Ocular and systemic causes of retinopathy in patients without diabetes mellitus

Role of pattern electroretinogram in assessment of retinal dysfunction in hypertensive patients

BACKGROUND

Hypertension is a major health problem in both developing and developed countries. Hypertension causes retinal structural and functional impairment within the ganglion cell layer. Pattern electroretinogram (PERG) offers an objective simple tool for assessment of retinal ganglion cell function.Aim of the work: To assess retinal dysfunction in hypertensive patients with or without signs of retinopathy using PERG.

MATERIALS AND METHODS

This is a case control study, including ninety-eight eyes. Twenty-eight eyes of healthy subjects served as a control group (group I) and seventy eyes of patients with systemic hypertension, who were further subdivided into group II including 39 eyes of hypertensive patients with normal fundus and group III including 31 eyes of patients with signs of hypertensive retinopathy. All subjects were subjected to ophthalmological examination and electrophysiological assessment using PERG.

RESULTS

PERG implicit times were significantly prolonged and amplitudes were significantly reduced in patients with established hypertensive retinopathy. PERG abnormalities were detected in 96.8% of hypertensive retinopathy patients and 79.5% of hypertensive patients with normal fundus.

CONCLUSIONS

PERG can objectively assess retinal dysfunction in hypertensive patients and may be considered a promising tool for early detection of hypertensive retinopathy.

Advances in Revascularization for Peripheral Artery Disease: Revascularization in PAD

Effective revascularization of the patient with peripheral artery disease is about more than the procedure. The approach to the patient with symptom-limiting intermittent claudication or limb-threatening ischemia begins with understanding the population at risk and variation in clinical presentation. The urgency of revascularization varies significantly by presentation; from patients with intermittent claudication who should undergo structured exercise rehabilitation before revascularization (if needed) to those with acute limb ischemia, a medical emergency, who require revascularization within hours. Recent years have seen the rapid development of new tools including wires, catheters, drug-eluting technology, specialized balloons, and biomimetic stents. Open surgical bypass remains an important option for those with advanced disease. The strategy and techniques employed vary by clinical presentation, lesion location, and lesion severity. There is limited level 1 evidence to guide practice, but factors that determine technical success and anatomic durability are largely understood and incorporated into decision-making. Following revascularization, medical therapy to reduce adverse limb outcomes and a surveillance plan should be put in place. There are many hurdles to overcome to improve the efficacy of lower extremity revascularization, such as restenosis, calcification, microvascular disease, silent embolization, and tools for perfusion assessment. This review highlights the current state of revascularization in peripheral artery disease with an eye toward technologies at the cusp, which may significantly impact current practice.

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.

Microvascular Disease Increases Amputation in Patients With Peripheral Artery Disease

It is estimated that >2 million patients are living with an amputation in the United States. Peripheral artery disease (PAD) and diabetes mellitus account for the majority of nontraumatic amputations. The standard measurement to diagnose PAD is the ankle-brachial index, which integrates all occlusive disease in the limb to create a summary value of limb artery occlusive disease. Despite its accuracy, ankle-brachial index fails to well predict limb outcomes. There is an emerging body of literature that implicates microvascular disease (MVD; ie, retinopathy, nephropathy, neuropathy) as a systemic phenomenon where diagnosis of MVD in one capillary bed implicates microvascular dysfunction systemically. MVD independently associates with lower limb outcomes, regardless of diabetic or PAD status. The presence of PAD and concomitant MVD phenotype reveal a synergistic, rather than simply additive, effect. The higher risk of amputation in patients with MVD, PAD, and concomitant MVD and PAD should prompt aggressive foot surveillance and diagnosis of both conditions to maintain ambulation and prevent amputation in older patients.

When systemic lupus erythematosus affects vision: a rare presentation of this condition

A 23-year-old woman with fever, oral ulcers, arthalgias and weight loss of 2-week duration suddenly developed blurred vision, with reduced visual acuity, cotton wool exudates and retinal vascular tortuosity. Laboratory testing revealed anaemia, lymphopaenia, positive antinuclear antibody and high anti-dsDNA antibody titre with low complement components. There was no evidence of infection, clinching the diagnosis of lupus retinopathy. Steroid therapy alone was highly effective and was also accompanied by a normalisation of haemoglobin and lymphocyte counts, after which azathioprine was added. Hydroxychloroquine was introduced after resolution of retinal changes. Immunosuppressive therapy was progressively tapered over the course of 12 months and then discontinued, and the patient remains in remission 48 months after the initial presentation. Our patient exemplifies a very rare manifestation of systemic lupus erythematosus. We emphasise the importance of its early detection and complexity of treatment in order to reduce visual morbidity.

Pueraria lobata Extract Protects Hydrogen Peroxide-Induced Human Retinal Pigment Epithelial Cells Death and Membrane Permeability

Background

Pueraria lobata is used in traditional Asian medicine to treat cardiovascular diseases, diarrhea, diabetes mellitus, and diabetic complications such as diabetic retinopathy. Oxidative stress in retinal pigment epithelial cells is implicated in the pathogenesis of retinopathy and age-related macular degeneration (AMD). Here, we evaluated whether the P. lobata extract can prevent cell death and decrease membrane permeability in oxidative stress-induced human retinal pigment epithelial cells.

Methods

The effects of P. lobata extract on hydrogen peroxide- (H₂O₂-) induced oxidative stress were investigated using 2′,7′–dichlorofluorescin diacetate, western blotting, and immunohistochemistry in human retinal pigment epithelial cells. The effects of puerarin, daidzein, and daidzin isolated from P. lobata extract were also studied by determining cell death, reactive oxygen species (ROS) generation, and p38 mitogen-activated protein kinase (MAPK) and c-Jun N-terminal kinase (JNK) phosphorylation.

Results

Our results showed that the P. lobata extract inhibited ROS generation, suppressed the disruption of zonula occludens-1 (ZO-1), and reduced membrane permeability in H₂O₂-induced human retinal pigment epithelial cells. Additionally, the P. lobata extract prevented the inhibition of p38 MAPK and JNK phosphorylation.

Conclusion

Our findings suggest that the P. lobata extract has the potential to prevent AMD development by inhibiting the mechanism underlying oxidative stress-mediated ocular disorders.

The association between bouted and non-bouted physical activity on retinopathy prevalence

OBJECTIVE

We evaluated the specific differential association between non-bouted, lifestyle physical activities (vs. structured exercise; i.e., bouted physical activity) on retinopathy prevalence among a national sample of the broader U.S. adult population.

METHODS

Data from the 2005-2006 National Health and Nutrition Examination Survey (NHANES) was used to identify 1501 adults, between 40 and 85years. Bouted and non-bouted physical activities were assessed using objective accelerometer monitoring. A 10-minute bout was defined as 10+ consecutive minutes above the moderate-to-vigorous physical activity (MVPA) cut-point, with the allowance of 1-2-minute interruption intervals. Non-bout MVPA was determined by the number of MVPA minutes not accrued in a bout. Participants were screened for non-proliferative retinopathy using Early Treatment Diabetic Retinopathy Study grading criteria, as well as objective retinal imaging assessments using the Canon Non-Mydriatic Retinal Camera CR6-45NM. Individuals were excluded if they had been diagnosed with coronary artery disease, congestive heart failure, heart attack or stroke.

RESULTS

Participants with worse retinopathy engaged in less bouted and non-bouted physical activity, had a higher BMI and were more likely to have diabetes and hypertension. For every 1min/day increase in non-bouted MVPA, participants had a 7% reduced odds of moderate-to-severe retinopathy compared to no retinopathy (OR=0.93; 95% CI: 0.87-0.99; P=0.04); results were similar in an unadjusted model (OR=0.93; 95% CI: 0.89-0.97; P=0.007). Bouted MVPA was not associated with retinopathy prevalence in the multivariate model.

CONCLUSION

In this nationally representative sample of adults, those who engaged in non-bouted physical activity had reduced odds of a diagnosis of moderate-to-severe retinopathy.

Obesity, metabolic syndrome and diabetic retinopathy: Beyond hyperglycemia

Diabetic retinopathy (DR) is the most feared ocular manifestation of diabetes. DR is characterized by progressive retinal damage that may eventually result in blindness. Clinically, this blindness is caused by progressive damage to the retinal microvasculature, which leads to ischemia, retinal swelling, and neovascularization. Retinopathy is associated with both type 1 and type 2 diabetes, with DR being the leading cause of new onset blindness in United States adults. Despite this strong association with diabetes, it must be noted that the development of retinopathy lesions is multifactorial and may occur in individuals without an established history of diabetes. Metabolic syndrome is a multifactorial condition of central obesity, hypertriglyceridemia, dyslipidemia, hypertension, fasting hyperglycemia, and insulin resistance. Although several studies examined the individual components observed in the metabolic syndrome in relation to the development of DR, there is conflicting data as to the association of the metabolic syndrome with the development of retinopathy lesions in non-diabetic subjects. This review will summarize the current literature on the evidence of the metabolic syndrome on retinopathy in subjects with and without an established history of diabetes. This review will also discuss some of the mechanisms through which metabolic syndrome can contribute to the development of retinopathy.

Retinal vascular abnormalities in neovascular age-related macular degeneration

PURPOSE

To determine the prevalence of retinal vascular abnormalities (RVA) in neovascular age-related macular degeneration (AMD).

METHODS

A post hoc subanalysis of images acquired during a Phase III randomized controlled trial was undertaken, selecting images from participants with untreated, neovascular AMD in at least one eye. Protocol mandated fundus photographs and fluorescein angiograms were acquired at baseline and Year 2, from 107 sham-treated study eyes with neovascular AMD and 107 untreated fellow eyes. Images were reanalyzed by an independent reading center for the presence of RVA, defined as at least one of the following: microaneurysms, vessel staining or leakage, dilated or tortuous vessels, intraretinal hemorrhage, vessel sheathing or narrowing, capillary nonperfusion, or capillary infarcts.

RESULTS

The baseline prevalence of RVA in the sham-treated study eyes was 14.4% (15 of 104 gradable images) versus 8.3% (5 of 60) in the fellow eyes with dry AMD. The baseline prevalence of individual RVAs in study eyes was: microaneurysms (6.7%), vessel staining or leakage (6.7%), dilated or tortuous vessels (4.8%), intraretinal hemorrhage (4.8%), vessel sheathing or narrowing (2.9%), capillary nonperfusion (0%), and capillary infarcts (0%). Results were similar at 24 months.

CONCLUSION

Compared with several studies that relied solely on fundus photographs, this study included fluorescein angiography and found a higher prevalence of RVAs occurring in eyes with neovascular AMD.

Inflammation, haemostatic disturbance, and obesity: possible link to pathogenesis of diabetic retinopathy in type 2 diabetes

PURPOSE

The pathogenesis of diabetic retinopathy (DR) is insufficiently understood but may possibly involve chronic, low-grade inflammation. The aim of this cross-sectional study was to investigate the relationship between inflammatory and haemostatic markers, other markers of endothelial dysfunction and anthropometric parameters, and their association with DR in patients with type 2 diabetes.

METHODS

According to the DR status patients were divided into three groups: no retinopathy, mild/moderate nonproliferative (NPDR), and severe NPDR/proliferative retinopathy (PDR).

RESULTS

The groups did not differ in the levels of inflammatory and haemostatic markers, other markers of endothelial dysfunction, and anthropometric parameters. After dividing the patients according to the level of obesity (defined by BMI, WC, and WHR) into three groups ANOVA showed the differences in C-reactive protein according to the WC (P = 0.0265) and in fibrinogen according to the WHR (P = 0.0102) as well as in total cholesterol (P = 0.0109) and triglycerides (P = 0.0133) according to the BMI. Logistic regression analyses showed that diabetes duration and prolonged poor glycemic control are the main predictors of retinopathy in patients with type 2 diabetes.

CONCLUSION

Interrelations between obesity, inflammation, haemostatic disturbance, and other risk factors may possibly play an important additional role in endothelial dysfunction involved in the pathogenesis of diabetic retinopathy.

Microvascular retinopathy in subjects without diabetes: the Inter99 Eye Study

PURPOSE

Retinal vascular lesions such as microaneurysms and haemorrhages, while typical of diabetic retinopathy, are also seen in subjects without diabetes where they are associated with elevated cardiovascular mortality. In theory, these lesions could be a consequence of past hyperglycaemia. We examined the prevalence and risk factors for retinopathy, including lens fluorescence, a biomarker of cumulative life-time glycaemia in adults without diabetes.

METHODS

Cross-sectional population-based study of 711 subjects without diabetes (WHO 1999 criteria) aged 30-60 years, including oral glucose tolerance testing, clinical and laboratory examinations, non-invasive ocular lens fluorometry and seven-field fundus photography.

RESULTS

  Retinopathy was present in 8.3% (CI(95) 6.3-10.3%) of subjects. Higher systolic blood pressure (SBP) (p = 0.032), increasing body mass index (BMI) (p = 0.014) and wider waist circumference (p = 0.014) were significantly associated with retinopathy after adjusting for age and sex. Retinopathy was not significantly related to long-term, short-term or current glycaemia (lens fluorescence, HbA(1c) , fasting plasma glucose). In the multivariate analysis, the odds ratio (OR) for retinopathy in subjects with SBP ≥160 mmHg compared to subjects with SBP <130 mmHg was 2.68 (CI(95) 1.07-6.70, p = 0.036) and in subjects with BMI ≥30 compared to subjects with BMI < 25 the OR for retinopathy was 2.14 (CI(95) 1.01-4.57, p = 0.049) when adjusting for both variables, age, sex, the presence of impaired glucose tolerance and impaired fasting glucose.

CONCLUSION

 Retinopathy in subjects without diabetes was associated with hypertension and obesity. The study found no evidence that microvascular retinopathy in non-diabetic subjects was a consequence of past hyperglycaemia.

Alternative pathways in the development of diabetic retinopathy: the renin-angiotensin and kallikrein-kinin systems

Diabetic retinopathy is a common complication of both type 1 and type 2 diabetes and is the leading cause of blindness in people of working age. Current treatment strategies are mostly limited to laser photocoagulation, which restricts proliferative retinopathic changes but also causes irreversible damage to the retina. This review examines two important pathways involved in regulating vascular function and their role in the development of diabetic retinopathy. One, the renin-angiotensin system, is well known and has established angiogenic effects on the retina that increase in diabetic retinopathy. The other, the kallikrein-kinin system, has recently been found to be important in the development of diabetic retinal complications. This review describes the components of the two signalling networks, examines the current animal model studies investigating the role of these pathways in diabetic retinopathy and reviews the clinical studies that have been undertaken examining systemic inhibition of different points in these pathways. These systems are promising targets for therapies aimed at inhibiting the development of diabetic retinopathy and in the future, combination therapies that take advantage of both pathways might result in new treatment options for this debilitating complication of diabetes.

Retinopathy signs in people without diabetes: the multi-ethnic study of atherosclerosis

OBJECTIVE

To describe the prevalence of retinopathy and associations with cardiovascular risk factors in persons without diabetes in 4 racial/ethnic groups (white, black, Hispanic, and Chinese).

DESIGN

Population-based, cross-sectional study.

PARTICIPANTS

We included 6176 subjects aged 45-84 years without diabetes, selected from 6 United States communities.

METHODS

Fundus images were taken using 45° digital camera through dark-adapted pupils and were graded for retinopathy as defined by the Early Treatment Diabetic Retinopathy Study severity scale: microaneurysms, hemorrhages, cotton wool spots, intraretinal microvascular abnormalities, hard exudates, venous beading, and new vessels.

MAIN OUTCOME MEASURES

Retinopathy and the association with cardiovascular risk factors.

RESULTS

Prevalence rates of retinopathy in persons without diabetes were 12.5% overall, varying from 11.9% (white), 13.9% (black), 12.6% (Hispanic), to 17.2% (Chinese). Hypertension was strongly associated with retinopathy (odds ratio [OR], 1.47; 95% confidence interval [CI], 1.23-1.75). After adjusting for age, gender, race, and other parameters, smoking (OR, 1.50; 95% CI, 1.09-2.06) and increased internal carotid intima media thickness (OR, 1.22; 95% CI, 1.05-1.41) were associated with retinopathy. A range of serum inflammatory factors were examined, but none were found to be significant.

CONCLUSIONS

Retinopathy in persons without diabetes is common, varies with race/ethnicity, and associated with cardiovascular risk factors, including hypertension, smoking, and carotid artery intima media thickness.

Radiation retinopathy: a mistaken diagnosis of hypertensive retinopathy

Radiation retinopathy is a vision-threatening complication following therapeutic irradiation of ocular, orbital, facial, nasopharyngeal and cranial structures. It is characterised by a delayed onset, slowly progressive, occlusive retinal microangiopathy that develops several years after initial radiotherapy. We present the case of a 44-year-old man who developed radiation retinopathy, initially diagnosed as a case of hypertensive retinopathy, following irradiation of a nasopharyngeal carcinoma. A careful history along with classical clinical features and fundus fluorescein angiography helped establish the diagnosis.

The clinical assessment of retinal microvascular structure and therapeutic implications

Examination of the retinal microvasculature is widely used to assess diabetic eye disease and as an indicator of target organ damage in hypertension. The diagnostic value of grading of hypertensive retinopathy is dubious; however, many recent studies have demonstrated that hypertensive retinopathy is associated with a range of risk factors for cardiovascular disease and may predict cardiovascular events independently of blood pressure. Developments in digital imaging and computer-assisted analysis have facilitated the quantitative assessment of microvascular changes in cardiovascular disease. These approaches may be useful for assessing cardiovascular risk and targeting therapeutic intervention.

Five-year incidence and progression of vascular retinopathy in persons without diabetes: the Blue Mountains Eye Study

PURPOSE

To assess the 5-year incidence of vascular retinopathy and its associations in an older nondiabetic population.

METHODS

The Blue Mountains Eye Study examined 3654 residents aged 49+ years (82.4% response rate) during 1992-1994, and re-examined 2335 (75.1% of survivors) during 1997-1999. Retinopathy lesions (microaneurysms, haemorrhages, hard or soft exudates) were assessed from 6-field retinal photographs in persons without diabetes. Incident retinopathy was assessed in those at risk. Hypertensive status was defined following the WHO/International Society of Hypertension guidelines.

RESULTS

Of the 2335 re-examined, 195 had retinopathy lesions at baseline and 1725 were at risk of retinopathy after excluding subjects with diabetes (n=261), retinal vein occlusion (n=52) or missing/un-gradable photographs (n=102). The cumulative 5-year incidence was 9.7% (95% confidence intervals (CI) 8.3-11.1%). Age was the only factor significantly associated with incident retinopathy (Pfor trend=0.012). Neither fasting blood glucose (age-sex-adjusted P=0.147) nor hypertension (adjusted Pfor trend=0.43) was associated with incident retinopathy. Of the 195 with retinopathy lesions at baseline, 3.5% developed diabetes, 13.3% progressed, and 72.3% regressed/disappeared over 5 years. Progression was positively associated with elevated blood pressure (BP) (adjusted odds ratio (OR) 1.3, 95% CI 1.1-1.6 per 10 mmHg systolic BP) and inversely associated with fasting glucose level (OR 0.36, CI 0.14-0.92 per mmol/l increase). Aspirin use was weakly associated with regression (OR 2.4, CI 1.0-6.0).

CONCLUSIONS

Over 5 years, retinopathy developed in 10% of older people without diabetes, while 72% of baseline lesions regressed. Age was significantly associated with the development of these lesions.