Types of Exudates in Diabetic Retinopathy

Deep CNN with Hybrid Binary Local Search and Particle Swarm Optimizer for Exudates Classification from Fundus Images

Diabetic retinopathy is a chronic condition that causes vision loss if not detected early. In the early stage, it can be diagnosed with the aid of exudates which are called lesions. However, it is arduous to detect the exudate lesion due to the availability of blood vessels and other distractions. To tackle these issues, we proposed a novel exudates classification from the fundus image known as hybrid convolutional neural network (CNN)-based binary local search optimizer-based particle swarm optimization algorithm. The proposed method from this paper exploits image augmentation to enlarge the fundus image to the required size without losing any features. The features from the resized fundus images are extracted as a feature vector and fed into the feed-forward CNN as the input. Henceforth, it classifies the exudates from the fundus image. Further, the hyperparameters are optimized to reduce the computational complexities by utilization of binary local search optimizer (BLSO) and particle swarm optimization (PSO). The experimental analysis is conducted on the public ROC and real-time ARA400 datasets and compared with the state-of-art works such as support vector machine classifiers, multi-modal/multi-scale, random forest, and CNN for the performance metrics. The classification accuracy is high for the proposed work, and thus, our proposed outperforms all the other approaches.

Review of Machine Learning Applications Using Retinal Fundus Images

Automating screening and diagnosis in the medical field saves time and reduces the chances of misdiagnosis while saving on labor and cost for physicians. With the feasibility and development of deep learning methods, machines are now able to interpret complex features in medical data, which leads to rapid advancements in automation. Such efforts have been made in ophthalmology to analyze retinal images and build frameworks based on analysis for the identification of retinopathy and the assessment of its severity. This paper reviews recent state-of-the-art works utilizing the color fundus image taken from one of the imaging modalities used in ophthalmology. Specifically, the deep learning methods of automated screening and diagnosis for diabetic retinopathy (DR), age-related macular degeneration (AMD), and glaucoma are investigated. In addition, the machine learning techniques applied to the retinal vasculature extraction from the fundus image are covered. The challenges in developing these systems are also discussed.

REvisiting Lipids in REtinal Diseases: A Focused Review on Age-related Macular Degeneration and Diabetic Retinopathy

Dyslipidemia refers to an abnormal amount of lipid in the blood, and the total cholesterol level is defined as the sum of high-density lipoprotein cholesterol, low-density lipoprotein (LDL) cholesterol, and very-LDL cholesterol concentrations. In Korea, the westernization of lifestyle habits in recent years has caused an increase in the incidence of dyslipidemia, which is an important risk factor of cardiovascular disease (CVD). Several studies have been conducted on how dyslipidemia affects not only CVD, but also chorioretinal diseases such as age-related macular degeneration (AMD) and diabetic retinopathy. Recently, a pathological model of AMD was proposed under the assumption that AMD proceeds through a mechanism similar to that of atherosclerotic CVD. However, controversy remains regarding the relationship between chorioretinal diseases and lipid levels in the blood, and the effects of lipid-lowering agents. Herein, we summarize the role of lipids in chorioretinal diseases. In addition, the effects of lipid-lowering agents on the prevention and progression of chorioretinal diseases are presented.

The Role of Dyslipidemia Control in the Progression of Diabetic Retinopathy in Patients with Type 2 Diabetes Mellitus

Diabetic retinopathy (DR) is a common microvascular complication of diabetes mellitus (DM) and is considered as the leading cause of visual impairment in working-aged adults worldwide. Dyslipidemia has been associated with DR, but not with progression to the proliferative form of DR, although the exact role in the pathogenesis of DR and diabetic macular edema (DME) remains controversial. As a result, a reasonable question arising is whether control of dyslipidemia may alter the course of DR. Statins do not appear to have an impact on DR progression. On the other hand, fenofibrate has been found to significantly reduce the rate of progression of DR in patients with pre-existing mild DR, although it has no impact on patient's vision nor on the prevention of DR development in patients with type 2 DM without DR. An interesting point that needs further evaluation is why patients without DR or those with severe DR appear to have no benefit from fenofibrate treatment.

High-Resolution Imaging by Adaptive Optics Scanning Laser Ophthalmoscopy Reveals Two Morphologically Distinct Types of Retinal Hard Exudates

Histological studies from autopsy specimens have characterized hard exudates as a composition of lipid-laden macrophages or noncellular materials including lipid and proteinaceous substances (hyaline substances). However, the characteristics of hard exudates in living patients have not been examined due to insufficient resolution of existing equipment. In this study, we used adaptive optics scanning laser ophthalmoscopy (AO-SLO) to examine the characteristics of hard exudates in patients with retinal vascular diseases. High resolution imaging using AO-SLO enables morphological classification of retinal hard exudates into two types, which could not be distinguished either on fundus examination or by spectral domain optical coherence tomography (SD-OCT). One, termed a round type, consisted of an accumulation of spherical particles (average diameter of particles: 26.9 ± 4.4 μm). The other, termed an irregular type, comprised an irregularly shaped hyper-reflective deposition. The retinal thickness in regions with round hard exudates was significantly greater than the thickness in regions with irregular hard exudates (P = 0.01 →0.02). This differentiation of retinal hard exudates in patients by AO-SLO may help in understanding the pathogenesis and clinical prognosis of retinal vascular diseases.

The "Statinth" wonder of the world: a panacea for all illnesses or a bubble about to burst

After the introduction of statins in the market as effective lipid lowering agents, they were shown to have effects other than lipid lowering. These actions were collectively referred to as 'pleiotropic actions of statins.' Pleiotropism of statins formed the basis for evaluating statins for several indications other than lipid lowering. Evidence both in favour and against is available for several of these indications. The current review attempts to critically summarise the available data for each of these indications.

The role of serum lipids in exudative diabetic maculopathy: is there a place for lipid lowering therapy?

Diabetic maculopathy is a common complication of diabetes mellitus, characterised by macular oedema and frequently accompanied by lipid exudation. It is the major cause of loss of vision from diabetic retinopathy. There is some evidence to implicate serum lipids in exudative maculopathy; cross-sectional studies suggest that higher serum lipid levels are found in patients with macular exudates, and prospective studies have shown an increased risk of exudative maculopathy if baseline cholesterol is higher. The treatment for diabetic maculopathy is laser photocoagulation of the pigment epithelium. With the advent of systemic lipid lowering therapy over the last decade, there may be potential for medical therapy also. There is some anecdotal evidence of the effect of lipid lowering agents (particularly statins) in reducing exudate, and a number of studies have shown that lipid lowering therapy may reduce macular exudates, but numbers in these trials are small. A randomised controlled trial is now required to investigate whether the use of systemic lipid lowering therapy is of benefit in patients with exudative maculopathy, even in the absence of dyslipidaemia.

Determinants of retinopathy progression in type 1 diabetes mellitus

PURPOSE

To determine the risk factors for retinopathy progression in type 1 (insulin-dependent) diabetes mellitus in a prospective cohort study.

SUBJECTS AND METHODS

Subjects were 485 participants in the Sorbinil Retinopathy Trial, a randomized trial of aldose reductase inhibition among patients aged 18 to 56 years with type 1 diabetes mellitus (duration of 1 to 15 years) and no or only mild retinopathy. Retinopathy progression, assessed by seven-field stereoscopic fundus photography, was defined as worsening by two or more levels on a standardized grading scale at the end of follow-up (median, 41 months).

RESULTS

The relative risks for retinopathy progression according to successively greater quintiles of total glycosylated hemoglobin level at baseline, after adjusting for age, diabetes duration, sorbinil assignment, and other variables, were 1.0, 2.0, 1.6, 3.7, and 4.4 (P trend <0.0001). Risk increased with greater baseline diastolic blood pressure: 1.0 for <70 mm Hg, 1.2 for 70 to 79 mm Hg, and 1.8 for > or =80 mm Hg (P for trend = 0.04). Diastolic blood pressure was a significant risk factor for progression in participants with mild baseline retinopathy (P for trend <0.02) but not in those without retinopathy at entry. Systolic blood pressure, by comparison, was not associated with progression. Baseline total cholesterol level was a marginally significant predictor of retinopathy progression when examined as a categorical variable (relative risks for increasing quartiles; 1.0, 1.6, 1.8, 1.9; P for trend = 0.03) but not when it was examined as a continuous variable or when hypercholesterolemic patients were compared with those with normal levels. Furthermore, when cholesterol levels were updated in subsequent visits, it was not a significant predictor of progression, and low density lipoprotein (LDL) cholesterol levels did not predict progression no matter how analyzed. Smoking was not associated with progression of retinopathy.

CONCLUSIONS

Levels of hyperglycemia and diastolic blood pressure predicted progression of retinopathy in type 1 diabetes mellitus. We found only a suggestion of an association between total cholesterol level (but not of LDL cholesterol level) and progression of retinopathy; resolution of this issue will require additional studies with larger sample sizes and longer follow-up.

Long-term follow-up of and underlying medical conditions in patients with diabetic exudative maculopathy

Recent reports of risk factors for and survival of patients with diabetic retinopathy do not include exudative maculopathy as a separate entity. We therefore studied a group of hypertensive Type II diabetic subjects with exudative maculopathy (n = 26) compared to a carefully matched hypertensive diabetic comparison group without retinopathy (n = 26) over seven years. Diabetic maculopathy patients had higher mean diastolic blood pressure (101.6 +/- 14 versus 94.8 +/- 10 mmHg, p less than 0.05), serum cholesterol (6.65 +/- 2.2 versus 5.9 +/- 1.31 mmol/l), HDL2 subfraction levels (0.46 +/- 0.23 versus 0.32 +/- 0.18 mmol/l) and a higher prevalence of hyperlipidaemia (54% versus 35%) compared to the comparison group. After seven years, the maculopathy group showed a strikingly higher prevalence of renal failure and nephrotic syndrome (42% versus 8%, p less than 0.05) and of macroproteinuria (58% versus 15%, p less than 0.01) compared to the comparison group. Mortality and cardiovascular disease event rate was 12% and 38% in the maculopathy and 15% and 31% respectively in the comparison group. We conclude that although mortality is not significantly higher in diabetics with exudative maculopathy, proteinuria, renal failure and nephrotic syndrome may be associated features on long term follow-up. Hypertension and hypercholesterolaemia may also be risk factors in the development of diabetic maculopathy.

Cotton-wool spots and retinal light sensitivity in diabetic retinopathy

In 14 eyes of 14 patients with diabetic retinopathy the light sensitivity of retinal cotton-wool spots was studied by computerised perimetry, and the visual field data were accurately correlated with the corresponding morphology as seen on fundus photographs and fluorescein angiograms. In 12 of the eyes the examinations were repeated within one year in order to follow changes in retinal light sensitivity during the evolution of the lesions. Retinal cotton-wool spots were in all eyes associated with localised non-arcuate scotomata in the visual field. In four eyes the cotton-wool spots disappeared within three months of the first examination, and in two of these cases the corresponding scotomata disappeared together with the morphological lesions. In eight eyes the cotton-wool spots (and the corresponding scotomata) had not resolved one year after the first examination. The mean blood pressure showed no significant difference between the patients in whom the lesions resolved within three months and the patients in whom the lesions persisted longer.

The Wisconsin Epidemiologic Study of Diabetic Retinopathy. VII. Diabetic nonproliferative retinal lesions

The prevalences of hard exudates, soft exudates, intraretinal microvascular abnormalities (IRMAs), and venous beading and their relationships to demographic and other characteristics were examined in a population-based study in southern Wisconsin. For participants whose age at diagnosis was less than 30 years and who were taking insulin (N = 996), hard exudates were found in 24.2%, soft exudates in 15.3%, IRMAs in 16.5%, and venous beading in 7.0% of the population. For participants whose age at diagnosis was 30 years or older and who were taking insulin (N = 674), hard exudates were found in 28.3%, soft exudates in 15.5%, IRMAs in 8.8%, and venous beading in 3.2%. For older-onset persons not taking insulin (N = 696), hard exudates were found in 9.4%, soft exudates in 5.4%, IRMAs in 2.6%, and venous beading in 0.9% of the population. The severities of the lesions were found to be consistently associated with longer duration of diabetes in younger-onset persons and the presence of proteinuria in older-onset persons.

Retinal cotton-wool spots: an early finding in diabetic retinopathy?

Five insulin dependent diabetic patients are reported on who had a few small retinal cotton-wool spots or 'soft exudates' either totally isolated or associated with fewer than 10 microaneurysms. These observations suggest that cotton-wool spots may be an early finding in diabetic retinopathy. Significant biological abnormalities in these patients were high levels of glycosylated haemoglobin and mild increases in thrombin generation, indicating slight activation of the coagulation system. The possible significance of these clinical and biological findings is discussed.

Effects of intensified insulin treatment on various lesions of diabetic retinopathy

Mild background retinopathy was studied prospectively during long-term strict blood glucose control in insulin-dependent diabetes mellitus. Forty-five subjects (21 women and 24 men with a mean age of 26.3 years and a mean duration of diabetes of 12.8 years) were randomly assigned to continuous subcutaneous insulin infusion, multiple injections, and conventional two-injection treatment. Eyes were examined two months before treatment, at the beginning of treatment, and after three, six, and 12 months. A progressive deterioration was found in the two-injection group during the study, but no significant changes were found in patients receiving multiple injections. A transient deterioration occurred after three months of continuous subcutaneous insulin infusion. Soft exudates appeared in 50% of the patients on the two intensified regimens, but no exudates were found in patients given conventional treatment. The morphologic changes seemed to be related to a large and rapid decrease in mean blood glucose or to an increased frequency of hypoglycemia, or both.

Diabetes and arterial hypertension

The epidemiology, pathogenesis, significance and management of hypertension in diabetic subjects are discussed. In Type 1 diabetes the presence of diastolic hypertension is closely related to the presence of diabetic nephropathy, from the stage of persistent proteinuria onwards. There may also be some elevation of systolic pressure. The apparent increased prevalence of hypertension in Type 2 diabetes is largely explicable, directly or indirectly, by obesity but there may be an excess of systolic hypertension among elderly patients. Hypertension in the diabetic population is associated with an increased incidence of both microvascular and macrovascular complications, but whether the high blood pressure is causal is not clear. The possible roles of sodium and insulin, the renin-angiotensin system, catecholamines and physical factors are explored. All current antihypertensive agents have additional limitations and disadvantages when used in diabetic patients: diuretics and beta-blockers are probably the initial drugs of choice. Only in the case of diabetic nephropathy is there yet reasonable evidence of antihypertensive treatment reducing the rate of progression of the disease.

Low density lipoprotein cholesterol: an association with the severity of diabetic retinopathy

Diurnal profiles of total and lipoprotein cholesterol and triglycerides were measured in 11 insulin-dependent diabetic subjects without retinopathy, 10 with background and 10 with proliferative retinopathy. The groups were closely matched for age and duration of diabetes. Total cholesterol levels were higher in patients with proliferative (5.6 +/- 0.5 mmol/l) than background (5.1 +/- 0.7 mmol/l) or no retinopathy (4.6 +/- 0.8 mmol/l, trend test; p less than 0.003), due to raised levels of low density lipoprotein (LDL) cholesterol (3.8 +/- 0.9, 3.2 +/- 0.6 and 2.8 +/- 0.8 mmol/l respectively; p less than 0.02). High density lipoprotein (HDL) levels were similar in patients with and without retinopathy and HDL/LDL ratios were lower with more severe retinopathy (p less than 0.025). Cholesterol levels were similar in diabetic subjects without retinopathy and in 12 normal subjects. Triglyceride levels were not related to retinopathy and no measure of plasma lipids correlated with HbA1 or 24-h mean plasma glucose. Total and LDL cholesterol were weakly inversely correlated with creatinine clearance but the association with retinopathy was independent of this effect.

Macular and perimacular vascular remodelling sickling haemoglobinopathies

The posterior pole vasculature of 100 patients with different sickling haemoglobinopathies was studied prospectively over a period of three years. Various abnormalities of the posterior pole vasculature were seen in 29 per cent of the patients. Continuous remodelling of the macular and perimacular vasculature occurred. Visual acuity was variably affected and sometimes remained intact.

Pathological changes in the central and peripheral nervous system of young long-term diabetics : I. Diabetic encephalopathy

A study of the clinical observations and the neuropathological findings in the brain of 16 juvenile diabetics dying of diabetic angiopathy after many years of diabetes is presented. A characteristic histological pattern was observed in all the cases consisting of diffuse degenerative abnormalities of the brain tissue, often with severe pseudocalcinosis or with atrophy of the dentate nucleus, demyelinisation of the cranial nerves, fibrosis of the leptomeninges and angiopathy. The degenerative changes were so pronounced that a dual pathogenesis seems likely; viz. an ischemia caused by the angiopathy and a primary diabetic abnormality of the brain tissue. The clinical symptoms of cerebral disease varied from insignificant to pronounced. A correlation was found between the symptoms and the number of areas of softening in the brain. The histological pattern differs from that seen in other clinical conditions and justifies the term diabetic encephalopathy.

Fluoresceinretinography: exudates and microaneurysms

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