- •Foreword
- •Preface
- •Contents
- •Contributors
- •Acronyms
- •1.1 Introduction
- •1.2 Epidemiology
- •1.3 Risk Factors
- •1.3.1 Duration of Diabetes Mellitus
- •1.3.2 Glycemic Control
- •1.3.3 Hypertension
- •1.3.4 Ethnic Differences
- •1.3.5 Obesity
- •1.3.6 Socioeconomic Status
- •1.3.7 Other Risk Factors
- •1.4 Pathophysiology
- •Conclusion
- •References
- •2: Non-proliferative Diabetic Retinopathy
- •2.1 Clinical Overview
- •2.1.1 Clinical Findings
- •2.1.2 Classification of NPDR
- •2.1.3 Atypical Forms of NPDR
- •2.2 Diagnostic Tools
- •2.2.1 Telemedicine
- •2.2.2 Fundus Photography
- •2.2.3 Fluorescein Angiography
- •2.2.4 Ultrasonography
- •2.2.5 Optical Coherence Tomography
- •2.2.6 Adaptive Optics Scanning Laser Ophthalmoscope
- •2.2.7 Multifocal Electroretinogram
- •2.2.8 Pattern Visual Evoked Potentials
- •2.2.9 Other Diagnostic Tools
- •2.3 Present Therapies
- •2.3.1 Primary Interventions
- •2.3.1.1 Glycemic Control
- •2.3.1.2 Blood Pressure Control
- •2.3.1.3 Lipid-Lowering Therapy
- •2.3.2 Secondary Interventions
- •2.3.2.1 Protein Kinase C Inhibitors
- •2.4 Evolving Algorithms
- •2.4.1 Screening
- •2.4.2 Laser Photocoagulation
- •2.5 New Frontiers
- •References
- •3: Diabetic Macular Edema
- •3.1 Clinical Overview
- •3.1.1 Clinical Findings
- •3.1.2 Biomicroscopic Classification of DME
- •3.2 Diagnostic Tools
- •3.2.1 Fluorescein Angiography
- •3.2.2 Optical Coherence Tomography
- •3.2.3 Fundus Photography
- •3.2.4 Microperimetry
- •3.2.5 Multifocal Electroretinogram
- •3.2.6 Other Imaging Under Investigation
- •3.3 Present Therapies
- •3.3.1 Laser Photocoagulation
- •3.3.2 Intravitreal Pharmacotherapies
- •3.3.2.1 Intravitreal Steroids
- •3.3.2.2 Intravitreal Anti-VEGF
- •3.3.3 Pars Plana Vitrectomy
- •3.4 Evolving Algorithms
- •3.4.1 Therapeutic Algorithms
- •3.4.2 Factors Associated with Favorable Response to the Therapy
- •3.4.3 Treatment of DME Associated with Macular Ischemia
- •3.5 New Frontiers
- •References
- •4: Proliferative Diabetic Retinopathy
- •4.1 Clinical Overview
- •4.1.1 Clinical Findings
- •4.1.2 Classification of PDR
- •4.2 Diagnostic Tools
- •4.2.1 Fluorescein Angiography
- •4.2.2 Fundus Photography
- •4.2.3 Ultrasonography
- •4.2.4 Optical Coherence Tomography
- •4.2.5 Perimetry
- •4.2.6 Further Diagnostic Tools
- •4.3 Present Therapies
- •4.3.1 Panretinal Laser Photocoagulation
- •4.3.2 Intravitreal Injections
- •4.3.2.1 Intravitreal Steroids
- •4.3.2.2 Intravitreal Anti-VEGF Agents
- •4.4 Evolving Algorithms
- •4.5 New Frontiers
- •References
- •5.1 Introduction
- •5.2 Pathophysiology
- •5.3 Neovascular Glaucoma
- •5.4 Tractional Retinal Detachment
- •5.5 Treatment
- •5.5.1 Panretinal Laser Photocoagulation
- •5.5.2 Pars Plana Vitrectomy and Endophotocoagulation
- •5.5.4 Silicone Oil Tamponade
- •5.5.4.1 Viscodissection
- •Conclusion
- •References
1 Epidemiology, Risk Factors, and Pathophysiology of Diabetic Retinopathy |
7 |
|
|
obesity or high waist circumference is an independent risk factor for DR in individuals with type 1 DM [51]. Dirani and coworkers showed that BMI and neck circumference were independently associated with the presence and severity of DR. The risk of having DR increased threefold with obesity [53]. The WESDR data suggested that obesity (BMI 31.0 kg/m2 for men and 32.1 kg/m2 for women) increases the severity of DR and its progression, but this result was not statistically significant [54].
The pathophysiologic mechanisms linking obesity and DR are not clear. In animal diabetic models, inflammatory and pro-angiogenic markers are upregulated with obesity [55]. Obesity is also associated with hyperlipidemia and hypertension, which in themselves are risk factors for DR.
The META-EYE study showed a trend towards a higher prevalence of VTDR in diabetic patients with cholesterol levels ≥4.0 mmol/L [3]. Total serum cholesterol was associated with a higher prevalence of DME in this study.
Treatment with fenofibrate, a triglyceride-lowering medication (in combination with statins in many cases), has been shown to decrease the progression of DR by 30–40 % over 4–6 years in individuals with type 2 DM in the FIELD and ACCORDEYE studies [56, 57]. The mechanism is unclear, and the effect is independent of the serum lipid levels [57]. Fenofibrate is a peroxisome proliferator-activated receptor (PPAR) α-agonist and has anti-inflammatory and antioxidant properties. It promotes expression and activation of antioxidant enzymes, such as superoxide dismutase and glutathione peroxidase [58] and inhibits leukostasis and retinal vascular leakage [59]. PPAR-α agonists also inhibit VEGF receptor 2 (VEGFR2) expression and downregulate VEGF expression [60, 61].
1.3.6Socioeconomic Status
Health disparities can be associated with differences in socioeconomic status. The full impact of socioeconomic status on diabetes is, however, not known. Many factors such as life style, health behavior, and health-care system access may be confounding. Higher socioeconomic groups in developing countries may lead a more sedentary lifestyle and have a higher caloric diet and be more obese than persons of lower socioeconomic status. This difference may negate the benefits of better medical access for the rich [5, 6, 62].
1.3.7Other Risk Factors
Although HgA1c, blood pressure, and total serum cholesterol are important modifiable risk factors for the development of DR, they account for only a small proportion (~10 %) of the risk [63, 64]. As pointed out by Antonetti et al. [65], other factors include sleep apnea [66], non-alcoholic fatty liver disease [67], and serum prolactin [68], adiponectin [50], and homocysteine [69].