What Is Diabetic Retinopathy?

The eye is a very complicated organ — although a small organ, there are many parts of the eye that allow us to see. Some terms that will help you understand some of the information that follows are listed below.1

  • Fovea: Small depression in the retina of the eye where visual sharpness is highest; the center of the field of vision is focused in this region
  • Fundus: The part of a hollow organ that is farthest from the opening; in the eye, the part of the eyeball opposite the pupil
  • Intravitreal injection: Treatment where a medication is injected into the vitreous cavity in the middle of the eye
  • Macula: A small area at the center of the retina where light is sharply focused to produce the detailed color vision needed for tasks such as reading and driving
  • Neovascularization: Excessive growth of new blood vessels on abnormal tissue as a result of lack of oxygen
  • Proliferative diabetic retinopathy (PDR): An advanced stage of diabetic retinopathy in which new abnormal blood vessels and scar tissue form on the surface of the retina; scar tissue can pull on the retina and cause retinal detachment and loss of vision
  • Retina: Thin layer of tissue that lines the back of the eye on the inside located near the optic nerve; it receives light that the lens has focused, converts the light into neural signals, and sends these signals on to the brain for visual recognition
  • Vitreous: A gel-like substance that fills the inside of the eyeball

Diabetic retinopathy is the leading cause of acquired blindness in the U.S. in patients aged 20 to 74 years.2,3 Diabetic retinopathy is a highly specific complication of both type 1 and type 2 diabetes affecting the nerves and vessels of the eye, with the prevalence strongly correlating to both the duration of diabetes and level of glycemic (glucose) control.4 In the U.S., diabetic retinopathy affects approximately 86% of patients with type 1 diabetes mellitus (T1DM) and 40% of patients with type 2 diabetes mellitus (T2DM).5-7 According to the Centers for Disease Control and Prevention (CDC), nearly 22% of the 4.1 million Americans with diabetic retinopathy are at risk for vision-threatening complications.5

Vision loss due to diabetic retinopathy results from several mechanisms highlighted in the following Figure.4

  • Central vision may be impaired by macular edema (swelling) as the result of increased vascular permeability (vessel leakage) and/or capillary nonperfusion
  • New blood vessels of proliferative diabetic retinopathy and contraction of the accompanying fibrous tissue can distort the retina and lead to retinal detachment producing severe and often irreversible vision loss
  • New blood vessels may bleed
  • Vascular changes can be accompanied by damage to retinal neurons
Figure: Illustration Comparing Normal Retina (top) to Features of Diabetic Retinopathy (bottom).8

Macular edema develops when excess fluid accumulates within the macular retina and can occur at any stage of diabetic retinopathy. Diabetic macular edema is a general term defined as retinal thickening within 2 disc diameters of the foveal center and is one of the most common causes of visual loss in patients with diabetes mellitus;11 and the severity may range from mild and asymptomatic to profound loss of vision.


  1. American Society of Retina Specialists (ASRS). Diabetic retinopathy. https://www.asrs.org/patients/retinal-diseases/3/diabetic-retinopathy. Accessed November 26, 2019.
  2. Farley TM, Mandava N, Prall FR, Carsky C. Accuracy of primary care clinicians in screening for diabetic retinopathy using single-image retinal photography. Ann Fam Med. 2008;6:428-434.
  3. Varma R. Diabetic retinopathy: challenges and future directions Am J Ophthalmol. 2006;141:539-541.
  4. Solomon SD, Chew E, Duh EJ, et al [2017 ADA Position Statement]. Diabetic retinopathy: A position statement by the American Diabetes Association. Diabetes Care. 2017;40(3):412–418.
  5. CDC Vision Health Initiative. Diabetic retinopathy. https://www.cdc.gov/visionhealth/publications/diabetic_retinopathy.htm.
    Accessed February 18, 2019.
  6. Opere CA, O’Brien KK, Shea JL. Understanding diabetic retinopathy U.S. Pharm. 2011;36:46-52.
  7. Cheung N, Mitchell P, Wong T. Diabetic retinopathy 2010;376:124-136. 2010;376:124-136.
  8. Eshaq RS, Aldalati AMZ, Alexander JS, Harris NR. Diabetic retinopathy: Breaking the barrier. Pathophysiology. 2017;24:229–241.
  9. Rotsos TG, Moschos MM. Cystoid macular edema. Clin Ophthalmol. 2008;2:919-930.
  10. Garg S, Davis RM. Diabetic retinopathy screening update. Clin Diabetes. 2009;27:140-145.
  11. Javey G, Schwartz SG, Flynn Jr HW. Emerging pharmacotherapies for diabetic macular edema. Exp Diabetes Res.
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Patient & Caregiver Educational Resources

The RELIEF Patient Toolkit is a resource center for patients who have been diagnosed with or who are interested in learning about diabetic retinopathy (DR). Choose from the options below to learn more.

This activity is provided by Med Learning Group. This activity is co-provided by Ultimate Medical Academy/CCM.
This activity is supported by an educational grant from Regeneron Pharmaceuticals, Inc.

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Scientific Council

Neil M. Bressler, MD

James P. Gills Professor of Ophthalmology
Professor of Ophthalmology, Johns Hopkins University School of Medicine
Wilmer Eye Institute, Johns Hopkins Medicine
Baltimore, MD

A. Paul Chous, MA, OD, FAAO

Specializing in Diabetes Eye Care & Education, Chous Eye Care Associates
Adjunct Professor of Optometry, Western University of Health Sciences
AOA Representative, National Diabetes Education Program
Tacoma, WA

Steven Ferrucci, OD, FAAO

Chief of Optometry, Sepulveda VA Medical Center
Professor, Southern California College of Optometry at Marshall B. Ketchum University
Sepulveda, CA

Julia A. Haller, MD

Wills Eye Hospital
Philadelphia, PA

Allen C. Ho, MD, FACS

Director, Retina Research
Wills Eye Hospital
Professor and Chair of the Department of Ophthalmology
Thomas Jefferson University Hospitals
Philadelphia, PA

Charles C. Wykoff, MD, PhD

Director of Research, Retina Consultants of Houston
Associate Professor of Clinical Ophthalmology
Blanton Eye Institute & Houston Methodist Hospital
Houston, TX