Role of Steroids in the Treatment of Diabetic Macular Edema

Abstract

Macular edema is a major cause of significant visual impairments and is seen in several eye diseases, including diabetic retinopathy, 1 uveitis, 2 and retinal vein occlusion. 3 Diabetic macular edema (DME) remains the predominant cause of vision impairment in people with diabetes. 1 In the Wisconsin Epidemiological Study of Diabetic Retinopathy, DME was also found to develop in 20.1% of people with type I diabetes and 25.4% of people with insulin-dependent type II diabetes over a 10 year period. 4 ' Pathophysiology of DME The pathophysiology of DME is still not completely understood but is thought to be multifactorial. Vascular cell degeneration/death, breakdown of blood retinal barrier, localized ischemia, and inflammation are all thought to contribute to retinal vascular abnormalities and leak, leading eventually to exudative edema in advanced cases. 5 Histologic studies of retinas from diabetic rodents reveal diabetesinduced degenerative changes including pericyte apoptosis and acellular capillary formation that are associated with microvascular leak. 6 In addition, several histologic features of inflammation are also evident in diabetic retinopathy including leukostasis, platelet aggregation, and the formation of micro thrombi in the microvasculature. 7 Leukostasis can result in disruption of tight junctions and the breakdown of