• Thickening measured by optical coherence tomography in 3 zones: central subfield (when field 1 was thickened), inner ring (when any of fields 2, 3, 4 or 5 was thickened), and inner ring or outer ring (when any of fields 6, 7, 8, or 9 was thickened) [ Time Frame: at the diagnosis moment ] [ Designated as safety issue: Yes ]
  

• Severity level: adaptation of International clinical diabetic macular edema severity scale to fields of the OCT; mild if thickening exclusively involved outer-ring, moderate if was in inner-ring without involvement field 1, and severe if was in field 1 [ Time Frame: at the diagnosis moment ] [ Designated as safety issue: Yes ]
  

The international severity scale grades macular edema as mild, moderate or severe, according to the distance of the thickening from the center of the fovea; However, this scale does not define the distances which fulfill the criteria of "distant from" or "approaching" the center of the macula; a quantitative and reproducible tool, such as optical coherence tomography (OCT), could be more accurate to grade severity, by localizing thickening in a standardized way. As far as we know, distribution of clinically significant macular edema at the moment of diagnosis, according to the international scale has not been described. A study was conducted to identify the rate of eyes that had severe macular edema at the moment of diagnosis, whose risk of visual loss could be higher and required immediate treatment.