A severity scale for diabetic macular edema developed from ETDRS data.

ment. 2 The ETDRS also reported several factors associated with baseline VA, the most notable of which were area of RT, degree of RT at the macular center, and severity of fluorescein leakage within 1 disc diameter (DD) of the macular center. In a subset of 741 eyes with mild to moderate nonproliferative retinopathy and macular edema questionably or definitely involving the macular center, VA score at baseline was 70 letters (corresponding to 20/40 or better) in 92.5% of eyes in which the area of RT within 1 DD of center was 0.5 disc area (DA) versus 43.4% of eyes in which this area was 2.0 DA. Corresponding proportions for eyes in the lowest and highest categories of fluorescein leakage were 85.2% and 50.0% and for degree of RT at the macular center, they were 91.3% and 63.4%. 3 The objectives of this report are to describe the development of a more detailed scale to categorize the severity of DME and to use the scale to assess the relationship between the duration of severe DME and VA. The scale is based on associations between baseline gradings of features characteristic of DME in stereoscopic color fundus photographs and best corrected baseline VA. 4,5