Blood pressure control and diabetic retinopathy

Transition probabilities of diabetic retinopathy and death in an Asian population with diabetes

PURPOSE

To evaluate the dynamic transitions in diabetic retinopathy (DR) severity over time and associated risk factors in an Asian population with diabetes.

DESIGN

Longitudinal cohort study METHODS: We analyzed data from 9481 adults in the Singapore Integrated Diabetic Retinopathy Screening Program (2010-2015) with linkage to death registry. A multistate Markov model adjusted for age, sex, systolic blood pressure (SBP), diabetes duration, HbA1c, and body mass index (BMI) was applied to estimate annual transition probabilities between four DR states (no, mild, moderate, and severe/proliferative) and death, and the mean sojourn time in each state.

RESULTS

The median assessment interval was 12 months, with most patients having 3 assessments. Annual probabilities for DR progression (no-to-mild, mild-to-moderate and moderate-to-severe/proliferative) were 6.1 %, 7.0 % and 19.3 %, respectively; and for regression (mild-to-no, moderate-to-mild and severe-to-moderate) were 55.4 %, 17.3 % and 4.4 %, respectively. Annual mortality rates from each DR state were 1.2 %, 2.0 %, 18.7 %, and 30.0 %. The sojourn time in each state were 8.2, 0.8, 0.8 and 2.2 years. Higher HbA1c and SBP levels were associated with progression of no-mild and mild-moderate DR, and diabetes duration with no-to-mild and moderate-to-severe/proliferative DR. Lower HbA1c levels were associated with regression from mild-to-no and moderate-to-mild, and higher BMI with mild-to-no DR.

CONCLUSIONS

Our results suggest a prolonged duration (∼8 years) in developing mild DR, with faster transitions (within a year) from mild or moderate states. Moderate/above DR greatly increases the probability of progression and death as compared to mild DR/below. HbA1c was associated with both progression as well as regression.

Mendelian randomization analysis reveals a causal effect of Streptococcus salivarius on diabetic retinopathy through regulating host fasting glucose

Diabetic retinopathy (DR) is one of leading causes of vision loss in adults with increasing prevalence worldwide. Increasing evidence has emphasized the importance of gut microbiome in the aetiology and development of DR. However, the causal relationship between gut microbes and DR remains largely unknown. To investigate the causal associations of DR with gut microbes and DR risk factors, we employed two-sample Mendelian Randomization (MR) analyses to estimate the causal effects of 207 gut microbes on DR outcomes. Inputs for MR included Genome-wide Association Study (GWAS) summary statistics of 207 taxa of gut microbes (the Dutch Microbiome Project) and 21 risk factors for DR. The GWAS summary statistics data of DR was from the FinnGen Research Project. Data analysis was performed in May 2023. We identified eight bacterial taxa that exhibited significant causal associations with DR (FDR < 0.05). Among them, genus Collinsella and species Collinsella aerofaciens were associated with increased risk of DR, while the species Bacteroides faecis, Burkholderiales bacterium_1_1_47, Ruminococcus torques, Streptococcus salivarius, genus Burkholderiales_noname and family Burkholderiales_noname showed protective effects against DR. Notably, we found that the causal effect of species Streptococcus salivarius on DR was mediated through the level of host fasting glucose, a well-established risk factor for DR. Our results reveal that specific gut microbes may be causally linked to DR via mediating host metabolic risk factors, highlighting potential novel therapeutic or preventive targets for DR.

Insights Into Visual Rehabilitation: Pan-Retinal Photocoagulation for Proliferative Diabetic Retinopathy

This review comprehensively explores pan-retinal photocoagulation (PRP) as a pivotal intervention in visually rehabilitating individuals afflicted with proliferative diabetic retinopathy (PDR). The review begins by elucidating the significance of PDR within the spectrum of diabetic retinopathy (DR), emphasizing the progressive nature of the disease and the consequential impact on visual health. A detailed analysis of PRP follows, encompassing its definition, purpose, and historical development, shedding light on the procedural intricacies and mechanisms of action. The postoperative care and follow-up section underscores the necessity of vigilant monitoring for complications, visual recovery, and the importance of regular ophthalmic check-ups. The subsequent discussion delves into patient education and counseling, stressing the need to manage expectations, encourage lifestyle modifications, and highlight the significance of follow-up appointments. The review concludes with insights into future directions, including advancements in laser technology and emerging therapies, offering a glimpse into the evolving landscape of DR management. By addressing ongoing challenges and embracing innovative approaches, this review provides a comprehensive guide for clinicians, researchers, and healthcare practitioners who visually rehabilitate individuals struggling with PDR.

Tractional Retinal Detachment: Prevalence and Causes in Nigerians

Aim

To determine the causes of tractional retinal detachment (TRD) in Nigerians.

Materials and Methods

A prospective, multicentre study evaluating eyes diagnosed to have TRD. History, clinical examination (including visual acuity, intraocular pressure measurement, anterior segment examination and dilated fundoscopy) and systemic evaluation (including previous diagnosis of diabetes, hypertension, sickle-cell disease and others) were performed in TRD eyes out of a cohort of retinal detachment eyes.

Results

The prevalence of TRD of the 237 patients diagnosed with RD within a one-year study period was 25.7% (61 patients). Eighty eyes were diagnosed with TRD. Thirty-eight eyes of nineteen patients (31%) were bilateral, and 42 (69%) were unilateral. There were 38 male patients (62.3%) and 23 female patients (37.7%). The mean age was 52.3 ± 12.7 years (11-69 years). 88.5% of all TRD patients had an associated systemic disease, diabetes being the most common disease in 88.8% of them. Proliferative diabetic retinopathy was the most common cause of TRD (77.5%) and the most common cause of bilateral TRD. Both trauma and proliferative sickle-cell retinopathy occurred in 3.8% of the eyes. 68.8% of TRD eyes were blind at the presentation. However, the causes of TRD did not show any significant association with blindness (P = 0.819).

Conclusion

Proliferative diabetic retinopathy poses a significant threat to vision, being the most common cause of TRD. Early detection and treatment of proliferative retinopathy in diabetes and sickle-cell disease, and trauma prevention will significantly reduce the burden of blindness due to TRD.

Systolic and Diastolic Blood Pressure Are Independent Risk Factors for Diabetic Retinopathy in Patients with Type 2 Diabetes

BACKGROUND AND AIMS

Diabetic retinopathy (DR) is a microvascular complication of diabetes and represents the leading cause of blindness in working-age adults. The aim of this study was to investigate the risk factors for DR in patients with type 2 diabetes (T2DM) with and without diabetic nephropathy (DN).

METHODS

A total of 160 patients with T2DM were included in the study. Photodocumented retinopathy status was determined according to the EURODIAB protocol. Renal function was determined using creatinine-based estimated glomerular filtration rate (eGFR) and albumin-to-creatinine ratio (ACR). Binary univariate and multiple logistic regression analyses were performed to determine the main predictors of DR.

RESULTS

The prevalence of DR in this studied sample was 46.3%. No significant correlation was observed between DR and age, body mass index, serum lipids, and renal function. Binary logistic regression analysis (no DR/DR) showed that longer diabetes duration (p = 0.008), poor glycemic control (HbA1c) (p = 0.008), higher systolic blood pressure (p = 0.001), and diastolic blood pressure (p = 0.003) were the main predictors of DR in patients with T2DM. However, the influence of systolic blood pressure (AOR = 1.06, p = 0.004) and diastolic blood pressure (AOR = 1.12, p = 0.007) on DR development remained significant even after adjustment for diabetes duration and HbA1c.

CONCLUSIONS

Our results suggest that systolic and diastolic blood pressure are independent risk factors for DR in patients with T2DM.

Elucidating glial responses to products of diabetes-associated systemic dyshomeostasis

Diabetic retinopathy (DR) is a leading cause of blindness in working age adults. DR has non-proliferative stages, characterized in part by retinal neuroinflammation and ischemia, and proliferative stages, characterized by retinal angiogenesis. Several systemic factors, including poor glycemic control, hypertension, and hyperlipidemia, increase the risk of DR progression to vision-threatening stages. Identification of cellular or molecular targets in early DR events could allow more prompt interventions pre-empting DR progression to vision-threatening stages. Glia mediate homeostasis and repair. They contribute to immune surveillance and defense, cytokine and growth factor production and secretion, ion and neurotransmitter balance, neuroprotection, and, potentially, regeneration. Therefore, it is likely that glia orchestrate events throughout the development and progression of retinopathy. Understanding glial responses to products of diabetes-associated systemic dyshomeostasis may reveal novel insights into the pathophysiology of DR and guide the development of novel therapies for this potentially blinding condition. In this article, first, we review normal glial functions and their putative roles in the development of DR. We then describe glial transcriptome alterations in response to systemic circulating factors that are upregulated in patients with diabetes and diabetes-related comorbidities; namely glucose in hyperglycemia, angiotensin II in hypertension, and the free fatty acid palmitic acid in hyperlipidemia. Finally, we discuss potential benefits and challenges associated with studying glia as targets of DR therapeutic interventions. In vitro stimulation of glia with glucose, angiotensin II and palmitic acid suggests that: 1) astrocytes may be more responsive than other glia to these products of systemic dyshomeostasis; 2) the effects of hyperglycemia on glia are likely to be largely osmotic; 3) fatty acid accumulation may compound DR pathophysiology by promoting predominantly proinflammatory and proangiogenic transcriptional alterations of macro and microglia; and 4) cell-targeted therapies may offer safer and more effective avenues for DR treatment as they may circumvent the complication of pleiotropism in retinal cell responses. Although several molecules previously implicated in DR pathophysiology are validated in this review, some less explored molecules emerge as potential therapeutic targets. Whereas much is known regarding glial cell activation, future studies characterizing the role of glia in DR and how their activation is regulated and sustained (independently or as part of retinal cell networks) may help elucidate mechanisms of DR pathogenesis and identify novel drug targets for this blinding disease.

Blood pressure control for diabetic retinopathy

BACKGROUND

Diabetic retinopathy is a common complication of diabetes and a leading cause of visual impairment and blindness. Research has established the importance of blood glucose control to prevent development and progression of the ocular complications of diabetes. Concurrent blood pressure control has been advocated for this purpose, but individual studies have reported varying conclusions regarding the effects of this intervention.

OBJECTIVES

To summarize the existing evidence regarding the effect of interventions to control blood pressure levels among diabetics on incidence and progression of diabetic retinopathy, preservation of visual acuity, adverse events, quality of life, and costs.

SEARCH METHODS

We searched several electronic databases, including CENTRAL, and trial registries. We last searched the electronic databases on 3 September 2021. We also reviewed the reference lists of review articles and trial reports selected for inclusion.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) in which either type 1 or type 2 diabetic participants, with or without hypertension, were assigned randomly to more intense versus less intense blood pressure control; to blood pressure control versus usual care or no intervention on blood pressure (placebo); or to one class of antihypertensive medication versus another or placebo.

DATA COLLECTION AND ANALYSIS

Pairs of review authors independently reviewed the titles and abstracts of records identified by the electronic and manual searches and the full-text reports of any records identified as potentially relevant. The included trials were independently assessed for risk of bias with respect to outcomes reported in this review.

MAIN RESULTS

We included 29 RCTs conducted in North America, Europe, Australia, Asia, Africa, and the Middle East that had enrolled a total of 4620 type 1 and 22,565 type 2 diabetic participants (sample sizes from 16 to 4477 participants). In all 7 RCTs for normotensive type 1 diabetic participants, 8 of 12 RCTs with normotensive type 2 diabetic participants, and 5 of 10 RCTs with hypertensive type 2 diabetic participants, one group was assigned to one or more antihypertensive agents and the control group to placebo. In the remaining 4 RCTs for normotensive participants with type 2 diabetes and 5 RCTs for hypertensive type 2 diabetic participants, methods of intense blood pressure control were compared to usual care. Eight trials were sponsored entirely and 10 trials partially by pharmaceutical companies; nine studies received support from other sources; and two studies did not report funding source. Study designs, populations, interventions, lengths of follow-up (range less than one year to nine years), and blood pressure targets varied among the included trials. For primary review outcomes after five years of treatment and follow-up, one of the seven trials for type 1 diabetics reported incidence of retinopathy and one trial reported progression of retinopathy; one trial reported a combined outcome of incidence and progression (as defined by study authors). Among normotensive type 2 diabetics, four of 12 trials reported incidence of diabetic retinopathy and two trials reported progression of retinopathy; two trials reported combined incidence and progression. Among hypertensive type 2 diabetics, six of the 10 trials reported incidence of diabetic retinopathy and two trials reported progression of retinopathy; five of the 10 trials reported combined incidence and progression. The evidence supports an overall benefit of more intensive blood pressure intervention for five-year incidence of diabetic retinopathy (11 studies; 4940 participants; risk ratio (RR) 0.82, 95% confidence interval (CI) 0.73 to 0.92; I2 = 15%; moderate certainty evidence) and the combined outcome of incidence and progression (8 studies; 6212 participants; RR 0.78, 95% CI 0.68 to 0.89; I2 = 42%; low certainty evidence). The available evidence did not support a benefit regarding five-year progression of diabetic retinopathy (5 studies; 5144 participants; RR 0.94, 95% CI 0.78 to 1.12; I2 = 57%; moderate certainty evidence), incidence of proliferative diabetic retinopathy, clinically significant macular edema, or vitreous hemorrhage (9 studies; 8237 participants; RR 0.92, 95% CI 0.82 to 1.04; I2 = 31%; low certainty evidence), or loss of 3 or more lines on a visual acuity chart with a logMAR scale (2 studies; 2326 participants; RR 1.15, 95% CI 0.63 to 2.08; I2 = 90%; very low certainty evidence). Hypertensive type 2 diabetic participants realized more benefit from intense blood pressure control for three of the four outcomes concerning incidence and progression of diabetic retinopathy. The adverse event reported most often (13 of 29 trials) was death, yielding an estimated RR 0.87 (95% CI 0.76 to 1.00; 13 studies; 13,979 participants; I2 = 0%; moderate certainty evidence). Hypotension was reported in two trials, with an RR of 2.04 (95% CI 1.63 to 2.55; 2 studies; 3323 participants; I2 = 37%; low certainty evidence), indicating an excess of hypotensive events among participants assigned to more intervention on blood pressure.

AUTHORS' CONCLUSIONS

Hypertension is a well-known risk factor for several chronic conditions for which lowering blood pressure has proven to be beneficial. The available evidence supports a modest beneficial effect of intervention to reduce blood pressure with respect to preventing diabetic retinopathy for up to five years, particularly for hypertensive type 2 diabetics. However, there was a paucity of evidence to support such intervention to slow progression of diabetic retinopathy or to affect other outcomes considered in this review among normotensive diabetics. This weakens any conclusion regarding an overall benefit of intervening on blood pressure in diabetic patients without hypertension for the sole purpose of preventing diabetic retinopathy or avoiding the need for treatment for advanced stages of diabetic retinopathy.

Anti-vascular endothelial growth factor for proliferative diabetic retinopathy

BACKGROUND

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

OBJECTIVES

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

SEARCH METHODS

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

SELECTION CRITERIA

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

DATA COLLECTION AND ANALYSIS

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

MAIN RESULTS

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

AUTHORS' CONCLUSIONS

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

Association of anthropometric parameters as a risk factor for development of diabetic retinopathy in patients with diabetes mellitus

OBJECTIVE

To study the relationship of body fat distribution in patients with diabetes mellitus (DM), and its long-term complications like diabetic retinopathy (DR), in Indian population.

METHODS

This was a prospective, cross-sectional observational study involving 1773 subjects diagnosed with DM and 1778 age and gender-matched individuals. The patients with DM were assessed for the presence and severity of DR. Severe non-proliferative DR and proliferative DR were categorised as sight threatening DR (STDR). Anthropometric parameters, i.e., neck circumference (NC); mid-upper arm circumference (MAC); waist circumference (WC); hip circumference (HC); mid-thigh circumference (MTC) and body mass index (BMI) were measured using standardised technique.

RESULTS

The mean age was 59.33 ± 9.32 for DM group, and 66.03 ± 11.04 for non-DM group. DM group showed significantly greater NC, WC, and MTC and significantly reduced MAC and weight. HC and BMI were comparable between the groups. There was a significant positive correlation of MAC and WC (with any level of DR) and MAC, WC, and weight (for STDR); and a significant negative correlation of HC and MTC (with any level of DR) and NC, HC, MTC, and BMI (for STDR). Multiple logistic regression analysis confirmed that WC was the single most important predictor for any level of DR and STDR.

CONCLUSIONS

Association of body fat distribution with DM and DR appears multifactorial. However, central obesity signified by waist circumference appears to be the significant risk related to the development of DR and STDR in Indian population.

Diabetic retinopathy: long-term follow-up of Ecuadorian patients with type 2 diabetes in primary care

Objectives

The aim of this study is to evaluate the prevalence, associated factors, and time for diabetic retinopathy (DR) development in Ecuadorian patients with type 2 diabetes (DM2) followed for 10 years.

Methods

A retrospective cohort study between 2007 and 2017 included 487 patients with DM2 who had at least one dilated fundus eye examination in Diabetes Center in a primary-health-care level followed up for ten years. Data was collected from clinical records. Sociodemographic and laboratory variables were analysed, determining their association (mean difference and bivariate logistic regression) with DR. Survival time was calculated through life tables and Kaplan-Meier analysis.

Results

The prevalence of DR was 19.95% during the 10-year follow-up period. The median time for developing DR was 28.53 (95% CI: 26.89–27.05), showing that 50% of patients have the risk (HR: 4.57) to develop DR in the third decade of DM disease diagnosis. The significant risk factors for progression of DR were duration of DM2, high glycosylated hemoglobin level > 7% (HbA1c Expβ: 1.709, 95% CI: 1.00–2.89), systemic hypertension (HNT Expβ: 2.348 Expβ: 2.348 95% CI: 1.17–4.70%) 95% CI: 1.17–4.70%), low glomerular filtration rate (Expβ: 1.805, GFR, < 60 ml/min/sc1.73) (95% CI: 1.10–2.94) and albuminuria (Expβ: 2.48 Expβ: 2.48 95% CI: 1.49–4.13).

Conclusions

Half of the patients with DM2 treated in a primary level of care will develop DR in the third decade of the disease. There are risk factors related to development of DR, such as low GFR, high HbA1c, albuminuria and HTN. Low GFR, high HbA1c, albuminuria and high blood pressure are related with the presence of retinopathy in diabetes patients.

BLOOD PRESSURE IS ASSOCIATED WITH DIABETIC RETINOPATHY IN TYPE 1 BUT NOT IN TYPE 2 DIABETES

The aim of this study was to investigate the role of systolic blood pressure (SBP) and diastolic blood pressure (DBP) in the development of diabetic retinopathy (DR) in type 1 and type 2 diabetes and to determine the differences between these two types of diabetes. This cross-sectional study included 84 patients with type 1 diabetes (T1DM) and 107 patients with type 2 diabetes (T2DM). Ophthalmologic retinal examination included indirect slit-lamp fundoscopy, color fundus photography according to EURODIAB (EUROpe and DIABetes) protocol and optical coherence tomography. Blood pressure was measured with a mercury sphygmomanometer after a 10-minute rest period. In T1DM, DR was positively associated with SBP (p = 0.035), HbA1c_median (p < 0.001) and hypertensive retinopathy (p < 0.001), while in T2DM DR was positively related only to HbA1c_median (p = 0.021). Binary logistic regression analysis (no DR/DR) showed that diabetes duration and HbA1c_median were the main predictors of DR in both types of diabetes. In contrast, SBP (OR = 1.05, p = 0.045) and hypertensive retinopathy (OR = 3.75, p < 0.001) were the main predictors/indicators of DR only in T1DM. In conclusion, blood pressure is associated with DR in type 1 but not in type 2 diabetes.

The effect of stiffened diabetic red blood cells on wall shear stress in a reconstructed 3D microaneurysm

Blood flow within the vasculature of the retina has been found to influence the progression of diabetic retinopathy. In this research cell resolved blood flow simulations are used to study the pulsatile flow of whole blood through a segmented retinal microaneurysm. Images were collected using adaptive optics optical coherence tomography of the retina of a patient with diabetic retinopathy, and a sidewall (sacciform) microaneurysm was segmented from the volumetric data. The original microaneurysm neck width was varied to produce two additional aneurysm geometries in order to probe the influence of neck width on the transport of red blood cells and platelets into the aneurysm. Red blood cell membrane stiffness was also increased to resolve the impact of rigid red blood cells, as a result of diabetes, in blood flow. Wall shear stress and wall shear stress gradients were calculated throughout the aneurysm domains, and the quantification of the influence of the red blood cells is presented. Average wall shear stress and wall shear stress gradients increased due to the increase of red blood cell membrane stiffness. Stiffened red blood cells were also found to induce higher local wall shear stress and wall shear stress gradients as they passed through the leading and draining parental vessels. Stiffened red blood cells were found to penetrate the aneurysm sac more than healthy red blood cells, as well as decreasing the margination of platelets to the vessel walls of the parental vessel, which caused a decrease in platelet penetration into the aneurysm sac.

Circulating Biomarkers of Inflammation and Endothelial Activation in Diabetic Retinopathy

Inflammation and endothelial activation play a pivotal role in development and progression of diabetic retinopathy (DR), a vision-threatening complication of diabetes mellitus (DM) and the leading cause of blindness in the working age population. Easily accessible and validated biomarkers for DR early diagnosis and progression are required for use in clinical trials: here, we reviewed the available literature to understand the association of circulating levels of selected markers of inflammation and endothelial activation with the presence of nonproliferative and proliferative DR (NPDR and PDR) and investigate the relationship between their systemic and ocular levels. We additionally provide data synthesis and perform statistical analysis for interpretation of the collected evidence. CRP, IL-1β, IL-6, TNFα, sICAM1, and sVCAM1 circulating levels were increased in subjects with DM compared to healthy individuals. Moreover, TNFα and sVCAM1 showed increasing systemic levels with DR presence and severity; circulating CRP increased with the transition from no DR to NPDR, whereas IL-6 was increased in PDR compared to NDPR stages. The relationship between ocular and systemic concentrations of these proteins remained unclear due to the low number of studies with matched sampling. In conclusion, the available data supports the use of systemic biomarkers of inflammation and endothelial activation to identify DM status and DR severity. These systemic biomarkers are likely reflecting an overall state of inflammation and vascular activation in different tissues of the body, including the eyes. Prospective, longitudinal datasets are required to validate these biomarkers as predictors of early DR presence, of DR progression, or for disease monitoring.

General health of patients with diabetic macular edema-The LIPSIA study

PURPOSE

Cardiovascular risk factors such as hypertension or dyslipidemia can influence the incidence and progression of diabetic retinopathy (DR) and diabetic macular edema (DME). The aim of this study is to describe the comorbidities in patients with DME.

METHODS

Prospective, monocentric observational study. Patients presenting for the treatment of DME received laboratory and clinical examinations including 24-hour blood pressure measurement.

RESULTS

Seventy-five consecutive patients were included in the study. The mean age was 61.0 ± 14.5 years, and 83% had type 2 diabetes. The mean body mass index (BMI) was 32.8 ± 6.0 kg/m2. Overweight (BMI ≥ 25 kg/m2) was present in 92% of all patients. HbA1c values were > 7.0% in 57%. Although 87% of the patients already received antihypertensive therapy, the blood pressure (BP) of 82% was still above the recommended target values of systolic < 140 mmHg and diastolic < 80 mmHg. An insufficient nocturnal fall of the systolic BP (< 10%, non-dipping or reverse dipping) was observed in 62%. In 83% of the patients the glomerular filtration rate was ≤ 90 ml/min/1.73m2. Despite 65% of the cohort already receiving lipid-lowering therapy, LDL cholesterol was above the target value of 1.4 mmol/l in 93%. All patients had at least one cardiovascular risk factor in addition to diabetes (overweight, hypertension, insufficient nocturnal BP fall, dyslipidemia, or renal dysfunction) and 86% had ≥ 3 risk factors.

CONCLUSION

DME patients are characterized by highly prevalent cardiovascular risk factors that are poorly controlled. These comorbidities reduce the prognosis and negatively influence existing DR and DME. The data reveal an important opportunity for improving patient care by interaction of the ophthalmologist with the general practitioner and internal specialists for the detection and treatment of these conditions.

Derivation and Validation of Essential Predictors and Risk Index for Early Detection of Diabetic Retinopathy Using Electronic Health Records

Diabetic retinopathy (DR) is a leading cause for blindness among working-aged adults. The growing prevalence of diabetes urges for cost-effective tools to improve the compliance of eye examinations for early detection of DR. The objective of this research is to identify essential predictors and develop predictive technologies for DR using electronic health records. We conducted a retrospective analysis on a derivation cohort with 3749 DR and 94,127 non-DR diabetic patients. In the analysis, an ensemble predictor selection method was employed to find essential predictors among 26 variables in demographics, duration of diabetes, complications and laboratory results. A predictive model and a risk index were built based on the selected, essential predictors, and then validated using another independent validation cohort with 869 DR and 6448 non-DR diabetic patients. Out of the 26 variables, 10 were identified to be essential for predicting DR. The predictive model achieved a 0.85 AUC on the derivation cohort and a 0.77 AUC on the validation cohort. For the risk index, the AUCs were 0.81 and 0.73 on the derivation and validation cohorts, respectively. The predictive technologies can provide an early warning sign that motivates patients to comply with eye examinations for early screening and potential treatments.

Diabetic Retinopathy Environment-Wide Association Study (EWAS) in NHANES 2005-2008

Several circulating biomarkers are reported to be associated with diabetic retinopathy (DR). However, their relative contributions to DR compared to known risk factors, such as hyperglycaemia, hypertension, and hyperlipidaemia, remain unclear. In this data driven study, we used novel models to evaluate the associations of over 400 laboratory parameters with DR compared to the established risk factors. Methods: we performed an environment-wide association study (EWAS) of laboratory parameters available in National Health and Nutrition Examination Survey (NHANES) 2007–2008 in individuals with diabetes with DR as the outcome (test set). We employed independent variable (feature) selection approaches, including parallelised univariate regression modelling, Principal Component Analysis (PCA), penalised regression, and RandomForest™. These models were replicated in NHANES 2005–2006 (replication set). Our test and replication sets consisted of 1025 and 637 individuals with available DR status and laboratory data respectively. Glycohemoglobin (HbA1c) was the strongest risk factor for DR. Our PCA-based approach produced a model that incorporated 18 principal components (PCs) that had an Area under the Curve (AUC) 0.796 (95% CI 0.761–0.832), while penalised regression identified a 9-feature model with 78.51% accuracy and AUC 0.74 (95% CI 0.72–0.77). RandomForest™ identified a 31-feature model with 78.4% accuracy and AUC 0.71 (95% CI 0.65–0.77). On grouping the selected variables in our RandomForest™, hyperglycaemia alone achieved AUC 0.72 (95% CI 0.68–0.76). The AUC increased to 0.84 (95% CI 0.78–0.9) when the model also included hypertension, hypercholesterolemia, haematocrit, renal, and liver function tests.

Deep learning in estimating prevalence and systemic risk factors for diabetic retinopathy: a multi-ethnic study

In any community, the key to understanding the burden of a specific condition is to conduct an epidemiological study. The deep learning system (DLS) recently showed promising diagnostic performance for diabetic retinopathy (DR). This study aims to use DLS as the grading tool, instead of human assessors, to determine the prevalence and the systemic cardiovascular risk factors for DR on fundus photographs, in patients with diabetes. This is a multi-ethnic (5 races), multi-site (8 datasets from Singapore, USA, Hong Kong, China and Australia), cross-sectional study involving 18,912 patients (n = 93,293 images). We compared these results and the time taken for DR assessment by DLS versus 17 human assessors - 10 retinal specialists/ophthalmologists and 7 professional graders). The estimation of DR prevalence between DLS and human assessors is comparable for any DR, referable DR and vision-threatening DR (VTDR) (Human assessors: 15.9, 6.5% and 4.1%; DLS: 16.1%, 6.4%, 3.7%). Both assessment methods identified similar risk factors (with comparable AUCs), including younger age, longer diabetes duration, increased HbA1c and systolic blood pressure, for any DR, referable DR and VTDR (p > 0.05). The total time taken for DLS to evaluate DR from 93,293 fundus photographs was ~1 month compared to 2 years for human assessors. In conclusion, the prevalence and systemic risk factors for DR in multi-ethnic population could be determined accurately using a DLS, in significantly less time than human assessors. This study highlights the potential use of AI for future epidemiology or clinical trials for DR grading in the global communities.

Enhanced hemodynamic responses to angiotensin II in diabetes are associated with increased expression and activity of AT1 receptors in the afferent arteriole

The prevalence of hypertension is about twofold higher in diabetic than in nondiabetic subjects. Hypertension aggravates the progression of diabetic complications, especially diabetic nephropathy. However, the mechanisms for the development of hypertension in diabetes have not been elucidated. We hypothesized that enhanced constrictive responsiveness of renal afferent arterioles (Af-Art) to angiotensin II (ANG II) mediated by ANG II type 1 (AT1) receptors contributes to the development of hypertension in diabetes. In response to an acute bolus intravenous injection of ANG II, alloxan-induced diabetic mice exhibited a higher mean arterial pressure (MAP) (119.1 ± 3.8 vs. 106.2 ± 3.5 mmHg) and a lower renal blood flow (0.25 ± 0.07 vs. 0.52 ± 0.14 ml/min) compared with nondiabetic mice. In response to chronic ANG II infusion, the MAP measured with telemetry increased by 55.8 ± 6.5 mmHg in diabetic mice, but only by 32.3 ± 3.8 mmHg in nondiabetic mice. The mRNA level of AT1 receptor increased by ~10-fold in isolated Af-Art of diabetic mice compared with nondiabetic mice, whereas ANG II type 2 (AT2) receptor expression did not change. The ANG II dose-response curve of the Af-Art was significantly enhanced in diabetic mice. Moreover, the AT1 receptor antagonist, losartan, blocked the ANG II-induced vasoconstriction in both diabetic mice and nondiabetic mice. In conclusion, we found enhanced expression of the AT1 receptor and exaggerated response to ANG II of the Af-Art in diabetes, which may contribute to the increased prevalence of hypertension in diabetes.

Predictors of Development and Progression of Retinopathy in Patients with Type 2 Diabetes: Importance of Blood Pressure Parameters

Diabetic retinopathy (DR) is a chronic microvascular complication associated a worse prognosis. We aimed to evaluate the predictors of development/progression of DR in a cohort of 544 high-risk patients with type 2 diabetes who had annual ophthalmologic examinations over a median follow-up of 6 years. Ambulatory blood pressure (BP) monitoring and aortic stiffness by carotid-femoral pulse wave velocity were performed. Multivariate Cox survival analysis examined the independent predictors of development or progression of DR. During follow-up, 156 patients either newly-developed or worsened DR. Patients who developed/progressed DR had longer diabetes duration, higher ambulatory and clinic BP levels, higher aortic stiffness, and poorer glycemic control than patients who did not developed/progressed DR. After adjustments for baseline retinopathy prevalence, age and sex, a longer diabetes duration (p < 0.001), higher baseline ambulatory BPs (p = 0.013, for 24-hour diastolic BP), and higher mean cumulative exposure of HbA_1c (p < 0.001), clinic diastolic BP (p < 0.001) and LDL-cholesterol (p = 0.05) during follow-up were the independent predictors of development/progression of DR. BP parameters were only predictors of DR development. In conclusion, a longer diabetes duration, poorer glycemic and lipid control, and higher BPs were the main predictors of development/progression of DR. Mean cumulative clinic diastolic BP was the strongest BP-related predictor.

Optimizing Medical Management in Patients with Sight-Threatening Diabetic Retinopathy

INTRODUCTION

Diabetic retinopathy is a leading cause of blindness in adults of working age. Patients with sight-threatening diabetic retinopathy (STDR) often have poor control of modifiable risk factors, including blood pressure and blood glucose. Patients in our eye department with STDR whose diabetes was managed only by their general practitioner (GP) were referred to a diabetes specialist. We have reviewed these referrals and assessed the control of modifiable risk factors in these patients at the time of referral.

METHODS

A retrospective study was performed which identified 54 patients with STDR who had been referred from our eye department to a diabetes specialist between May 2013 and August 2014. Patient demographics, grades of retinopathy, glycated hemoglobin (HbA1c) levels, blood pressure, and lipid profiles were noted from the initial clinic visit and the first clinic appointment after 12 months. Initial management and any subsequent changes to management were recorded.

RESULTS

Of the 54 patients initially referred to the dedicated diabetic retinopathy clinic, data from 32 patients were available for analysis; 22 patients failed to attend the clinic. The majority of patients who presented to the clinic were found to have inadequate control of modifiable risk factors. At the initial clinic visit, nine of the 32 (28%) patients had a blood pressure that was less than the target of 130/80 mmHg and only two (6%) had a HbA1c level of less than the target of 48 mmol/L for type 2 diabetes and 58 mmol/L for type 1 diabetes, respectively. Changes were made to the management in 24 (75%) of the patients. Blood pressure management was changed in 18 (56%) patients. Overall, changes were made to blood pressure management and lipid and glycemic medication, including insulin.

CONCLUSION

The majority of patients with STDR were receiving suboptimal medical management. Collaboration between GPs, diabetes specialists, and ophthalmologists can lead to optimized medical management. All eye departments should develop protocols specifying when patients with diabetic retinopathy should be referred for to a diabetes specialist for input.

Predictors of Functional and Anatomic Outcomes in Patients with Diabetic Macular Edema Treated with Ranibizumab

OBJECTIVE

To investigate baseline predictors of month 24 best-corrected visual acuity (BCVA) and central foveal thickness (CFT) in patients with diabetic macular edema (DME) treated monthly with ranibizumab or sham.

DESIGN

Post hoc analysis of DME patients in 2 identical phase 3 studies.

PARTICIPANTS

Patients randomized to ranibizumab (n = 502) or sham (n = 257).

METHODS

Multivariate regression on predictors with P < 0.20 in univariate logistic regression using backward selection to retain predictors with P < 0.05.

MAIN OUTCOME MEASURES

Patient characteristics correlating with month 24 BCVA in Early Treatment Diabetic Retinopathy Study letter score ≥70 (20/40) or ≤50 (20/100), gain or loss from baseline BCVA of ≥15, or CFT ≤250 μm.

RESULTS

Baseline predictors of BCVA ≥20/40 in ranibizumab-treated patients were good BCVA, submacular fluid, no cardiovascular disease, no scatter photocoagulation, and male gender, whereas in sham-treated patients, they were mild increase in CFT, presence of hard exudates in center subfield, and absence of renal disease. Predictors of improvement in BCVA letter score ≥15 in ranibizumab-treated patients were poor BCVA, submacular fluid, young age, and short diabetes duration, and those in sham-treated patients were poor BCVA, young age, and mild increase in CFT. Predictors of resolution of edema (CFT ≤250 μm) in ranibizumab-treated patients were mild foveal thickening and prominent subfoveal fluid, and those in sham-treated patients were poor BCVA, mild foveal thickening, and statin usage. Month 24 BCVA ≤20/100 was predicted by poor baseline BCVA in ranibizumab-treated patients, and by poor baseline BCVA, large intraretinal cystoid spaces, renal disease, and absence of hypercholesterolemia in sham-treated patients. Loss of BCVA ≥15 letters was predicted in sham-treated patients by submacular fluid, intraretinal cystoid spaces, and renal disease.

CONCLUSIONS

Patients with DME and submacular fluid, intraretinal cysts, severe thickening, or renal disease respond poorly when untreated and respond well to ranibizumab treatment. Elimination of submacular fluid, intraretinal cysts, and severe thickening are important goals of DME treatment, and in patients with renal disease, treatment should be very aggressive, with a goal of eliminating all macular fluid.

Blood pressure control for diabetic retinopathy

BACKGROUND

Diabetic retinopathy is a common complication of diabetes and a leading cause of visual impairment and blindness. Research has established the importance of blood glucose control to prevent development and progression of the ocular complications of diabetes. Simultaneous blood pressure control has been advocated for the same purpose, but findings reported from individual studies have supported varying conclusions regarding the ocular benefit of interventions on blood pressure.

OBJECTIVES

The primary aim of this review was to summarize the existing evidence regarding the effect of interventions to control or reduce blood pressure levels among diabetics on incidence and progression of diabetic retinopathy, preservation of visual acuity, adverse events, quality of life, and costs. A secondary aim was to compare classes of anti-hypertensive medications with respect to the same outcomes.

SEARCH METHODS

We searched a number of electronic databases including CENTRAL as well as ongoing trial registries. We last searched the electronic databases on 25 April 2014. We also reviewed reference lists of review articles and trial reports selected for inclusion. In addition, we contacted investigators of trials with potentially pertinent data.

SELECTION CRITERIA

We included in this review randomized controlled trials (RCTs) in which either type 1 or type 2 diabetic participants, with or without hypertension, were assigned randomly to intense versus less intense blood pressure control, to blood pressure control versus usual care or no intervention on blood pressure, or to different classes of anti-hypertensive agents versus placebo.

DATA COLLECTION AND ANALYSIS

Pairs of review authors independently reviewed titles and abstracts from electronic and manual searches and the full text of any document that appeared to be relevant. We assessed included trials independently for risk of bias with respect to outcomes reported in this review. We extracted data regarding trial characteristics, incidence and progression of retinopathy, visual acuity, quality of life, and cost-effectiveness at annual intervals after study entry whenever provided in published reports and other documents available from included trials.

MAIN RESULTS

We included 15 RCTs, conducted primarily in North America and Europe, that had enrolled 4157 type 1 and 9512 type 2 diabetic participants, ranging from 16 to 2130 participants in individual trials. In 10 of the 15 RCTs, one group of participants was assigned to one or more anti-hypertensive agents and the control group received placebo. In three trials, intense blood pressure control was compared to less intense blood pressure control. In the remaining two trials, blood pressure control was compared with usual care. Five of the 15 trials enrolled type 1 diabetics, and 10 trials enrolled type 2 diabetics. Six trials were sponsored entirely by pharmaceutical companies, seven trials received partial support from pharmaceutical companies, and two studies received support from government-sponsored grants and institutional support.Study designs, populations, interventions, and lengths of follow-up (range one to nine years) varied among the included trials. Overall, the quality of the evidence for individual outcomes was low to moderate. For the primary outcomes, incidence and progression of retinopathy, the quality of evidence was downgraded due to inconsistency and imprecision of estimates from individual studies and differing characteristics of participants.For primary outcomes among type 1 diabetics, one of the five trials reported incidence of retinopathy and one trial reported progression of retinopathy after 4 to 5 years of treatment and follow-up; four of the five trials reported a combined outcome of incidence and progression over the same time interval. Among type 2 diabetics, 5 of the 10 trials reported incidence of diabetic retinopathy and 3 trials reported progression of retinopathy; one of the 10 trials reported a combined outcome of incidence and progression during a 4- to 5-year follow-up period. One trial in which type 2 diabetics participated had reported no primary (or secondary) outcome targeted for this review.The evidence from these trials supported a benefit of more intensive blood pressure control intervention with respect to 4- to 5-year incidence of diabetic retinopathy (estimated risk ratio (RR) 0.80; 95% confidence interval (CI) 0.71 to 0.92) and the combined outcome of incidence and progression (estimated RR 0.78; 95% CI 0.63 to 0.97). The available evidence provided less support for a benefit with respect to 4- to 5-year progression of diabetic retinopathy (point estimate was closer to 1 than point estimates for incidence and combined incidence and progression, and the CI overlapped 1; estimated RR 0.88; 95% CI 0.73 to 1.05). The available evidence regarding progression to proliferative diabetic retinopathy or clinically significant macular edema or moderate to severe loss of best-corrected visual acuity did not support a benefit of intervention on blood pressure: estimated RRs and 95% CIs 0.95 (0.83 to 1.09) and 1.06 (0.85 to 1.33), respectively, after 4 to 5 years of follow-up. Findings within subgroups of trial participants (type 1 and type 2 diabetics; participants with normal blood pressure levels at baseline and those with elevated levels) were similar to overall findings.The adverse event reported most often (7 of 15 trials) was death, yielding an estimated RR 0.86 (95% CI 0.64 to 1.14). Hypotension was reported from three trials; the estimated RR was 2.08 (95% CI 1.68 to 2.57). Other adverse ocular events were reported from single trials.

AUTHORS' CONCLUSIONS

Hypertension is a well-known risk factor for several chronic conditions in which lowering blood pressure has proven to be beneficial. The available evidence supports a beneficial effect of intervention to reduce blood pressure with respect to preventing diabetic retinopathy for up to 4 to 5 years. However, the lack of evidence to support such intervention to slow progression of diabetic retinopathy or to prevent other outcomes considered in this review, along with the relatively modest support for the beneficial effect on incidence, weakens the conclusion regarding an overall benefit of intervening on blood pressure solely to prevent diabetic retinopathy.

Anti-vascular endothelial growth factor for proliferative diabetic retinopathy

BACKGROUND

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

OBJECTIVES

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

SEARCH METHODS

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

SELECTION CRITERIA

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

DATA COLLECTION AND ANALYSIS

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

MAIN RESULTS

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

AUTHORS' CONCLUSIONS

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

Review of the prevalence of diabetic retinopathy in Indigenous Australians

The purpose of this review is to compare the prevalence of diabetic retinopathy (DR) between Indigenous and non-Indigenous Australians with Diabetes Mellitus (DM). Australian DR prevalence data from 6 Indigenous studies (n = 2865) and 5 non-Indigenous studies (n = 9801) conducted between 1985 and 2013 were included for analysis. Estimated prevalence of any DR among Indigenous Australians with DM was 23.4% compared with 28.9% for non-Indigenous Australians (χ(2)  = 26.9, P < 0.001). In studies performed after 1990, a significantly higher rate of diabetic macular edema was found in Indigenous compared with non-Indigenous Australians with DM (7.6% versus 4.9%, χ(2)  = 6.67, P = 0.01). Although there are limitations in comparing these studies, one explanation for the observed data could be a model in which Indigenous Australians are relatively resistant to early stage DR, but with a subset progressing to sight threatening DR due to individual genetic and environmental susceptibility factors coupled with poor glycemic control.

Pathophysiology of diabetic retinopathy

Diabetes is now regarded as an epidemic, with the population of patients expected to rise to 380 million by 2025. Tragically, this will lead to approximately 4 million people around the world losing their sight from diabetic retinopathy, the leading cause of blindness in patients aged 20 to 74 years. The risk of development and progression of diabetic retinopathy is closely associated with the type and duration of diabetes, blood glucose, blood pressure, and possibly lipids. Although landmark cross-sectional studies have confirmed the strong relationship between chronic hyperglycaemia and the development and progression of diabetic retinopathy, the underlying mechanism of how hyperglycaemia causes retinal microvascular damage remains unclear. Continued research worldwide has focussed on understanding the pathogenic mechanisms with the ultimate goal to prevent DR. The aim of this paper is to introduce the multiple interconnecting biochemical pathways that have been proposed and tested as key contributors in the development of DR, namely, increased polyol pathway, activation of protein kinase C (PKC), increased expression of growth factors such as vascular endothelial growth factor (VEGF) and insulin-like growth factor-1 (IGF-1), haemodynamic changes, accelerated formation of advanced glycation endproducts (AGEs), oxidative stress, activation of the renin-angiotensin-aldosterone system (RAAS), and subclinical inflammation and capillary occlusion. New pharmacological therapies based on some of these underlying pathogenic mechanisms are also discussed.

Prevalence and risk factors of diabetic retinopathy in subjects with suboptimal glycemic, blood pressure and lipid control. Sankara Nethralaya Diabetic Retinopathy Epidemiology and Molecular Genetic Study (SN-DREAMS, Report 33)

PURPOSE

To assess the rate of achieving optimal metabolic control among subjects with type 2 diabetes, to elucidate the influence of suboptimal control on diabetic retinopathy (DR) and to analyze the risk factors associated with DR in the subjects with suboptimal control.

MATERIAL AND METHODS

A population-based, cross-sectional study was conducted in south India. The study population consisted of 1414 subjects with type 2 diabetes. Optimal control of glycosylated hemoglobin (HbA1c), blood pressure (BP) and lipids was defined as: optimal HbA1c <7%, suboptimal HbA1c ≥ 7%; optimal BP ≤ 130/80 mm Hg, suboptimal BP >130/80 mm Hg; optimal low-density lipoprotein (LDL-C) <100 mg/dl, suboptimal LDL ≥ 100 mg/dl.

RESULTS

Of the subjects, 13.6% achieved combined optimal target levels for all metabolic parameters. When compared to subjects with optimal control, those with suboptimal control of HbA1c (trend P < 0.0001) and systolic blood pressure (SBP, trend P = 0.007) were more likely to have DR. Subjects having a combination of suboptimal glycemic and BP control (P < 0.0001 for SBP, P = 0.004 for diastolic blood pressure (DBP)), and suboptimal glycemic, BP and LDL control (P < 0.0001 for SBP, P = 0.017 for DBP), were more likely to have DR when compared to the subjects having optimal control of respective combinations. The factors associated with DR in the subjects with suboptimal control were younger age (P = 0.014 for BP, P = 0.016 for HbA1c), male gender (P = 0.035 for BP, P = 0.027 for HbA1c, P = 0.043 for LDL), presence of anemia (P = 0.021 for BP, P = 0.036 for HbA1c) and microalbuminuria (P < 0.0001 for both BP and HbA1c).

CONCLUSIONS

We found high prevalence of suboptimal metabolic control among subjects with type 2 diabetes. Suboptimal glycemic and SBP control, and their combination was the most detrimental for the development of DR.

Diabetic retinopathy: pathogenic mechanisms and current treatments

Since diabetes is now a global epidemic, the incidence of retinopathy, a leading cause of blindness in patients aged 20-74 years, is also expected to rise to alarming levels. The risk of development and progression of diabetic retinopathy is closely associated with the type and duration of diabetes, blood glucose, blood pressure and possibly lipids. It is an unmet medical need that can lead to severe and irreversible loss of vision in people of working age worldwide. The aim of this review is to give an overview of the clinical and anatomical changes during the progression of retinopathy, the underlying pathogenic mechanisms that link hyperglycemia with retinal tissue damage, current treatments, and the emerging pharmacological therapies for this sight-threatening complication of diabetes.

Blood pressure control and awareness among patients with diabetes and hypertension attending a tertiary ophthalmic clinic

AIMS

To assess the proportion of patients who had diabetes and hypertension with optimal blood pressure (BP) control and to describe patients' awareness of the importance of BP control.

METHODS

A cross-sectional survey of out-patients with diabetes who attended the Royal Victorian Eye and Ear Hospital (Melbourne, Australia) was conducted between October 2006 and February 2007. Of 245 patients invited, 220 (90%) participated. Optimal BP control was defined as BP < 130/80 mmHg recorded at the latest visit; proportions of patients with awareness of BP control were defined non-exclusively by: (i) ability to recall a previous BP record and rate the appropriateness of that BP level; (ii) ability to recall the recommended optimal BP control level by current diabetes management guidelines; (iii) knowledge that optimal BP control is important to diabetes management; and (iv) knowledge that optimal BP control is important to eye health.

RESULTS

Of the 220 patients, 176 had both diabetes and hypertension. Of these, 49 of 176 (28%) had BP controlled optimally, and 30 of 176 (17%) recalled and rated a previous recorded BP level appropriately. Fewer than one in four (22%) acknowledged the recommended optimum BP level of < 130/80 mmHg, fewer than one in two (48%) rated BP as important to diabetes management, and one in three (35%) rated BP control as important to eye health.

CONCLUSIONS

In this sample of patients with diabetes and hypertension, fewer than one-third achieved the BP level recommended by clinical guidelines, and fewer than half were aware of the importance of BP control.

Assessment of selected adhesion molecule and proinflammatory cytokine levels in the vitreous body of patients with type 2 diabetes--role of the inflammatory-immune process in the pathogenesis of proliferative diabetic retinopathy

BACKGROUND

The aim of the study is to demonstrate the participation of the inflammatory-immune process in the pathogenesis of proliferative diabetic retinopathy (PDR).

METHODS

Twenty four women and 22 men with type 2 diabetes (mean age 63.97 +/- 9.00 years, mean duration of diabetes 12.56 +/- 6.87 years) were enrolled in the study. Serum concentrations of soluble forms of ICAM-1, VCAM-1 as well as IL-6 and TNF-alpha were evaluated in all study subjects. In 19 patients, simultaneous assessment of selected parameter levels in both serum and vitreous samples was performed. Vitrectomy was performed due to intravitreal hemorrhage, accompanied in some patients by traction retinal detachment. The control group consisted of 15 patients having undergone vitrectomy for reasons other than PDR. Tests were performed using the ELISA method.

RESULTS

Serum and intraocular concentrations of sICAM-1, sVCAM-1, IL-6, TNF-alpha were considerably higher in study subjects with PDR than in controls. Simultaneously, a positive correlation was found between intraocular sVCAM-1 (r = 0.590, p = 0.007), TNF-alpha (r = 0.822, p < 0.001) concentrations and HbA(1)c levels. The above-mentioned dependence was not shown for sICAM-1 and IL-6 vitreous concentration. Local vitreous VCAM-1 level increase was also dependent on vitreous TNF-alpha concentration growth (r = 0.470, p = 0.043). No significant correlation was found between serum and vitreous levels of the selected parameters in the group of 19 patients with PDR.

CONCLUSIONS

Increase in sICAM-1 and sVCAM-1 levels, as well as their correlation with high vitreous IL-6 and TNF-alpha concentrations in patients with PDR, seem to confirm the inflammatory-immune nature of this process. In diabetes, inadequate metabolic control remains an important risk factor in the development of PDR.

Biologic risk factors associated with diabetic retinopathy: the Los Angeles Latino Eye Study

OBJECTIVE

To identify biologic risk factors associated with having diabetic retinopathy (DR) in Latinos with type 2 diabetes mellitus (T2DM).

DESIGN

Population-based cross-sectional study.

PARTICIPANTS

Six thousand three hundred fifty-seven Latinos ages > or =40 years from 6 census tracts in Los Angeles, California.

METHODS

An in-home interview was administered to all participants in the Los Angeles Latino Eye Study (LALES). All participants diagnosed with T2DM underwent a complete ophthalmologic examination including stereoscopic fundus photography (7 standard Early Treatment Diabetic Retinopathy Study fields). Photographs were graded in a masked manner using a modified Airlie House grading system to assess presence and severity of DR. Univariate and stepwise logistic regression analyses were used to identify independent risk factors.

MAIN OUTCOME MEASURES

Biologic risk factors associated with any DR and proliferative DR (PDR).

RESULTS

Of the 7789 eligible individuals in LALES, 6357 (82%) had a clinical examination. One thousand two hundred sixty-three participants had definite diabetes and 1187 Latinos had T2DM. Of those with T2DM, 46% (544) had DR. Stepwise logistic regression analyses revealed that compared with females, males had a 50% higher risk of having any DR (OR = 1.50; P = 0.006). Factors independently associated with a greater risk of having any DR were longer duration of known diabetes (per year, OR = 1.08, P<0.0001), higher glycosylated hemoglobin levels (per 1%, OR = 1.22, P<0.0001); higher systolic blood pressure (per 20 mmHg, OR = 1.26, P = 0.002); and insulin treatment (OR = 1.60, P = 0.01). Factors independently associated with PDR included longer duration of known diabetes (per year, OR = 1.06, P<0.0001); being on insulin treatment (OR = 3.2, P<0.0001); and a higher systolic blood pressure (per 20 mmHg, OR = 1.44, P = 0.01). The relationship of these variables to the risk of having DR or PDR is not a constant linear function in all cases and varies depending on the variable.

CONCLUSIONS

Our study showed that the high risk of DR in adult Latinos is independently associated with both nonmodifiable and modifiable risk factors. These findings suggest that controlling hyperglycemia and hypertension in this ethnic group may reduce the high risk of having DR associated with T2DM.

Impaired reduction of nocturnal systolic blood pressure and severity of diabetic retinopathy

The aim of the present study was to evaluate the influence of elevated levels of nocturnal blood pressure (BP) on diabetic retinopathy (DR). A total of 88 diabetic hypertensive patients were divided according to the stage of DR. They underwent 24 h ambulatory BP monitoring and ophthalmological evaluation, and their average level of fasting blood glucose as well as their glycemic control index (percentage of fasting blood glucose higher than 11.2 mmol/L over the previous four years) were calculated. When diabetic patients with retinopathy (n=29) (group 1) were compared with patients without retinopathy (n=59) (group 2), a significant difference was observed in diabetes duration (124 months [range six to 460 months] versus 43 months [range six to 365 months], respectively; P<0.05). In addition, group 1 showed higher levels of nocturnal systolic BP (NSBP) (141 +/- 22 mmHg versus 132+/-18 mmHg; P<0.05). However, no significant differences were found between the two groups (group 1 and group 2) when diurnal pressoric levels were compared (diurnal systolic BP, 153+/-19 mmHg versus 146+/-19 mmHg, P not significant; and diurnal diastolic BP, 91+/-9 mmHg versus 91+/-13 mmHg, P not significant). DR correlated with diabetes duration (r=0.26; P<0.05) and with glycemic control index (r=0.24; P<0.01). Multivariate regression analysis showed NSBP to be an independent predictor of DR (r(2)=0.12; P<0.01). Moreover, patients with severe stages of DR (preproliferative, proliferative or macular edema) showed a lower decrease of NSBP than the other patients (3.9+/-6.0 mmHg versus 9.2+/-6.0 mmHg; P<0.05). The present study suggests that the absence of 24 h normal pressoric rhythm can interfere with the prevalence and severity of DR.

Effects of mechanical stress and high glucose on pericyte proliferation, apoptosis and contractile phenotype

Pericyte loss is an early step of diabetic retinopathy. High glucose induces apoptosis in retinal pericytes, but systemic and capillary hypertension are also believed to be important in the onset and progression of diabetic retinopathy. The haemodynamic insult of retinal capillary hypertension can be mimicked by exposing pericytes to mechanical stretch. We investigated the effect of stretch combined with high glucose on pericyte proliferation/apoptosis and morphology. Bovine retinal pericytes, cultured in either normal or high glucose concentrations in flexible-base plates, were exposed to mechanical stretch for 48/72 h. Cell replication was determined by both cell counting and DNA synthesis, apoptosis by ELISA, cell morphology and actin cytoskeleton distribution by immunofluorescence. Both reduction in cell proliferation and increase in apoptosis were confirmed in high glucose alone. When cells were subjected to stretch, proliferation was reduced and apoptosis increased in both normal and high glucose in comparison with unstretched controls. In both cases, a synergistic effect of hyperglycaemia combined with stretch was shown. Cell morphology showed modifications of cytoskeleton in all experimental conditions; in particular, cells subjected to stretch showed a clear elongation and translocation of actin fibres. In conclusion, our results show that stretch, alone or combined with high glucose, reduces cell proliferation, increases apoptosis and induces morphological changes in pericyte cytoskeleton. Further elucidations of the mechanisms on the basis of reduced proliferation of pericytes subjected to high glucose and stretch could help to clarify the effects of combined hyperglycaemia and hypertension in the pathogenesis of diabetic retinopathy.

Vascular response of the bulbar conjunctiva to diabetes and elevated blood pressure

OBJECTIVE

Retinovascular changes associated with diabetes have been clearly documented; changes in vessels of the conjunctiva are less well described. We examined changes in conjunctival vessel morphologic features in participants with and without diabetes.

DESIGN

Case-control study.

PARTICIPANTS AND CONTROLS

Fifty-three patients with diabetes (17 with type 1 diabetes, 36 with type 2 diabetes) and 60 controls (all aged 20-94 years).

METHODS

Digital red-free conjunctival images were captured and an automated computer algorithm was used to derive indices that describe the morphologic features of vessels of the conjunctiva. Percentage differences in vessel indices were adjusted for age, gender, blood pressure, and smoking status.

MAIN OUTCOME MEASURES

Mean vessel diameter (micrometers) and vessel density (square millimeters of vessel per square centimeter of bulbar conjunctiva).

RESULTS

A strong positive association between the duration of diabetes and overall mean vessel width was observed (P<0.001), resulting from changes in larger vessels (>80 mum in width). Conversely, the duration of diabetes showed a strong inverse association with vessel area (P<0.001) that appeared to be driven by the trend observed in smaller vessels (<40 mum in width). A 25% reduction (95% confidence interval [CI], -35% to -13%; P<0.001) in vessel density in those with type 1 diabetes and a 14% reduction (95% CI, -24% to -3%; P = 0.016) in those with type 2 diabetes, compared with controls, was observed. Mean vessel widths were 11% (95% CI, 4%-17%; P = 0.001) wider in type 1 and 5% (95% CI, 0%-10%; P = 0.073) wider in those with type 2 diabetes compared with controls. The difference in magnitude of effect for type 1 and type 2 diabetes compared with controls was explained by duration of diabetes. Grade of diabetic retinopathy and elevated blood pressure showed similar but less strong associations with vessel indices.

CONCLUSIONS

Loss of capillaries and macrovessel dilation in the conjunctiva associated with diabetes compares with well-known vessel changes in the retina. Associations between morphologic changes in the conjunctiva and elevated blood pressure were similar but less strong; this may show that diabetic angiopathy predominates in those with both diabetes and elevated blood pressure.

Preventing diabetic retinopathy through control of systemic factors

PURPOSE OF REVIEW

Diabetic retinopathy (DR), the leading cause of vision loss in working-age adults, is associated with many systemic factors that contribute to the severity and progression of this disease. Intensive glycemic and blood pressure control has been shown to delay both the onset and progression of diabetic retinopathy.

RECENT FINDINGS

Studies involving angiotensin-converting enzyme inhibitors are currently underway to elucidate the efficacy of these drugs in further reducing the progression of diabetic retinopathy by means other than just hypertensive control. Dyslipidemia is associated with macular exudates and vision loss. Anticoagulation with aspirin is neither contraindicated in diabetics nor associated with prevention or progression of diabetic retinopathy. The effects of smoking on diabetic retinopathy are equivocal. Pregnancy may be associated with the progression of diabetic retinopathy in the absence of long-term effects if serum glucose levels are well monitored and controlled prior to and during pregnancy.

SUMMARY

Genetic research is providing more insight into the pathogenesis and mechanisms of diabetic retinopathy, allowing possible identification of those at higher risk for developing diabetic retinopathy.

Pathogenesis of diabetic retinopathy and the renin-angiotensin system

Despite the beneficial effects of good glycaemic control, loss of vision because of diabetic retinopathy (DR) still occurs. Recent studies have suggested that hypertension is a risk factor for the development and progression of DR and that blood pressure reduction can delay the progression of retinopathy. The renin-angiotensin system is activated by chronic hyperglycaemia, and the vitreous fluid level of angiotensin II (AII) is elevated in patients with proliferative diabetic retinopathy and diabetic macular oedema. AII increases vascular permeability and promotes neovascularization. It has been suggested that an autocrine-paracrine relationship may exist between AII and vascular endothelial growth factor in the ocular tissues. Accordingly, angiotensin-converting enzyme inhibitors or AII Type 1 (AT1) receptor blockers may be useful therapeutic agents for preventing the progression of DR.