Macular Edema in Diabetes
- Author: Emmanouil Mavrikakis, MD, PhD; Chief Editor: Hampton Roy Sr, MD more...
Background
The Early Treatment Diabetic Retinopathy Study (ETDRS) set the guidelines for the treatment of diabetic macular edema (DME). Since that time, the standard of treatment for diabetic macular edema has been glycemic control as demonstrated by the Diabetes Control and Complications Trial (DCCT), optimal blood pressure control as demonstrated by the United Kingdom Prospective Diabetes Study (UKPDS), and macular focal/grid laser photocoagulation.
In ETDRS, laser photocoagulation reduced the risk of moderate visual loss from diabetic macular edema by 50% (from 24% to 12% 3 years after initiation of treatment).[1] Nevertheless, some patients suffer permanent visual loss even after intensive treatment.
Over the past few years, research has started to focus on the use of anti-vascular endothelial growth factor (VEGF) therapy to treat DME. As new and promising treatment options emerge, these treatments will need to be reevaluated.
It is imperative for patients with diabetes to understand that a healthy lifestyle and compliance with medical care can greatly reduce the development and progression of complications of their disease, in the eyes as well as other organs.
For patient education information, see the Diabetes Center, as well as Diabetic Eye Disease.
For further clinical information, see the Medscape Reference articles Diabetes Mellitus, Type 1, Diabetes Mellitus, Type 2, and Diabetic Retinopathy.
Pathophysiology
Diabetic macular edema results from retinal microvascular changes. Thickening of the basement membrane and reduction in the number of pericytes are believed to lead to increased permeability and incompetence of the retinal vasculature. This compromise of the blood-retinal barrier leads to the leakage of plasma constituents into the surrounding retina, with subsequent retinal edema.[2] Hypoxia produced by this mechanism can also stimulate the production of vascular endothelial growth factor (VEGF). There is evidence that VEGF is up-regulated in diabetic macular edema and proliferative diabetic retinopathy.[3]
A study suggests that the pathogenesis of diabetic macular edema is not only related to VEGF dependency but also to other inflammatory and angiogenic cytokine levels that can be suppressed by corticosteroids.[4]
Epidemiology
Diabetes is the leading cause of new blindness in the United States, and clinically significant macular edema (CSME) contributes greatly to this vision loss. In the absence of ophthalmologic treatment, persons with diabetes have a 25-30% risk of moderate vision loss. With treatment, the risk drops by 50%. According to 2007 data, 23.6 million people in the United States have diabetes, but only 17.9 million have been diagnosed.[5] . About 50% of those with diagnosed diabetes do not receive appropriate eye care. The World Health Organization estimates that worldwide, more than 150 million people have diabetes.
Although diabetes is more common in Hispanics, African Americans, and Native Americans than in whites, no data describe a greater risk of developing macular edema among diabetic patients of any one racial group. Likewise, no data describe a difference in risk of diabetic macular edema between the sexes.
Diabetic retinopathy, not specifically diabetic macular edema, generally occurs in persons older than 40 years. It rarely occurs before puberty.
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