased as the screening interval was extended from one to five years (p<0.0001). This increase was concentrated in the third year of the screening interval (p<0.01). There was no increase in vision loss associated with increasing the screening interval from one year to two years (p=0.98).

CONCLUSIONS

Increasing the screening interval for diabetic patients who have not yet developed diabetic retinopathy from 1 to 2 years appears safe, while increasing the interval to 3 years heightens risk for vision loss.

Genetics in diabetic retinopathy: current concepts and new insights

There is emerging evidence which indicates the essential role of genetic factors in the development of diabetic retinopathy (DR). In this regard it should be highlighted that genetic factors account for 25-50% of the risk of developing DR. Therefore, the use of genetic analysis to identify those diabetic patients most prone to developing DR might be useful in designing a more individualized treatment. In this regard, there are three main research strategies: candidate gene studies, linkage studies and Genome-Wide Association Studies (GWAS). In the candidate gene approach, several genes encoding proteins closely related to DR development have been analyzed. The linkage studies analyze shared alleles among family members with DR under the assumption that these predispose to a more aggressive development of DR. Finally, Genome-Wide Association Studies (GWAS) are a new tool involving a massive evaluation of single nucleotide polymorphisms (SNP) in large samples. In this review the available information using these three methodologies is critically analyzed. A genetic approach in order to identify new candidates in the pathogenesis of DR would permit us to design more targeted therapeutic strategies in order to decrease this devastating complication of diabetes. Basic researchers, ophthalmologists, diabetologists and geneticists should work together in order to gain new insights into this issue.

VEGF-binding aptides and the inhibition of choroidal and retinal neovascularization

Age-related macular degeneration and diabetic retinopathy are leading causes of blindness. Vascular endothelial growth factor (VEGF) is known to be the main factor that induces pathological angiogenesis in these diseases. In this study, we investigate the therapeutic potential and safety profiles of high-affinity peptides targeting VEGF which are identified using an 'aptide' technology. We show that two VEGF-binding aptides, APTVEGF1 and APTVEGF2, demonstrate high binding affinity and specificity to VEGF. Furthermore, they suppress VEGF-induced activation of VEGF receptor-2, in vitro angiogenesis, and in vivo pathological choroidal and retinal neovascularization. Despite potent anti-angiogenic effects, both VEGF-binding aptides do not induce any definite toxicity at the level of cellular viability, histological integrity, and gene expression. Our data show the therapeutic potential of VEGF-binding peptides for the treatment of choroidal and retinal neovascularization.

Neurodegeneration in the diabetic eye: new insights and therapeutic perspectives

Diabetic retinopathy (DR), one of the leading causes of preventable blindness, has been considered a microcirculatory disease of the retina. However, there is emerging evidence to suggest that retinal neurodegeneration is an early event in the pathogenesis of DR, which participates in the development of microvascular abnormalities. Therefore, the study of the underlying mechanisms leading to neurodegeneration and the identification of the mediators in the crosstalk between neurodegeneration and microangiopathy will be essential for the development of new therapeutic strategies. In this review, an updated discussion of the mechanisms involved in neurodegeneration, as well as the link between neurodegeneration and microangiopathy, is presented. Finally, the therapeutic implications and new perspectives based on identifying those patients with retinal neurodegeneration are given.

Visual functions and disability in diabetic retinopathy patients

PURPOSE

This study was undertaken to find correlations between visual functions and visual disabilities in patients with diabetic retinopathy.

METHOD

A cross-sectional study was carried out among 38 visually impaired diabetic retinopathy subjects at the Low Vision Clinic of B.P. Koirala Lions Centre for Ophthalmic Studies, Kathmandu. The subjects underwent assessment of distance and near visual acuity, objective and subjective refraction, contrast sensitivity, color vision, and central and peripheral visual fields. The visual disabilities of each subject in their daily lives were evaluated using a standard questionnaire. Multiple regression analysis between visual functions and visual disabilities index was assessed.

RESULT

The majority of subjects (42.1%) were of the age group 60-70 years. Best corrected visual acuity was found to be 0.73±0.2 in the better eye and 0.93±0.27 in the worse eye, which was significantly different at p=0.002. Visual disability scores were significantly higher for legibility of letters (1.2±0.3) and sentences (1.4±0.4), and least for clothing (0.7±0.3). Visual disability index for legibility of letters and sentences was significantly correlated with near visual acuity and peripheral visual field. Contrast sensitivity was also significantly correlated with the visual disability index, and total scores.

CONCLUSION

Impairment of near visual acuity, contrast sensitivity, and peripheral visual field correlated significantly with different types of visual disability. Hence, these clinical tests should be an integral part of the visual assessment of diabetic eyes.

Frequency, severity and risk indicators of retinopathy in patients with diabetes screened by fundus photographs: a study from primary health care

OBJECTIVE

To determine the frequency, severity and risk indicators of diabetic retinopathy (DR) in patients with diabetes attending a primary care diabetes centre.

METHODS

This observational study was conducted at Diabetic Association of Pakistan - a World Health Organization collaborating center in Karachi, from March 2009 to December 2011. Registered patients with diabetes were screened by two field fundus photographs. Retina specialists graded the signs of retinopathy according to diabetic retinopathy disease severity scale.

RESULTS

Of total registered diabetic patients (n=11,158), 10,768 (96.5 %) were screened for DR. Overall DR was found in 2661 (24.7%) patients. DR was found in decreasing order of frequency in patients with type 2 (n= 2555, 23.7%) followed by patients with type 1 diabetes (n=101, 0.93% ) and patients with gestational diabetes mellitus (GDM) (n=5, 0.46%). Among patients with DR, signs of non-sight threatening retinopathy was dominant. Females and patients of working age group predominantly had retinopathy. Type 1 patients >16 years and type 2 patients < 5 years of history of diabetes had sign of retinopathy in increased frequency.

CONCLUSION

Every forth patient with diabetes in this large cohort had signs of diabetic retinopathy. Females and patients in working age group predominantly had retinopathy. Type 2 patients with short while type 1 patients with long history of diabetes most frequently had DR. Dissemination of the present study findings may help in increasing the awareness of this serious complication of diabetes.

Common polymorphism in the cannabinoid type 1 receptor gene (CNR1) is associated with microvascular complications in type 2 diabetes

Endocannabinoids exert their biological effects via interaction with G-protein coupled cannabinoid receptors CB1 and CB2. Polymorphisms in the CNR1 gene (encoding CB1 receptor) were previously found to be associated with dyslipidemia and cardiovascular diseases. We investigated a role of the polymorphism in CNR1 gene in type 2 diabetes and its complications. The study involved 667 T2DM patients and 450 healthy individuals. All subjects were genotyped for G1359A polymorphism by PCR-RFLP procedure. Genotype frequencies did not differ significantly between patients and controls. The statistically significant differences were seen between T2DM patients with diabetic nephropathy (DN) and those without it (OR for risk allele 2.84, 95% CI 2.04-3.94, p<0.0001). There were also differences between patients with diabetic retinopathy (DR) and those without DR (OR for risk allele 1.81, 95% CI 1.30-2.53, p=0.0005). No differences were observed in diabetic neuropathy. The A allele was more frequent in patients with coexisting cardiovascular disease (CVD) compared to patients without CVD (p=0.0044). The novel finding of our study is the association of the G1359A polymorphism with diabetic nephropathy and diabetic retinopathy in patients with T2DM. This polymorphism was also associated with cardiovascular disease in the patient group.

Proteinuric renal disease in type 2 diabetes-is remission of proteinuria associated with improved mortality and morbidity?

AIMS

Patients with type 2 diabetes and macroalbuminuria are at high risk for end stage renal disease (ESRD), cardiovascular disease and death, but remission of proteinuria may improve prognosis. We examine the effectiveness of currently recommended treatments on inducing remission of proteinuria, and on morbidity and mortality.

METHODS

Observational study of 78 patients with type 2 diabetes (46 male) with mean age (SD) of 61.5 (11) years, with a urinary albumin/creatinine ratio (ACR)≥50 mg/mmol. All were treated with agents blocking the renin-angiotensin system. Follow-up was from recognition of ACR ≥ 50 mg/mmol until death or March 2011 (median 6 years). Remission of proteinuria was defined as ≥70 % reduction from peak ACR, sustained for ≥1 year.

RESULTS

Only 22 of 78 patients (28%) achieved remission of proteinuria. Thirty-six (46%) had at least one major event (death, dialysis or cardiovascular). Remission of proteinuria was associated with lower incidence of ESRD/death (9% vs 36%; p=0.02) but cardiovascular events were not reduced (32% vs 30%). A third of patients had no retinopathy when albuminuria was first recognised, suggesting that non-diabetic renal pathologies were prominent. There was a significant interaction between the severity of diabetic retinopathy and remission of proteinuria on the risk of ESRD/death (p=0.0003).

CONCLUSIONS

Remission of proteinuria was achieved in only a third of patients despite efforts to achieve blood pressure targets <130/80 mmHg. Failure to attain remission of proteinuria was associated with increased risk of ESRD or death, a risk compounded by the presence of severe diabetic retinopathy.

Predictors of diabetic retinopathy in patients with type 2 diabetes who have normoalbuminuria

Background:

Microalbuminuria is an independent predictor of retinopathy, so absence of microalbuminuria may tend clinician not to screen for diabetic retinopathy (DR).

Aim:

The aim of our study was to estimate prevalence of DR in patients with type 2 diabetes who have normoalbuminuria, and to study predictors for DR, which can identify these high-risk individuals.

Subjects and Methods:

In a prospective cross-sectional study that included patients with type 2 DM and normoalbuminuria. Diagnosis of DR was made by a trained ophthalmologist based on the presence of clinical features in the fundus of both eyes following the International Clinical DR guidelines. The statistical analyses were performed using Statistical Package for the Social Sciences 15.0 version software (Chicago, IL, USA). The continuous variables expressed as means (SD and Student's t-test or Mann–Whitney test were used, as appropriate, to determine differences in them. Categorical variables were presented as percentage. The Pearson's Chi-square test or Fisher's exact test, as appropriate, was used to determine the differences in them.

Results:

A total of 226 patients with type 2 DM and normoalbuminuria were enrolled in the study that included 110 males (48.6%), and 116 females (51.4%) Mean (SD) duration of diabetes was 8.2 (5.6) years. DR of any grade was present in 49/226 (22%) patients. Of the patients with DR of any grade, 31/49 (63%) had mild non-proliferative diabetic retinopathy (NPDR) 10/49 (22%) had moderate to severe NPDR and 8/49 (15%) had PDR. Duration of diabetes (OR 1.01, 95% CI, 0.86-2.2, P = 0.04), higher systolic blood pressure (OR 2.2, 95% CI, 1.6-4.5, P = 0.01), low hemoglobin (OR 1.4, 95% CI, 0.45-2.9, P = 0.01), and a higher tertile of urinary albumin excretion rate (OR 4.12, 95% CI, 1.92-7.57, P = 0.001) had independently significant association with DR.

Conclusion:

The risk of DR exists in patients with type 2 diabetes even in normoalbuminuric individuals. Close monitoring is particularly needed if patients have longer duration of diabetes, hypertension, anemia, or high normal albuminuria.

Risk factors of retinopathy in type 2 diabetes mellitus at a tertiary care hospital, Bahawalpur Pakistan

Objectives: To find out the risk factors of diabetic retinopathy in type 2 diabetes mellitus.

Methodology: It was a cross-sectional study involving 300 patients of type 2 diabetes. Clinical history, relevant examination including fundoscopy and lab investigations were done. Data was analysed with SPSS 17.0. T-test and chi square/Fischer exact were applied to determine significance.

Results: Mean age of the patients was 49.04 ± 0.69 years with slight female predominance with male to female ratio of 3:4. Average duration of disease was 7.17 ± 0.38 years. Diabetic retinopathy was diagnosed in (74, 23.9%). Mean HbA1c was 8.15% in patients with retinopathy and 8.884% in those who had no retinopathy (p=0.08). However, duration of DM, age of patients, male gender, high total cholesterol, high LDL and microalbuminuria were significantly associated with the development of retinopathy.

Conclusions: Diabetic retinopathy was found in 23.9% of type 2 diabetics. It was associated with duration of disease, age at presentation, male gender, high total cholesterol, high LDL and microalbuminuria. A single high level of HbA1c was not associated with retinopathy.

Classification of diabetic retinopathy and diabetic macular edema

The global incidence and prevalence of diabetes mellitus (DM) have reached epidemic proportions. Estimates indicate that more than 360 million people will be affected by DM by 2030. All of these individuals will be at risk of developing diabetic retinopathy (DR). It is extremely important to categorize, classify and stage the severity of DR in order to establish adequate therapy. With proper management more than 90% of cases of visual loss can be prevented. The purpose of the current paper is to review the classification of DR with a special emphasis on the International Clinical Disease Severity Scale for DR. This new classification is simple to use, easy to remember and based on scientific evidence. It does not require specialized examinations such as optical coherence tomography or fluorescein angiography. It is based on clinical examination and applying the Early Treatment of Diabetic Retinopathy Study 4:2:1 rule.

Enzymatic vitrectomy for diabetic retinopathy and diabetic macular edema

The aim of this paper is to determine the role of enzymatic vitrectomy performed by intravitreal injection of autologous plasmin enzyme (APE) in the management of diabetic retinopathy and diabetic macular edema (DME). Diabetic patients with proliferative diabetic retinopathy or DME and evident posterior hyaloid adherence to the retinal surface were included. All cases were treated with an initial intravitreal injection of APE and reevaluated one month later, measuring changes in best-corrected visual acuity (BCVA), macular thickness and the status of the posterior hyaloid. A second APE injection was performed in cases with no evident posterior vitreous detachment (PVD) after the initial treatment. Sixty-three eyes were included in the present review. A complete PVD appeared in 38% of cases (24 eyes) after one injection of plasmin and the total increased to 51% (32 eyes) after the second injection, separated at least by one month. The central macular thickness improved in all cases (100%) and BCVA in 89%. Finally, in 50% of eyes with proliferative diabetic retinopathy, a high reduction of new vessels regression was observed. Enzymatic vitrectomy could be considered a good therapeutic alternative in diabetic retinopathy and macular edema.

Diabetic macular edema: New promising therapies

The treatment of diabetic macular edema is rapidly evolving. The era of laser therapy is being quickly replaced by an era of pharmacotherapy. Several pharmacotherapies have been recently developed for the treatment of retinal vascular diseases such as diabetic macular edema. Several intravitreal injections or sustained delivery devices have undergone phase 3 testing while others are currently being evaluated. The results of clinical trials have shown the superiority of some of these agents to laser therapy. However, with the availability of several of these newer agents, it may be difficult to individualize treatment options especially those patients respond differently to various therapies. As such, more effort is still needed in order to determine the best treatment regimen for a given patient. In this article, we briefly summarize the major new therapeutic additions for the treatment of diabetic macular edema and allude to some future promising therapies.

Vascular endothelial growth factor trap-eye (Aflibercept) for the management of diabetic macular edema

Diabetic retinopathy (DR) is the most common cause of visual loss among working age individuals. Diabetic macular edema (DME) is an important complication of DR that affects around one third of the patients with DR. Several treatments have been approved for DME ranging from blood pressure and glycemic control to photocoagulation and more recently the use of vascular endothelial growth factor (VEGF) antagonists. The index review discusses aflibercept (EYLEA^®-Regeneron Pharmaceuticals, Inc., Tarrytown, New York, NY, and Bayer Healthcare Pharmaceuticals, Berlin, Germany) in the context of other VEGF antagonists currently available for the treatment of DME. A systematic search of literature was conducted on PubMed, Scopus, and Google Scholar with no limitation on language or year of publication. Pre-clinical studies of aflibercept have shown a higher affinity of this molecule for vascular endothelial growth factor A (VEGF-A) along with a longer duration of action as compared to other VEGF antagonists. Recent clinical trials have shown visual outcome results for aflibercept to be similarly favorable as compared to other available agents with the added benefit of fewer required injections and less frequent monitoring. Aflibercept presents a potential exciting new addition to the armamentarium of current VEGF antagonists available for the treatment of DME and other retinal vascular diseases. However, further studies are indicated to confirm the role, safety, and efficacy of aflibercept for DME.

Diabetic macular edema: Current management 2013

Diabetic retinopathy (DR) is the leading cause of vision loss of working-age adults, and diabetic macular edema (DME) is the most frequent cause of vision loss related to diabetes. The Wisconsin Epidemiologic Study of Diabetic Retinopathy found the 14-year incidence of DME in type 1 diabetics to be 26%. Similarly the Diabetes Control and Complications Trial reported that 27% of type 1 diabetic patients develop DME within 9 years of onset. The most common type of diabetes, type 2, is strongly associated with obesity and a sedentary lifestyle. An even higher incidence of macular edema has been reported in older patients with type 2 diabetes. Within the last 5 years, the use of intravitreal corticosteroids and intravitreal anti-vascular endothelial growth factor (VEGF) agents have come into clinical practice for the management of DME and several recent randomized clinical trials have shown improved effectiveness of ranibizumab compared to focal/grid laser. In this theme issue, we discuss the classification of DR and the treatment options currently available for the treatment of DME including corticosteroids, anti-VEGF agents, combined therapy, enzymatic vitrectomy (vitreolysis), and new therapies.

Prevalence and factors associated with diabetic retinopathy in a Korean adult population: the 2008-2009 Korea National Health and Nutrition Examination Survey

AIM

We examined the prevalence and factors associated with diabetic retinopathy (DR) in a Korean adult population.

METHODS

Fundus examination data from 10,345 people in the fourth Korea National Health and Nutrition Examination Survey from 2008 to 2009 were examined. For each participant, one 45° nonmydriatic digital retinal image, centered on the fovea, was taken per eye. DR was defined as the presence of one or more retinal microaneurysms or retinal blot hemorrhages with or without more severe lesions.

RESULTS

The weighted prevalence of DR was 0.9% (95% CI, 0.7-1.1) in a Korean adult population and 11.0% (95% CI, 8.9-13.6) in Korean adults with diabetes. In a logistic regression analysis, only HbA1c and diabetes duration were independently associated with DR; the other variables examined, including age, gender, exercise, current smoking, heavy alcohol drinking, presence of hypertension, total cholesterol, triglycerides, high-density lipoprotein cholesterol, anti-lipid medication, oral anti-diabetes treatment, and insulin treatment, were not associated with DR.

CONCLUSIONS

According to these national survey data, 1 in 10 people with diabetes has diabetic retinopathy. Glycemic control is the most important factor for preventing retinopathy in patients with diabetes.

Assessment of awareness of diabetic retinopathy and utilization of eye care services among Turkish diabetic patients

AIMS

Raising awareness of diabetic retinopathy (DR) was shown to be a key element for early diagnosis and treatment of this blinding disease. There is very limited data about the knowledge level, attitude, and behavior of diabetic patients regarding DR in Turkey. This study was planned to assess the awareness of DR and the utilization of eye care services among Turkish diabetic patients.

METHODS

Diabetic patients who were under the care of ophthalmologists, endocrinologists, and/or primary care physicians were administered a questionnaire in order to assess their awareness of diabetes and its ocular complications.

RESULTS

A total of 437 patients (51.8% female and 48.2% male) with a mean age of 55.2 ± 11.9 were included in the study. Of the 437 patients, 31.8% had not been educated about diabetes, 88.1% were aware that diabetes can affect the eyes, and 39.8% thought that diabetics with good glycaemic control might suffer from DR. While 86.7% thought that early diagnosis was possible in DR, 77.3% previously had eye examinations, and 41.9% stated that annual eye examinations were necessary for diabetics. An educational level of middle school or higher, duration of DM longer than 5 years, previous DM education, and recruitment from the university (ophthalmology department and endocrinology department) were associated with better awareness of DR. The independent factors associated with visiting an ophthalmologist on a regular basis were DM education, DM duration, and site of recruitment.

CONCLUSION

Although most of the patients know that DM affects the eye, there is a lack of appropriate knowledge and behavior about the management of DR. The importance of better control of DM and regular eye examination in the prevention of DR should be emphasized.

Diabetic retinopathy: current concepts and emerging therapy

More Americans become blind each year from microvascular complications of diabetes than from any other cause. Several studies have indicated that tight glucose control and lifestyle modification can dramatically reduce the incidence and prevalence of diabetic retinopathy. Research over the past several years has yielded a tremendous increase in our knowledge of the pathogenesis of the damage to the retina that occurs in diabetes and has facilitated our ability to intervene and control the damage. New intravitreal medical therapies supported by government- and industry-supported research are gradually replacing standard laser photocoagulation for the treatment of all forms of retinopathy.

Comparison of choroidal thickness in patients with diabetes by spectral-domain optical coherence tomography

Purpose

To evaluate choroidal thickness in diabetes patients using spectral-domain optical coherence tomography.

Methods

We examined 203 eyes of 203 diabetic participants and 48 eyes of 48 healthy controls. The choroidal thickness at the foveal lesion was measured by enhanced-depth imaging optical coherence tomography. The participants were grouped according to diabetic retinopathy grade: no diabetic change, mild-to-moderate or severe non-proliferative, or proliferative diabetic retinopathy. The study parameters included history, age, axial length, intraocular pressure, central retinal thickness, fasting glucose, and blood pressure.

Results

The subfoveal choroidal thickness was thinner in eyes with non-proliferative or proliferative diabetic retinopathy than in normal eyes (p < 0.01). However, there was no difference between eyes with non-proliferative and proliferative diabetic retinopathy or between eyes with no diabetic change and the controls. Eyes exhibiting macular edema showed no significant difference in choroidal thickness compared with eyes having normal macular contours.

Conclusions

The central choroid is thinner when eyes show diabetic changes on the retina. However, the presence of diabetic macular edema or proliferative change is not associated with more pronounced choroidal thinning.

Epigenetics in ocular diseases

Epigenetics pertains to heritable alterations in gene expression that do not involve modification of the underlying genomic DNA sequence. Historically, the study of epigenetic mechanisms has focused on DNA methylation and histone modifications, but the concept of epigenetics has been more recently extended to include microRNAs as well. Epigenetic patterning is modified by environmental exposures and may be a mechanistic link between environmental risk factors and the development of disease. Epigenetic dysregulation has been associated with a variety of human diseases, including cancer, neurological disorders, and autoimmune diseases. In this review, we consider the role of epigenetics in common ocular diseases, with a particular focus on DNA methylation and microRNAs. DNA methylation is a critical regulator of gene expression in the eye and is necessary for the proper development and postmitotic survival of retinal neurons. Aberrant methylation patterns have been associated with age-related macular degeneration, susceptibility to oxidative stress, cataract, pterygium, and retinoblastoma. Changes in histone modifications have also been observed in experimental models of diabetic retinopathy and glaucoma. The expression levels of specific microRNAs have also been found to be altered in the context of ocular inflammation, retinal degeneration, pathological angiogenesis, diabetic retinopathy, and ocular neoplasms. Although the complete spectrum of epigenetic modifications remains to be more fully explored, it is clear that epigenetic dysregulation is an important contributor to common ocular diseases and may be a relevant therapeutic target.

Feasibility of telemedicine in detecting diabetic retinopathy and age-related macular degeneration

Age-related macular degeneration and diabetic retinopathy are important causes of visual impairment and blindness in the world. Because of recent advances and newly available treatment modalities along with the devastating consequences associated with late stages of these diseases, much attention has been paid to the importance of early detection and improving patient access to specialist care. Telemedicine or, more specifically, digital retinal imaging utilizing telemedical technology has been proposed as an important alternative screening and management strategy to help meet this demand. In this paper, we perform a literature review and analysis that evaluates the validity and feasibility of telemedicine in detecting diabetic retinopathy and age-related macular degeneration. Understanding both the progress and barriers to progress that have been demonstrated in these two areas is important for future telemedicine research projects and innovations in telemedicine technology.

Current status in diabetic macular edema treatments

Diabetes is a serious chronic condition, which increase the risk of cardiovascular diseases, kidney failure and nerve damage leading to amputation. Furthermore the ocular complications include diabetic macular edema, is the leading cause of blindness among adults in the industrialized countries. Today, blindness from diabetic macular edema is largely preventable with timely detection and appropriate interventional therapy. The treatment should include an optimized control of glycemia, arterial tension, lipids and renal status. The photocoagulation laser is currently restricted to focal macular edema in some countries, but due the high cost of intravitreal drugs, the use of laser treatment for focal and diffuse diabetic macular edema (DME), can be valid as gold standard in many countries. The intravitreal anti vascular endothelial growth factor drugs (ranibizumab and bevacizumab), are indicated in the treatment of all types of DME, but the correct protocol for administration should be defined for the different Retina Scientific Societies. The corticosteroids for diffuse DME, has a place in pseudophakic patients, but its complications restricted the use of these drugs for some patients. Finally the intravitreal interface plays an important role and its exploration is mandatory in all DME patients.

Sustained delivery of a HIF-1 antagonist for ocular neovascularization

Doxorubicin (DXR) and daunorubicin (DNR) inhibit hypoxia-inducible factor-1 (HIF-1) transcriptional activity by blocking its binding to DNA. Intraocular injections of DXR or DNR suppressed choroidal and retinal neovascularization (NV), but also perturbed retinal function as demonstrated by electroretinograms (ERGs). DXR was conjugated to novel copolymers of branched polyethylene glycol and poly(sebacic acid) (DXR-PSA-PEG3) and formulated into nanoparticles that when placed in aqueous buffer, slowly released small DXR-conjugates. Intraocular injection of DXR-PSA-PEG3 nanoparticles (1 or 10 μg DXR content) reduced HIF-1-responsive gene products, strongly suppressed choroidal and retinal NV, and did not cause retinal toxicity. In transgenic mice that express VEGF in photoreceptors, intraocular injection of DXR-PSA-PEG3 nanoparticles (10 μg DXR content) suppressed NV for at least 35 days. Intraocular injection of DXR-PSA-PEG3 nanoparticles (2.7 mg DXR content) in rabbits resulted in sustained DXR-conjugate release with detectable levels in aqueous humor and vitreous for at least 105 days. This study demonstrates a novel HIF-1-inhibitor-polymer conjugate formulated into controlled-release particles that maximizes efficacy and duration of activity, minimizes toxicity, and provides a promising new chemical entity for treatment of ocular NV.

Effect of α-linolenic acid on streptozotocin-induced diabetic retinopathy indices in vivo

BACKGROUND AND AIMS

Both oxidative stress and inflammation play a significant role in the pathobiology of diabetic retinopathy. Increased consumption of polyunsaturated fatty acids (PUFAs) may prevent or postpone the occurrence of diabetic retinopathy. Hence, the effect of α-linolenic acid (ALA), an essential fatty acid, on oxidative stress, inflammatory indices and production of vascular endothelial growth factor (VEGF) in streptozotocin-induced diabetic retinopathy indices in vivo was studied.

METHODS

Serum and retina concentrations of vascular endothelial growth factor (VEGF), brain-derived neurotrophic factor (BDNF), interleukin-6 (IL-6), plasma and retina concentrations of lipid peroxides and antioxidant enzymes were estimated in streptozotocin (STZ)-induced diabetic animals.

RESULTS

STZ-induced diabetic rats had significantly higher levels of VEGF in the serum and retina and IL-6 in the serum, whereas BDNF was lower in the serum, all of which reverted to near normal in ALA-treated diabetic animals. STZ treatment decreased serum glutathione peroxidase levels, which was restored to normal by both pre- and post-ALA treatment groups.

CONCLUSIONS

STZ-induced changes in serum glutathione peroxidase, BDNF, VEGF and IL-6 that reverted to near control by ALA treatment, especially in ALA + STZ group, lending support to the concept that both oxidative stress and inflammation participate in DR and ALA treatment is of benefit in its prevention.

Association of serum lipids with diabetic retinopathy in type 2 diabetes

A total number of 140 type 2 diabetic patients with diabetic retinopathy (DR) were enrolled in the study from diabetic clinic during May 2011 till June 2012 to determine correlation between severity of DR with serum lipid and other modifiable risk factors in type 2 diabetic patients. Information including age, sex, height, body weight, body mass index (BMI), waist-hip ratio (WHR), and systolic and diastolic blood pressure was collected from each patient. Fasting plasma sugar, low density lipoprotein (LDL), triglyceride level (TG), high density lipoprotein (HDL), glycated hemoglobin (HbA1C), creatinine, and 24 h urinary albumin excretion was done for each patient. Estimated glomerular filtration rate (eGFR) was measured by modification of diet in renal disease (MDRD) equation. Patients were divided in five groups according to retinopathy status based on early treatment DR study (ETDRS) disease severity level. Statistical analysis was performed with Statistical Packages for Social Sciences (SPSS) statistical software (version 17.0 for Windows). The alpha level was set at P = 0.05 for all tests. Statistically significant positive correlation between severity of DR with systolic blood pressure P = 0.005 (r = 0.974), diastolic blood pressure P = 0.001(r = 0.994), LDL P = 0.005 (r = 0.976), TG P = 0.001 (r = 0.990), and 24 h urinary albumin P = 0.004 (r = 0.977) was documented. DR was also strongly positively correlated with smoking P = 0.017 (r = 0.941) and duration of diabetes P = 0.003 (r = 0.981). There was strong inverse correlation of DR with HDL P = 0.001 (r = -0.994) and eGFR P = 0.002 (r = -0.987). Serum lipids were significantly correlated with severity of DR.

Decursin inhibited proliferation and angiogenesis of endothelial cells to suppress diabetic retinopathy via VEGFR2

Diabetes induces pathologic proliferation and angiogenesis in the retina that leads to catastrophic loss of vision. Decursin is a novel therapeutic that targets the vascular endothelial growth factor (VEGF) receptor (VEGFR) with putative anti-proliferative and anti-angiogenic activities. Thereby we utilized human retinal microvascular endothelial cells (HRMEC) and human umbilical vein endothelial cells (HUVEC) under conditions of excess glucose to explore dose-dependent responses of decursin on markers of migration, angiogenesis, and proliferation. Decursin dose-dependently inhibited tube formation, VEGFR-2 expression, along with relative metabolic activity and 5-bromo-2'-deoxy-uridine (BrdU) activity in both cell lines. We then correlated our findings to the streptozotocin-induced rat model of diabetes. Following three months of decursin treatment VEGFR-2 expression was significantly inhibited. Our data would suggest that decursin may be a potent anti-angiogenic and anti-proliferative agent targeting the VEGFR-2 signaling pathway, which significantly inhibits diabetic retinal neovascularization.

Restoration of endogenous substance P is associated with inhibition of apoptosis of retinal cells in diabetic rats

This study was designed to investigate the alterations of substance P (SP) and its correlation with apoptosis of the retinal neurons in diabetic rats. The study was carried out with diabetic rats induced by streptozotocin. Changes of SP and its mRNA were examined using enzyme-linked immunosorbent assay and reverse transcription polymerase chain reaction. The effect of restoration of SP level by capsaicin (20mg/kg, s.c.) on the apoptosis of the retinal cells was studied. The apoptosis was evaluated by change of ratio of the apoptotic cells and caspase-3 activity in the retina. It was found that increase in apoptosis of retinal cells, by 3.5 fold of control, was accompanied by reduction of SP, by 28% in protein and 32% in the mRNA in the retina at 10 weeks of induction of diabetes, compared to the controls. Capsaicin significantly elevated endogenous SP, by 29% in the mRNA and 17% in protein in the retina, with marked inhibition of the apoptosis and the activity of caspase-3 in the diabetic rats. Induction of diabetes leads to the increase of cell apoptosis and the decrease of SP in the retina. The reduction of the endogenous SP and the increase of the cell apoptosis in the retina of the diabetic rats were reversed by pretreatment with capsaicin. Restoration of SP in the retina may be a novel option for prevention of the retinal injury during development of diabetes.

MicroRNA-dependent cross-talk between VEGF and HIF1α in the diabetic retina

Both HIF1α (hypoxia-inducible factor alpha) and VEGF (vascular endothelial growth factor) are implicated in the pathogenesis of diabetic retinopathy (DR). Competitive endogenous RNAs (ceRNAs) are messenger RNA (mRNA) molecules that affect each other expression through competition for their shared microRNAs (miRNA). However, little is known about the role of ceRNAs in DR. We assess whether the expression of HIF1α and VEGF in DR is interdependent through sequestration of common miRNAs. We used bioinformatics to identify potential miRNAs that affect both genes and validated the interdependence of the genes by silencing or overexpression of the genes and assessed the luciferase-HIF1α 3'UTR activity. We found that HIF1α and VEGF are targeted by 12 common miRNAs. Silencing either HIF1α or VEGF increased the availabilities of the shared miRNAs, therefore suppressed the luciferase-HIF1α 3'UTR activity, whereas over-expressing HIF1α or VEGF increased the luciferase activity. HIF1α was co-expressed with VEGF in-vivo and in-vitro in DR models. Silencing HIF1α transcripts resulted in a significant reduction in VEGF protein levels and vice versa. This interdependence was miRNA- and 3'UTR-dependent, as silencing Dicer abolished the interdependence. Over-expression of a common miRNA (miR-106a) significantly reduced the expression of HIF1α and VEGF and prevented high glucose-induced increased permeability. There is a cross-talk between HIF1α and VEGF through interactions with their common miRNAs. miRNA based therapy can affect the expression of both HIF1α and VEGF and may represent a therapeutic potential for the treatment of DR.

Arginase in retinopathy

Ischemic retinopathies, such as diabetic retinopathy (DR), retinopathy of prematurity and retinal vein occlusion are a major cause of blindness in developed nations worldwide. Each of these conditions is associated with early neurovascular dysfunction. However, conventional therapies target clinically significant macula edema or neovascularization, which occur much later. Intra-ocular injections of anti-VEGF show promise in reducing retinal edema, but the effects are usually transient and the need for repeated injections increases the risk of intraocular infection. Laser photocoagulation can control pathological neovascularization, but may impair vision and in some patients the retinopathy continues to progress. Moreover, neither treatment targets early stage disease or promotes repair. This review examines the potential role of the ureahydrolase enzyme arginase as a therapeutic target for the treatment of ischemic retinopathy. Arginase metabolizes l-arginine to form proline, polyamines and glutamate. Excessive arginase activity reduces the l-arginine supply for nitric oxide synthase (NOS), causing it to become uncoupled and produce superoxide and less NO. Superoxide and NO react and form the toxic oxidant peroxynitrite. The catabolic products of polyamine oxidation and glutamate can induce more oxidative stress and DNA damage, both of which can cause cellular injury. Studies indicate that neurovascular injury during retinopathy is associated with increased arginase expression/activity, decreased NO, polyamine oxidation, formation of superoxide and peroxynitrite and dysfunction and injury of both vascular and neural cells. Furthermore, data indicate that the cytosolic isoform arginase I (AI) is involved in hyperglycemia-induced dysfunction and injury of vascular endothelial cells whereas the mitochondrial isoform arginase II (AII) is involved in neurovascular dysfunction and death following hyperoxia exposure. Thus, we postulate that activation of the arginase pathway causes neurovascular injury by uncoupling NOS and inducing polyamine oxidation and glutamate formation, thereby reducing NO and increasing oxidative stress, all of which contribute to the retinopathic process.

Identification of novel drug targets for the treatment of diabetic retinopathy

Vision loss in diabetic retinopathy (DR) is attributable to retinal vascular disorders that result in macular edema and neoangiogenesis. In addition to laser photocoagulation therapy, intraocular injections of antivascular endothelial growth factor drugs have contributed to the treatment of these disease conditions. Nonetheless, the clinical feasibility of intraocular drug administration has raised an increasing demand to develop alternative drugs that can fundamentally ameliorate the retinal vascular dysfunctions in DR. For this purpose, experimental animal models that reproduce human DR would be of clinical benefit. Despite the unavailability of DR models in rats or mice, pharmacological and genetic manipulations without hyperglycemia have successfully recapitulated retinal edema and neoangiogenesis in postnatal mouse retinas, thereby enabling the understanding of the pathophysiology underlying DR. This article highlights the utility of experimental mouse models of retinal vascular abnormalities and discusses cellular and molecular mechanisms responsible for the onset and progression of DR. These approaches will lead to the identification of novel drug targets for the restoration of vascular integrity and regeneration of functional capillaries in DR.

Preventing diabetes blindness: cost effectiveness of a screening programme using digital non-mydriatic fundus photography for diabetic retinopathy in a primary health care setting in South Africa

BACKGROUND

South Africa like many other developing countries is experiencing an epidemiologic transition with a marked increase in the non-communicable disease (NCD) burden. Diabetic retinopathy is the most common cause of incidental blindness in adults. A screening programme using a mobile fundal camera in a primary care setting has been shown to be effective in the country. Information on affordability and cost is essential for policymakers to consider its adoption.

METHODS

Economic evaluation is the comparative analysis of competing alternative interventions in terms of costs and consequences. A cost effectiveness analysis was done using actual costs from the primary care screening programme.

RESULTS

A total of 14,541 patients were screened in three primary healthcare facilities in the Western Cape. Photographs were taken by a trained technician with supervision by an ophthalmic nurse. The photographs were then read by a medical officer with ophthalmic experience. A cost effective ratio of $1206 per blindness case averted was obtained. This included costs for screening and treating an individual. The cost just to screen a patient for retinopathy was $22. The costs of screening and treating all incident cases of blindness due to diabetes in South Africa would be 168,000,000 ZAR ($19,310,344) per annum.

CONCLUSION

Non mydriatic digital fundoscopy is a cost effective measure in the screening and diagnosis of diabetic retinopathy in a primary care setting in South Africa. The major savings in the long term are a result of avoiding government disability grant for people who suffer loss of vision.

Diabetic retinopathy and endothelial dysfunction in patients with type 2 diabetes mellitus

BACKGROUND

We investigated the relationship between endothelial dysfunction and diabetic retinopathy (DR) in patients with type 2 diabetes.

METHODS

We used a cross-sectional design to examine 167 patients with type 2 diabetes mellitus. All patients underwent biochemical and ophthalmological examination. We assessed endothelial dysfunction by a flow-mediated vasodilation method of the brachial artery. Changes in vasodilation (flow-mediated vasodilatation, %FMD) were expressed as percent change over baseline values.

RESULTS

The mean±standard deviation of patient age was 54.1±8.6 years. The %FMD was significantly lower in patients with DR than without DR. The prevalence of retinopathy decreased across increasing tertiles of %FMD. After adjusting for patients' age, sex, diabetes duration, use of insulin, use of antihypertensive, antiplatelet, and lipid lowering medications, systolic blood pressure, fasting plasma glucose, 2-hour plasma glucose, glycated hemoglobin, and urinary albumin excretion, participants with a reduced %FMD were more likely to have DR (odds ratio, 11.819; 95% confidence interval, 2.201 to 63.461; P=0.004, comparing the lowest and highest tertiles of %FMD).

CONCLUSION

Endothelial dysfunction was associated with DR, which was most apparent when the endothelial dysfunction was severe. Our study provides insights into the possible mechanism of the influence of endothelial dysfunction on the development of DR.

Upregulation of glutamate-aspartate transporter by glial cell line-derived neurotrophic factor ameliorates cell apoptosis in neural retina in streptozotocin-induced diabetic rats

AIMS

Dysfunction of glutamate uptake, largely mediated by the glutamate-aspartate transporter (GLAST), may lead to retinal cell apoptosis in diabetic retinopathy. The aim of this study is to examine how cell apoptosis and the expression level of GLAST in neural retina of a diabetic rat model are changed and whether the neuroretinal apoptosis could be ameliorated by the administration of glial cell line-derived neurotrophic factor (GDNF).

METHODS

Diabetes was induced by intraperitoneal injection of streptozotocin (STZ) in Sprague-Dawley rats. GLAST protein expression levels were determined by Western blotting, whereas apoptosis of retinal neurons was evaluated by TUNEL staining. To assess the role of GDNF in ameliorating the STZ-induced retinal changes, GDNF/GDNF with siRNA directed against GLAST was injected into the vitreous after STZ injection.

RESULTS

In rat retinas 4 weeks after the onset of STZ-induced diabetes, TUNEL-positive cells were significantly increased, whereas GLAST levels were significantly reduced. Intraocular administration of GDNF at the early stage of diabetes remarkably increased the GLAST levels and decreased TUNEL-positive signals in the retinas. These effects of GDNF were largely abolished by coadministration of GLAST siRNA.

CONCLUSIONS

GDNF, administrated at the early stage of diabetes, could rescue retinal cells from neurodegeneration by upregulating the expression of GLAST.

Association study of sorbitol dehydrogenase -888G>C polymorphism with type 2 diabetic retinopathy in Caucasian-Brazilians

Diabetic retinopathy (DR) is a common chronic complication of diabetes and remains the leading cause of blindness in working-aged people. Hyperglycemia increases glucose flux through the polyol pathway, in which aldose reductase converts glucose into intracellular sorbitol, which is subsequently converted to fructose by sorbitol dehydrogenase (SDH). The accelerated polyol pathway triggers a cascade of events leading to retinal vascular endothelial dysfunction and the eventual development of DR. Polymorphisms in the gene encoding aldose reductase have been consistently associated with DR. However, only two studies have analyzed the relationship between polymorphisms in the gene encoding SDH (SORD) and DR. In this case-control study, we investigated whether the -888G > C polymorphism (rs3759890) in the SORD gene is associated with the presence or severity of DR in 446 Caucasian-Brazilians with type 2 diabetes (241 subjects with and 205 subjects without DR). The -888G > C polymorphism was also examined in 105 healthy Caucasian blood donors, and the genotyping of this polymorphism was carried out by real-time PCR. The genotype and allele frequencies of the -888G > C polymorphism in patients with type 2 diabetes were similar to those of blood donors (G allele frequency = 0.16 in both groups of subjects). Similarly, the genotype and allele frequencies in patients with DR or the proliferative form of DR were similar to those of patients without this complication (P > 0.05 for all comparisons). Thus, our findings suggest that the -888G > C polymorphism in the SORD gene is not involved in the pathogenesis of DR in type 2 diabetes.

Treadmill exercise inhibits apoptotic neuronal cell death with suppressed vascular endothelial growth factor expression in the retinas of the diabetic rats

Diabetic retinopathy is one of the most important microvascular complications in diabetes, and it is the major cause of visual loss. Physical exercise is known to ameliorate the symptoms of metabolic syndromes such as diabetic mellitus. In the present study, we investigated the effects of treadmill exercise on vascular endothelial growth factor (VEGF) expression and apoptotic cell death in the retinas of streptozotocin (STZ)-induced diabetic rats. The male Sprague-Dawley rats were randomly divided into three groups (n = 10 in each group): control group, STZ-induce diabetes group, STZ-induced diabetes and treadmill exercise group. To induce diabetes in the experimental animals, a single intraperitioneal injection of STZ (50 mg/kg) was given to each animal. The rats in the exercise group were forced to run on a motorized treadmill for 30 min once a day during 1 week starting 6 weeks after STZ injection. In the present results, VEGF expression in the retinas was increased by induction of diabetes. The numbers of caspase-3-positive and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL)-positive cells in the retinas were also enhanced by induction of diabetes. Treadmill exercise significantly decreased VEGF expression and suppressed the number of TUNEL-positive and caspase-3-positive cells in the retinas of diabetic rats. In the present study, we have shown that treadmill exercise might alleviate the progression of diabetic retinopathy through suppressing VEGF expression and apoptotic cell death in the retinas of the diabetic rats.