Clinical Signs Of Diabetic Retinopathy Research Articles

The 4a/4a genotype of the VNTR polymorphism for endothelial nitric oxide synthase (eNOS) gene predicts risk for proliferative diabetic retinopathy in Slovenian patients (Caucasians) with type 2 diabetes mellitus

Thus far only a limited number of studies examined the association between endothelial nitric oxide synthase (eNOS) polymorphisms and proliferative diabetic retinopathy (PDR). In this report, two polymorphisms in the eNOS gene have been investigated, namely the 894G>T (Glu298Asp) and a 27 bp VNTR (4b/4a), to assess their possible relationships to PDR among Slovenian (Caucasians) type 2 diabetic patients. This cross-sectional case-control study enrolled 577 unrelated Slovenian subjects (Caucasians) with type 2 diabetes mellitus. The case group consisted of 172 patients with PDR and the control group had 405 patients who had no clinical signs of diabetic retinopathy (DR) but did have type 2 diabetes for more than 10 years' duration. Genotyping of eNOS polymorphisms was carried out with conventional and real-time PCR assays. A significantly higher frequency of the eNOS minor "4a" allele was found in patients with PDR than in controls (23.6 versus 17.7%, p = 0.01). Moreover, the univariate analysis showed a significant association of the 27 bp VNTR 4a/4a genotype and PDR in the recessive model. The odds ratio (OR) of PDR for the 4a/4a genotype to 4b/4a plus 4b/4b was 2.9 (95% CI 1.3-6.2, p = 0.005). Further, the presence of 4a/a genotype was associated with a 3.4-fold (95% CI 1.4-8.6, p = 0.009) increased risk for PDR while adjusted for other risk factors. This is the first study to implicate eNOS 4a/4a homozygous deletion, and hence the "4a" allele, as the genetic risk factors for PDR in Caucasians.

A Segment based Technique for Detecting Exudate from Retinal Fundus Image

Diabetic retinopathy is a disorder that accounting as a root cause of uncorrectable vision loss for diabetic patients. It is due to the damaging of blood vessels that nourish the retina. However, earlier detection and treatment through regular screening, blindness can be avoided. In order to lessen the cost of these screenings, modern image processing techniques are used to voluntarily detect the existence of abnormalities in the retinal images acquired during the screenings. The earliest clinical signs of diabetic retinopathy are microaneurysms, small out-pouching from retinal capillaries, and dot intra-retinal Hemorrhages. Exudates are a major indicator of diabetic retinopathy that can possibly be quantified automatically. Patients having these signs are present in type1 stage of diabetic retinopathy also called NPDR (Non-Proliferative Diabetic Retinopathy). This paper implements a method that identifying the feature of exudates from the image using segment based feature extraction. Here, classification into various stages of NPDR is based on their pixels intensity and frequency from the retinal fundus image. A serious of experiments for extracting the feature is performed with the use of effective image processing techniques. To get these feature value from fundus retinal image various techniques like morphological pre-processing, image boundary tracing, adaptive threshold using Otsu methodology, Optic disk localization are implemented. The SVM classifier uses features extracted by combined 2DPCA instead of explicit image features as the input vector Combined 2DPCA is proposed and then for acquiring higher accuracy of classification we can use virtual SVM. Experimental evaluation on the publicly available dataset DRIVE demonstrates the improved performance of the proposed method for automatic detection of Exudates. These automatically detected exudates are validated by comparing with expert ophthalmologists’ hand-drawn ground-truths. The overall sensitivity of proposed method is 97.1% for the classifier and the specificity is of 98.3%. So, by using this tool Specialist gets support in screening a detection of early changes causing Diabetic Retinopathy and hence timely intervention leading to reduced DR related blindness.

A1/A2 polymorphism of the glycoprotein IIIa gene and diabetic retinopathy in Caucasians with type 2 diabetes

A PlA1/A2 polymorphism of glycoprotein IIIa is known to be involved in the pathogenesis of arterial thrombosis, myocardial infarction, stroke and type 2 diabetes, but there is no evidence of association with diabetic retinopathy. The aim of this study was to examine the role of the PlA1/A2 polymorphism of the glycoprotein IIIa gene in the development of diabetic retinopathy in Caucasians with type 2 diabetes. Cross-sectional case-control study. Totally 222 patients with diabetic retinopathy and 120 diabetic subjects without clinical signs of diabetic retinopathy from the Eye Clinic, University Medical Centre Ljubljana were enrolled in the study. Fundus examination and blood biochemical analysis were performed. The polymerase chain reaction and restriction fragment length polymorphism were used. The total cholesterol, triglyceride, high-density lipoprotein levels, fasting blood glucose and HbA(1c) were measured, and the genotypes of the PlA1/A2 polymorphism were determined. Patients with diabetic retinopathy had earlier onset, longer duration of type 2 diabetes and a higher incidence of insulin therapy compared to the diabetic patients without diabetic retinopathy. A significantly lower frequency of the A2A2 genotype of glycoprotein IIIa was found in diabetic patients with retinopathy compared to those without retinopathy (odds ratio = 0.49, 95% confidence interval = 0.28-0.89; P = 0.018). The A2A2 genotype of the glycoprotein IIIa polymorphism was associated with lower risk for diabetic retinopathy in Caucasians with type 2 diabetes. Further studies are needed to elucidate its protective role in the development of diabetic retinopathy in Caucasians.

Diabetic retinopathy management by Australian optometrists

To survey the current diabetic retinopathy screening and management practices of Australian optometrists following the release of the 1997 National Health Medical Research Council Diabetic Retinopathy Management Guidelines. Cross-sectional national survey, primary care setting. 1000 Australian optometrists across different states. A self-administered questionnaire was sent to 1000 optometrists across all states during 2007/2008. Use of retinal camera, screening practices/attitudes and behaviour in diabetic retinopathy management. 568 optometrists (57%) responded to the survey. Patients' unpreparedness to drive post dilation (51%) and the fear of angle closure glaucoma (13%) were the two main barriers to optometrists not performing dilated ophthalmoscopy. Those who had strong desire to screen for diabetic retinopathy were more likely to use a retinal camera (p<0.005). Use of a retinal camera was significantly associated with an increased confidence in detecting clinical signs of diabetic retinopathy including macular oedema (P<0.001). Optometrists who read the guidelines at least once were 2.5-times (P<0.001) more likely to have confidence in detecting macular oedema than those who had never read the guidelines. Although they may be confident in diagnosis, and may use retinal cameras for screening, nearly 60% of optometrists would not refer patients with macular oedema to an ophthalmologist. Despite their self-reported desire for involvement in diabetic retinopathy, the management of macular oedema by Australian optometrists needs improvement. The use of retinal cameras and promotion of the 2008 NHMRC guidelines should be encouraged to improve overall optometric diabetic retinopathy management, particularly with macular oedema.

Color vision impairment in type 2 diabetes assessed by the D‐15d test and the Cambridge Colour Test

Color vision impairment emerges at early stages of diabetes mellitus type 2 (DM2) and may precede diabetic retinopathy or the appearance of vascular alterations in the retina. The aim of the present study was to compare the evaluation of the color vision with two different tests - the Lanthony desaturated D-15d test (a traditional color arrangement test), and the Cambridge Colour Test (CCT) (a computerized color discrimination test) - in patients diagnosed with DM2 without clinical signs of diabetic retinopathy (DR), and in sex- and age-matched control groups. Both color tests revealed statistically significant differences between the controls and the worst eyes of the DM2 patients. In addition, the degree of color vision impairment diagnosed by both tests correlated with the disease duration. The D-15d outcomes indicated solely tritan losses. In comparison, CCT outcomes revealed diffuse losses in color discrimination: 13.3% for best eyes and 29% for worst eyes. In addition, elevation of tritan thresholds in the DM2 patients, as detected by the Trivector subtest of the CCT, was found to correlate with the level of glycated hemoglobin. Outcomes of both tests confirm that subclinical losses of color vision are present in DM2 patients at an early stage of the disease, prior to signs of retinopathy. Considering the advantages of the CCT test compared to the D-15d test, further studies should attempt to verify and/or improve the efficiency of the CCT test.

Local and genetical determinants of vascular endothelial growth factor in vision threating proliferative diabetic retinopathy

Abstract Purpose To search for the association between the –634 C/G polymorphism of the VEGF gene and vision threating proliferative diabetic retinopathy (PDR) and to determine whether vitreous levels of VEGF were affected by genetic factors. Methods In this cross sectional case‐control study 349 unrelated Slovene subjects (Caucasians) with type 2 diabetes mellitus were enrolled: 206 patients with vision threating PDR in whom vitrectomy was performed, and the control group of 143 subjects with type 2 diabetes of duration of more than 10 years who had no clinical signs of diabetic retinopathy. In 68 out of 206 patients with PDR (71 eyes) vitreous fluid samples (0.3 ml) were obtained by vitreoretinal surgery. Results The –634 C/G VEGF gene polymorphism was not associated with PDR. Moreover, significantly higher vitreous levels of VEGF were demonstrated in diabetics with the CC genotype compared to those with the other (CG + GG) genotypes. Conclusion Despite the effect of the –634 C/G VEGF gene polymorphism on vitreous levels of VEGF in PDR, it failed to contribute to the genetic susceptibility to PDR.

K469E polymorphism of the intracellular adhesion molecule 1 gene is associated with proliferative diabetic retinopathy in Caucasians with type 2 diabetes

In proliferative diabetic retinopathy (PDR) increased levels of cytokines, inflammatory cells and angiogenic factors are present.These factors increase the expression of cellular adhesion molecules (CAMs)The objective of this study was to investigate the association between the polymorphisms of the ICAM-1 gene (K469E, G241A) and the development of PDR among patients with type 2 diabetes in the Slovenian population (Caucasians). For the purpose, 195 subjects with type 2 diabetes with PDR were compared with 143 subjects with type 2 diabetes of duration of more than 10 years who had no clinical signs of diabetic retinopathy. We analysed serum ICAM levels in 54 subjects with type 2 diabetes and 25 subjects without diabetes. A significantly higher frequency of the EE genotype of the K469E polymorphism of the ICAM-1 was found in the patients with PDR compared with those without diabetic retinopathy (OR = 2.0, 95% confidence interval [CI] = 1.1-3.5; P = 0.013), whereas the G241A polymorphism of the ICAM-1 gene failed to yield an association with PDR. Moreover, significantly higher sICAM-1 serum levels were demonstrated in diabetics with the EE genotype compared with those with the other (EK + KK) genotypes (918 +/-104 vs. 664 +/-209 microg/L; P = 0.001). The G241A polymorphism of the ICAM-1 gene, on the hand, failed to affect sICAM-1 serum levels in diabetics. We may conclude that the EE genotype of the K469E polymorphism of the ICAM-1 might be a risk factor for PDR in the Slovenian population (Caucasians) with type 2 diabetes.

Polymorphisms in the promoter region of the basic fibroblast growth factor gene and proliferative diabetic retinopathy in Caucasians with type 2 diabetes

Basic fibroblast growth factor (bFGF) expression is implicated in proliferative diabetic retinopathy (PDR). The aim of this study was to investigate the association of genetic polymorphisms (-553T/A, -834T/A and -921C/G) in the promoter region of the bFGF gene with PDR in patients with type 2 diabetes. The second aim was to determine whether serum levels of bFGF are affected by genetic factors. In this cross-sectional case-control study 313 unrelated Caucasians (Slovene population) with type 2 diabetes mellitus were enrolled: 206 patients with PDR and the control group of 107 subjects with type 2 diabetes of duration of more than 10 years who had no clinical signs of diabetic retinopathy. We analysed serum bFGF levels in 78 subjects with type 2 diabetes and 25 subjects without diabetes. The AT genotype of the -553T/A polymorphism was present in 31 (15.0%) PDR patients and in seven (6.5%) controls (P = 0.03, odds ratio = 2.0, 95% confidence interval = 1.0-3.9). The AT genotype of the -834T/A polymorphism was present in 12 (5.8%) PDR patients and in 15 (14.0%) controls (P = 0.01, odds ratio = 0.4, 95% confidence interval = 0.2-0.8). Significantly higher bFGF serum levels were demonstrated in diabetics with the AT genotype of the -553 polymorphism compared with diabetics with the TT genotype, whereas the -834 and -921 polymorphisms failed to affect serum bFGF levels. We may conclude that the AT genotype of the 553 T/A polymorphism was associated with PDR in Caucasians with type 2 diabetes, therefore it might be used as a genetic marker of PDR in Caucasians, whereas carriage of the AT genotype of the -834 T/A polymorphism might decrease PDR risk.