Objective: To evaluate the relationship between serum lipid levels, retinal hard exudate, and visual acuity in patients with diabetic retinopathy.
Design: Observational data from the Early Treatment Diabetic Retinopathy Study.
Participants: Of the 3711 patients enrolled in the Early Treatment Diabetic Retinopathy Study, the first 2709 enrolled had serum lipid levels measured.
Main outcome measures: Baseline fasting serum lipid levels, best-corrected visual acuity, and assessment of retinal thickening and hard exudate from stereoscopic macular photographs.
Results: Patients with elevated total serum cholesterol levels or serum low-density lipoprotein cholesterol levels at baseline were twice as likely to have retinal hard exudates as patients with normal levels. These patients were also at higher risk of developing hard exudate during the course of the study. The risk of losing visual acuity was associated with the extent of hard exudate even after adjusting for the extent of macular edema.
Conclusions: These data demonstrate that elevated serum lipid levels are associated with an increased risk of retinal hard exudate in persons with diabetic retinopathy. Although retinal hard exudate usually accompanies diabetic macular edema, increasing amounts of exudate appear to be independently associated with an increased risk of visual impairment. Lowering elevated serum lipid levels has been shown to decrease the risk of cardiovascular morbidity. The observational data from the Early Treatment Diabetic Retinopathy Study suggest that lipid lowering may also decrease the risk of hard exudate formation and associated vision loss in patients with diabetic retinopathy. Preservation of vision may be an additional motivating factor for lowering serum lipid levels in persons with diabetic retinopathy and elevated serum lipid levels.