18 Diabetic Retinopathy and Diabetic Macular Edema

Abstract

Diabetic retinopathy and diabetic macular edema result from chronic damage to the neurovascular structures of the retina. The pathophysiology of retinal damage remains uncertain but includes metabolic and neuroinflammatory insults. These mechanisms are addressed by intensive metabolic control of the systemic disease and by the use of ocular anti-inflammatory agents, including vascular endothelial growth factor inhibitors and corticosteroids. Improved understanding of the ocular and systemic mechanisms that underlie diabetic retinopathy will lead to improved means to diagnose and treat retinopathy and better maintain vision. This chapter summarizes the pathogenesis, risk factors, diagnosis, signs and symptoms, and treatment options for diabetic retinopathy (DR) and diabetic macular edema (DME). The complex nature of DR has led to a variety of therapies, but treatments for DR and DME are still challenging, particularly in the stages when retinopathy is mild and patients retain good vision. Diabetic Retinopathy Prevalence DR is one of the major complications of diabetes and is a leading cause of blindness and vision impairment. Approximately 75% of persons suffering from type 1 diabetes develop retinopathy, while approximately 50% of persons with type 2 diabetes may develop retinopathy [1], and approximately 25% of persons with diabetes may develop macular edema. During the next two decades, over 360 million people worldwide are projected to have diabetes and its complications [2]. Fortunately, the prevalence of severe retinopathy and nephropathy in patients with type 1 diabetes has diminished over the past 35 years due to improved medical care [3], but the recent epidemic of type 2 diabetes requires a new understanding of the biology of DR and our approach to its prevention and treatment. Approximately 500,000 persons in the United States have clinically significant DME, with an annual incidence of 75,000, and approximately 700,000 have proliferative DR, with an annual incidence of 65,000 [4]. Risk Factors The clinical risk factors for DR have long been recognized to include diabetes severity and duration, hypertension, presence of other complications, anemia, hyperlipidemia, insulin resistance and deficiency, and a family history of DR (reviewed by Antonetti et al. [5] and