Evaluating How the Treatments in the Action to Control Cardiovascular Risk in Diabetes (ACCORD) Study Affect Diabetic Retinopathy (The ACCORD Eye Study)

• Progression of Diabetic Retinopathy of at Least 3 Stages on the Early Treatment Diabetic Retinopathy Study (ETDRS) Scale, or Development of Proliferative Diabetic Retinopathy Necessitating Photocoagulation Therapy or Vitrectomy [ Time Frame: Measured at Year 4 ]
  Diabetic retinopathy status was defined according to the eye with the highest level on the ETDRS Final Severity Scale for Persons, as follows: no diabetic retinopathy, a level of less than 20; mild diabetic retinopathy, a level of 20; moderate nonproliferative diabetic retinopathy (NPDR), a level above 20 but less than 53; severe diabetic retinopathy, a level of 53 but less than 60; and proliferative diabetic retinopathy (PDR), a level of 60 or higher.
  
  

• Loss of Visual Acuity, Cataract Extraction, or Development or Progression of Macular Edema [ Time Frame: Measured at Year 4 ]
  

DR is the most common diabetic eye disease and is the leading cause of blindness in adults in the United States. It is caused by damage to the blood vessels of the retina, which is the light-sensitive outer layer of the eye. Retinal blood vessels are often affected by the high blood sugar levels associated with diabetes. Older people have an increased risk of developing DR; however, DR is likely to occur earlier and be more severe in anyone who has poorly controlled diabetes. Almost everyone who has had diabetes for more than 30 years will eventually show signs of DR. Symptoms of DR include poor night vision, seeing spots in front of the eyes, blurred vision, and blindness. The ACCORD study is a study that is examining the effects of different treatments on cardiovascular disease in people with diabetes. Participants in the ACCORD study will receive one of eight different combinations of treatment, including blood sugar control, blood pressure control, and cholesterol-controlling medication. This study will enroll participants in the ACCORD study and will examine the effects of the study treatments on DR. The results from this study may be used to develop new treatments to help prevent diabetes-related blindness.

Study visits will occur at baseline and Year 4. At each study visit, participants will have an eye exam and specialized fundus photographs taken of the back of the eye and retina.