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Early Treatment Diabetic Retinopathy Study (ETDRS)

This study has been completed.
Information provided by:
National Eye Institute (NEI) Identifier:
First received: September 23, 1999
Last updated: September 1, 2006
Last verified: October 2003

To evaluate the effectiveness of both argon laser photocoagulation and aspirin therapy in delaying or preventing progression of early diabetic retinopathy to more severe stages of visual loss and blindness.

To help determine the best time to initiate photocoagulation treatment in diabetic retinopathy.

To monitor closely the effects of diabetes mellitus and of photocoagulation on visual function.

To produce natural history data that can be used to identify risk factors and test etiologic hypotheses in diabetic retinopathy.

Condition Intervention Phase
Diabetic Retinopathy
Drug: Aspirin
Procedure: Argon Laser Photocoagulation
Phase 3

Study Type: Interventional
Study Design: Allocation: Randomized
Primary Purpose: Treatment

Resource links provided by NLM:

Further study details as provided by National Eye Institute (NEI):

Study Start Date: December 1979
Detailed Description:

ETDRS was a multicenter, randomized clinical trial designed to evaluate argon laser photocoagulation and aspirin treatment in the management of patients with nonproliferative or early proliferative diabetic retinopathy. A total of 3,711 patients were recruited to be followed for a minimum of 4 years to provide long-term information on the risks and benefits of the treatments under study.

The eligibility criteria for the ETDRS were designed to include a broad range of macular edema severity, from a few small hard exudates within a disc diameter of the fovea with normal visual acuity to extensive cystoid spaces with a visual acuity of 20/200. All study patients had one eye randomly assigned to immediate photocoagulation and the other eye to deferral of photocoagulation until high-risk proliferative retinopathy developed. During followup, additional photocoagulation was allowed for any degree of macular edema within the eligibility range, but additional photocoagulation was required only for edema involving or threatening the center of the macula. The term "clinically significant macular edema" was coined to designate this level of severity.

The trial use of aspirin therapy was based on clinical observation and on aspirin's possible mechanisms of action. Previous observations of diabetic patients who were taking large doses of aspirin for rheumatoid arthritis showed that the prevalence of retinopathy in this group was lower than the prevalence that would be expected in the diabetic population at large. Evidence suggested that diabetic patients have altered platelet aggregation and disaggregation, which may contribute to the capillary closure seen in retinopathy. This abnormality is reversed by aspirin in vitro . However, because of aspirin's other possible mechanisms of action and its well-known side effects, such as allergic, idiosyncratic, and intolerance reactions, the use of this therapy in the ETDRS was carefully controlled and monitored.


Ages Eligible for Study:   18 Years to 70 Years   (Adult, Senior)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No
Men and women between the ages of 18 and 70 years with moderate or severe nonproliferative diabetic retinopathy or mild proliferative retinopathy in both eyes, with no previous photocoagulation treatment, and with visual acuity of 20/40 or better (20/200 or better if macular edema is present) were eligible for this study.
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Additional Information:
Publications: Identifier: NCT00000151     History of Changes
Other Study ID Numbers: NEI-53
Study First Received: September 23, 1999
Last Updated: September 1, 2006

Additional relevant MeSH terms:
Diabetic Retinopathy
Retinal Diseases
Eye Diseases
Diabetic Angiopathies
Vascular Diseases
Cardiovascular Diseases
Diabetes Complications
Diabetes Mellitus
Endocrine System Diseases
Vision Disorders
Sensation Disorders
Neurologic Manifestations
Nervous System Diseases
Signs and Symptoms processed this record on April 24, 2017