Severity distribution of diabetic macular edema at the time of diagnosis.

BACKGROUND: The International Clinical Diabetic Macular Edema Disease Severity Scale grades retinal thickening according to its distance from the macular center, but its definitions have not been standardized quantitatively. We undertook this study to identify the severity distribution of diabetic macular edema at the time of diagnosis. We used optical coherence tomography (OCT) in a standardized manner and identified the proportion of eyes that required immediate treatment. METHODS: We carried out an observational, prospective, cross-sectional, descriptive study. Diabetic patients with a diagnosis of clinically significant macular edema were evaluated. Severity levels according to the International Clinical Scale were operatively defined, guided by the thickening location in a 6-mm OCT fast macular map, as mild (thickening outside the 3-mm circle), moderate (thickening outside the 1-mm circle), and severe (thickening within the 1-mm circle). The proportion and 95% confidence intervals (CI) were identified for each severity level. RESULTS: We studied 118 eyes (mean ± SD: 59.9 ± 8.3 years). Seventy one eyes had nonproliferative retinopathy (60.1%), 94 eyes (79.7%) had focal macular edema, and 24 eyes (20.3%) showed diffuse edema. Edema severity was mild in 27 eyes (22.9%, 95% CI 15.3-30.5), moderate in 23 (19.5%, 95% CI 12.3-26.6) and severe in 68 (57.6% 95% CI 48.7-66.5). CONCLUSIONS: Standardization of the International Clinical Scale using OCT showed that the most common severity level of macular edema was severe; the minimum expected proportion of eyes with high risk of visual loss secondary to severe edema approached 50%. Opportune detection needs reinforcement because more than half of these eyes require immediate treatment.