Current Management of Diabetic Retinopathy

Caroline R Baumal, Jay S. Duker

• Publisher: Elsevier
• Year: 2017
• ISBN:
  9780323549493
• Topic: Médecine
• Subtopic: Ophtalmologie et optométrie

Stay current with recent progress in the field of diabetic retinopathy management with this practical resource by Drs. Caroline R. Baumal and Jay S. Duker. Concise, highly illustrated coverage includes summaries of the latest evidence and expert guidance on the rationale for each therapeutic option.

• Features a wealth of information for ophthalmologists, retinal specialists, and trainees on current management of this increasingly common condition.
• Covers how to select the best course of action between drug, laser, or surgical treatment and how to achieve optimal results.
• Includes high-quality images that detail before and after treatment, including OCT.
• Consolidates today's available information and guidance on diabetic retinopathy management into one convenient resource.

Section II

Treatment Of Diabetic Retinopathy

Outline

Chapter 6. Effect of Modifiable Risk Factors on the Incidence and Progression of Diabetic Retinopathy

Chapter 7. Anti–Vascular Endothelial Growth Factor Therapy for Diabetic Eye Disease

Chapter 8. Corticosteroid Therapy for Diabetic Retinopathy

Chapter 9. Laser Treatment of Diabetic Retinopathy

Chapter 10. Surgical Treatment of Diabetic Retinopathy

Chapter 11. Treatment of Diabetic Retinopathy in Pregnancy

Chapter 12. Novel Treatments for Diabetic Retinopathy

Chapter 6

Effect of Modifiable Risk Factors on the Incidence and Progression of Diabetic Retinopathy

Michael D. Tibbetts, MD

Abstract

The modifiable risk factors for diabetic retinopathy include glycemic control, hypertension, inhibition of the renin-angiotensin system, serum lipid levels, dietary intake of omega-3 fatty acids, physical activity, sedentary behavior, obesity, aspirin therapy, and smoking. Glycemic control is the most important modifiable risk factor for diabetic retinopathy. An exponential relationship between hemoglobin A1c (HgbA1c) and diabetic retinopathy progression has been demonstrated in multiple clinical trials. A target HgbA1c <7% is associated with a lower incidence and progression of retinopathy. Hypertension is also a primary risk factor due to the microvascular damage that may exacerbate the small vessel injury caused by elevated glucose levels. Blood pressure (BP) control can reduce the risk of retinopathy, but there may be a floor effect for systolic BP less than 120 mm Hg. Inhibition of the renin-angiotensin system by angiotensin converting enzyme inhibitors or angiotensin receptor blockers has been shown to reduce the progression of diabetic retinopathy. The reduction of lipid levels can reduce hard exudates and microaneurysms in diabetic retinopathy. In addition, multiple studies demonstrate that obesity increases the risk of retinopathy. There is also evidence that increased physical activity, reduced sedentary behavior, and increased dietary intake of omega-3 fatty acids may reduce retinopathy progression. Aspirin therapy and smoking are not linked to an increased risk of retinopathy. Eye care providers must communicate effectively with the patient's diabetes care team to encourage the management of systemic risk factors that can alter the course of the disease.

Keywords

Diabetes Control and Complications Trial (DCCT); Glycemic control; Hypertension; Renin-angiotensin system; Risk factors; Serum lipids

Introduction

The identification of potential risk factors that affect the development and progression of diabetic retinopathy or response to therapy is an active area of investigation. Some of these risk factors are modifiable, such as lifestyle choices, whereas others, such as disease duration, are not. The duration of diabetes mellitus has been identified as a major risk factor associated with the development as well as the severity of diabetic retinopathy. This has been confirmed by multiple studies for individuals with both type 1 and type 2 diabetes. For patients with type 1 diabetes, after 5 years of diabetes duration, 25% will have some evidence of retinopathy, after 10 years, 60% have retinopathy, and after 15 years 80% have retinopathy.^1–3 Proliferative diabetic retinopathy (PDR) may be present in 50% of patients with type 1 diabetes (often 30 years and younger) who have the disease for 20 or more years.² PDR develops in 25% of individuals who have type 2 diabetes for 25 years or more and in only 2% of those with diabetes less than 5 years.¹ In patients with type 2 diabetes over the age of 30 years who have the diagnosis for less than 5 years, the risk of diabetic retinopathy increases for those patients who require insulin. Forty percent of such patients have retinopathy, whereas 24% of patients not taking insulin have retinopathy.

In the current era in which ophthalmologists have a variety of tools to treat diabetic macular edema (DME) and PDR, the assessment of the modifiable risk factors that can reduce the onset and severity of diabetic retinopathy may be overlooked. The anti–vascular endothelial growth factor (anti-VEGF) medications, in particular, can improve vision in patients with DME, induce regression of neovascularization, and also reduce the diabetic retinopathy severity score (DRSS).^4,5 Although anti-VEGFs may improve the retinopathy, these medications given by intravitreal injection do not affect the course of nephropathy, neuropathy, and other systemic sites of microvascular injury nor do they mitigate the risks of myocardial infarction and stroke, which are the leading cause of death in diabetic patients. Eye care providers must communicate effectively with the patient’s care team, including the primary care physician and endocrinologist, to encourage the management of systemic risk factors that can alter the course of the disease.

This chapter systematically reviews the evidence for modifiable risk factors that influence the onset and severity of retinopathy (Tables 6.1 and 6.2). The weight of the evidence varies for each factor and may not apply to every diabetic patient.

The modifiable risk factors for diabetic retinopathy include:

• Glycemic control

• Hypertension

• Inhibition of the renin-angiotensin system (RAS)

• Serum lipid levels

• Dietary intake of omega-3 fatty acids

• Physical activity and sedentary behavior

• Obesity

• Aspirin therapy

• Smoking

Glycemic Control

Glycemic control is the most important modifiable risk factor for diabetic retinopathy.⁶ Numerous reports based on both clinical trials and epidemiologic studies have demonstrated that glycemic control forecasts the incidence and progression from earlier to later stages of diabetic retinopathy. In fact, glycemic control is a more important factor than the duration of diabetes to predict progression to more advanced stages of diabetic retinopathy.⁷ The mechanism by which hyperglycemia induces diabetic retinopathy is multifactorial, with glycosylated end products, oxidative stress, overactivation of protein kinase C, and upregulation of VEGF and other biochemical pathways disrupting vascular homeostasis and inducing retinal vascular injury. Chronic hyperglycemia causes retinal endothelial dysfunction and subsequent ischemia that can lead to proliferative vascular changes with neovascularization.

Table 6.1

Risk Factors for Diabetic Retinopathy

Risk Factors	Modifiable Risk Factors
• Duration of diabetes mellitus • Age • Genetic predisposition • Ethnicity • Gender •...