The Early Treatment Diabetic Retinopathy Study (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 followed for a minimum of four years to provide long-term information on the risks and benefits of the treatment under study. All study patients had one eye randomly assigned to immediate photocoagulation and the other eye to deferral of photocoagulation until high-risk proliferative diabetic retinopathy (PDR) developed.
Aspirin use was found not to affect the progression of retinopathy to the high-risk proliferative stage in eyes assigned to deferral of photocoagulation. However, aspirin did not increase the risk of vitreous hemorrhage, did not affect vision, and was associated with a decreased risk of cardiovascular disease. The investigators therefore concluded that for patients with mild to severe nonproliferative diabetic retinopathy (NPDR) or early PDR, aspirin likely has no important beneficial effect on the progression of retinopathy. However, the study also showed no clinically important harmful effects for diabetic patients with retinopathy and therefore no ocular contraindications to aspirin use when required for cardiovascular disease or other medical indications.
With regard to focal treatment for macular edema, the ETDRS demonstrated that photocoagulation reduced the risk of moderate vision loss, especially for those eyes with macular edema that involved or threatened the center of the macula. There was an increase of moderate visual gain in those eyes that received focal treatment as well as a decrease in the amount of retinal thickening.
With regard to scatter treatment, the study demonstrated a statistically significant reduction in severe visual loss for those eyes with early treatment, especially for those patients with type 2 (non-insulin-dependent) diabetes. However, the reduction was small and the risk was low in the deferral group.
Before current treatments, the prognosis for patients with PDR was blindness within five years for more than 50% of patients. Rates of blindness in ETDRS patients following the development of PDR were remarkably lower: Legal blindness was reduced to less than 5% in five years for patients with PDR, and severe vision loss was reduced to 1%.
Selected Publications
Fong DS, Ferris FL, Davis MD, et al. ETDRS Research Group: Causes of severe visual loss in the Early Treatment Diabetic Retinopathy Study. ETDRS Report No. 24. Am J Ophthalmol 1999;127:137-141.
Davis MD, Fisher MR, Gangnon RE, et al. Risk factors for high-risk proliferative diabetic retinopathy and severe visual loss: Early Treatment Diabetic Retinopathy Study Report #18. Inv Ophthalmol Vis Sci 1998;39:233-252.
Chew EY, Klein ML, Murphy RP, et al. Early Treatment Diabetic Retinopathy Study Research Group: Effects of aspirin on preretinal hemorrhage in patients with diabetes mellitus. ETDRS Report Number 20. Arch Ophthalmol 1995;113:52-55.
Early Treatment Diabetic Retinopathy Study Research Group. Focal photocoagulation treatment of diabetic macular edema. ETDRS Report Number 19. Arch Ophthalmol 1995;113:1144-1155.
Early Treatment Diabetic Retinopathy Study Research Group. Early photocoagulation for diabetic retinopathy: ETDRS Report Number 9. Ophthalmology 1991;98:766-785.
Ferris FL III, Davis MD, Aiello LM. Treatment of diabetic retinopathy. N Engl J Med 1999;341:667-678.
Click on the highlighted citations for summaries of studies
The Wisconsin Epidemiologic Study
Diabetes Control and Complications Trial Research Group
The Diabetic Retinopathy Study Research Group
Diabetic Retinopathy Vitrectomy Study Research Group
UK Prospective Diabetes Study
This web resource is made possible through an unrestricted educational grant from Eli Lilly and Company.
|
