Abstract
Purpose:
In diabetic retinopathy screenings, exudates within 1 disc diameter (DD) of the foveola are routinely used as a surrogate marker for clinically significant macular edema (CSME). We compared central macular thickness of diabetic eyes, which in photos, had and did not have exudates within 1 DD of the foveola.
Methods:
Patients were recruited from a diabetic retinopathy screening program serving mainly minorities in Alameda County, CA. One eye from each of 200 diabetic patients with diabetes was selected: 100 cases (50 males and 50 females) had exudates within 1 DD of the foveola, and 100 gender-, age-, and ethnicity-matched control diabetics did not have exudates within 1 DD of the foveola. Central macular thickness was determined using the iVue SD-OCT (Optovue Inc, Fremont, CA). Immediately following the OCT, three overlapping fundus photographs of each eye were taken with a Canon Cr-DGi nonmydriatic camera (Tokyo, Japan). Photos were graded by two EyePACS certified graders in a blind manner. Sensitivity and specificity of retinal photos for CSME were determined using the OCT as a gold standard. A 3-way ANOVA was performed for gender, age group (<55 years vs >55 years), and case versus control.
Results:
Central macular thickness was significantly greater for eyes with exudates within 1DD of the foveola versus eyes without (261±54 vs 244±23 μm, p=0.002). Notably, central macular thickness was greater in eyes with exudates within 1 DD of the fovea compared to those without in only the males (275±54 vs 249±25 μm, p=0.003). In the females, the two groups did not differ (247±51 vs 237±19 μm, p=0.2). ANOVA analysis also showed that central macular thickness was significantly greater among the entire group of males compared to the females (262±45 vs 243±39 μm, p<0.0001). Regardless of exudates, older patients (>55 years) had significantly greater central macular thickness than younger patients (260±54 vs 245±39 μm, p=0.009). In this study, exudates within 1 DD of the foveola had a sensitivity and specificity of 96% (95% CI=90-99%) and 82% (73-88%) for CSME, respectively.
Conclusions:
This study suggests that the surrogate marker for CSME, exudates within 1 DD of the foveola, is associated with central macular thickening. This central macular thickening is significantly greater in males, but not in females. Thus, the surrogate marker for CSME may be more important in males than in females.
Keywords: 499 diabetic retinopathy •
550 imaging/image analysis: clinical •
585 macula/fovea