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Key Features

Essentials of Diagnosis

  • Present in ∼33% of all diagnosed diabetic patients

  • Present in ∼20% of type 2 diabetic patients at time of diagnosis of diabetes

  • By 20 years after diagnosis of diabetes, 99% of type 1 diabetic patients and 60% of type 2 diabetic patients will have diabetic retinopathy

  • Nonproliferative diabetic retinopathy

    • Can be mild, moderate, or severe

    • Microvascular changes are limited to the retina

  • Proliferative (new blood vessel growth) diabetic retinopathy

    • Blood vessels grow on the retina, optic nerve, or iris

  • Diabetic macular edema

    • Central retinal swelling

    • Can occur with any severity level of diabetic retinopathy

    • Reduces visual acuity if center involved

General Considerations

  • Present in about one-third of patients in whom diabetes has been diagnosed; about one-third of those have sight-threatening disease

  • Prevalence and severity increases with longer duration and poorer control of diabetes

  • In type 1 diabetes, retinopathy is not detectable for the first 5 years after diagnosis

  • In type 2 diabetes, about 20% of patients have retinopathy at diagnosis likely because they had diabetes for an extensive period of time before diagnosis

  • Macular involvement is the most common cause of legal blindness in type 2 diabetes

  • There are two main categories of diabetic retinopathy

    • Nonproliferative

      • Subclassified as mild, moderate, or severe

      • Diabetic macular edema can occur at any stage

      • "Background" retinopathy represents the earliest stage of retinal involvement by diabetes

    • Proliferative

      • Less common than nonproliferative but causes more severe visual loss

      • Involves the growth of new capillaries and fibrous tissue on the surface of the retina, extending into the vitreous chamber


  • In the United States, it affects about 4 million people; it is the leading cause of new blindness among adults aged 20–65 years; and the number of affected individuals aged 65 years or older is increasing

  • Worldwide, there are approximately 93 million people with diabetic retinopathy, including 28 million with vision-threatening disease

Clinical Findings

  • Nonproliferative retinopathy

    • Manifests as microaneurysms, retinal hemorrhages, venous beading, retinal edema, and hard exudates

    • In mild disease, retinal abnormalities are mild without visual loss

    • Reduction of vision

      • Most commonly due to diabetic macular edema, which may be focal or diffuse

      • Can also be due to macular ischemia

      • Interference with visual acuity in clinically significant macular edema (process of retinal capillaries leaking proteins, lipids, or red cells in macula)

    • Severe disease is defined as having any one of the following:

      • Severe intraretinal hemorrhages and microaneurysms in four quadrants

      • Venous beading in two or more quadrants

      • Intraretinal microvascular abnormalities in at least one quadrant

  • Proliferative retinopathy

    • Characterized by neovascularization, arising from either the optic disk or the major vascular arcades

    • A preproliferative phase often occurs in which arteriolar ischemia is manifested as cotton-wool spots (small infarcted areas ...

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