Diabetic retinopathy: Classification and clinical features
- Claire E Fraser, MD, PhD
Claire E Fraser, MD, PhD
- Assistant Professor, Vitreoretinal Surgery
- University of Kentucky
- Donald J D'Amico, MD
Donald J D'Amico, MD
- Chairman of Ophthalmology
- Weill Cornell Medical College
- Section Editors
- David M Nathan, MD
David M Nathan, MD
- Editor-in-Chief — Endocrinology
- Section Editor — Diabetes Mellitus
- Professor of Medicine
- Harvard Medical School
- Jonathan Trobe, MD
Jonathan Trobe, MD
- Section Editor — Ophthalmology
- Professor of Ophthalmology and Visual Sciences
- Professor of Neurology
- University of Michigan Kellogg Eye Center
Diabetic retinopathy (DR) is one of the most important causes of visual loss worldwide and is the principal cause of impaired vision in patients between 25 and 74 years of age. Visual loss from DR may be secondary to macular edema (ME; retinal thickening and edema involving the macula), hemorrhage from new vessels, retinal detachment, or neovascular glaucoma.
The vast majority of patients who develop DR have no symptoms until the very late stages. Because the rate of progression may be rapid and therapy can be beneficial for both symptom amelioration and reduction in the rate of disease progression, it is important to screen patients with diabetes regularly for the development of retinal disease.
The classification, clinical features, and natural history of DR will be reviewed here. The pathogenesis, screening, and treatment of DR are discussed elsewhere (see "Diabetic retinopathy: Pathogenesis" and "Diabetic retinopathy: Screening" and "Diabetic retinopathy: Prevention and treatment"). Cataracts associated with diabetes are also a major cause of visual impairment, especially in type 2 diabetes. Cataracts are reviewed separately. (See "Cataract in adults".)
DR is divided into two major forms: nonproliferative and proliferative, named for the absence or presence of abnormal new blood vessels emanating from the retina. DR can be further classified by severity (table 1 and picture 1 and picture 2). These stratifications have been useful for analysis of treatment efficacy in the literature and general indicators for treatment strategies. However, each patient with DR has a unique combination of findings, symptoms, and rate of progression, which necessarily requires an individualized approach to treatment in the effort to preserve vision.
Nonproliferative retinopathy — Nonproliferative DR (NPDR) consists of a variable display of nerve-fiber layer infarcts (cotton wool spots), intraretinal hemorrhages, and hard exudates, and microvascular abnormalities (including microaneurysms, occluded vessels, and dilated or tortuous vessels) primarily in the macula and posterior retina (picture 3). Visual loss in NPDR is primarily through the development of macular edema (ME). (See 'Macular edema' below.)
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- Nonproliferative retinopathy
- Proliferative retinopathy
- Macular edema
- CLINICAL MANIFESTATIONS
- Ophthalmologic features
- - Neovascularization
- - Retinal thickening and edema
- NATURAL HISTORY
- Transient worsening with intensive insulin therapy
- Worsening during pregnancy
- Morbidity and mortality
- SUMMARY AND RECOMMENDATIONS