title: Etiology and natural history of diabetic retinopathy: an overview.
abstract: OBJECTIVE
  The morbidity and mortality from and economic impact of diabetes mellitus in the United States, pathogenesis of microvascular diabetic complications, contribution of poor long-term glycemic control to risk for diabetic retinopathy and other microvascular complications, prevalence of diabetic retinopathy, methods for measuring visual acuity, and manifestations of disease progression and etiology of blindness in patients with diabetic retinopathy are discussed.
  
  
  CONCLUSIONS
  Diabetic retinopathy and other microvascular and macrovascular complications of diabetes cause considerable morbidity and mortality and have a large economic impact in the United States. Patients with poor long-term glycemic control are more vulnerable to diabetic retinopathy than to other microvascular complications of diabetes. Diabetic retinopathy is the third leading cause of all cases of blindness in the United States and the leading cause of new cases in adults. Retinopathy is already present at the time of diagnosis in 20% of patients with type 2 diabetes. Retinopathy and other micro-vascular complications are attributed to chronic hyperglycemia, vascular damage and leakage, edema, capillary basement membrane thickening, neovascularization, hemorrhage, and ischemia. Measurements of visual acuity loss are expressed in terms of the distance at which a person with normal vision can see what the test subject can see from 20 feet away. Diabetic retinopathy begins as nonproliferative abnormalities and progresses to proliferative diabetic retinopathy. Macular edema can develop at any time in the progression of diabetic retinopathy. Macular ischemia, retinal and vitreous hemorrhage, and retinal detachment are the primary causes of blindness in patients with diabetic retinopathy.
  
  
  CONCLUSIONS
  Diabetic retinopathy is a costly and progressive condition associated with chronic hyperglycemia. It is potentially vision-threatening.
authors.affiliation: University of California, San Diego, Skaggs School of Pharmacy and Pharmaceutical Sciences, 9500 Gilman Drive, La Jolla, CA 92093, USA. cmmorello@ucsd.edu
authors.forename: Candis M
authors.initials: CM
authors.lastname: Morello
mesh_terms: D002908:Chronic Disease; D003920:Diabetes Mellitus / Q000175:diagnosis* / Q000191:economics; D003930:Diabetic Retinopathy / Q000175:diagnosis* / Q000191:economics / Q000209:etiology*; D018450:Disease Progression; D006801:Humans