Utility of hard exudates for the screening of macular edema

Abstract

Purpose: The purpose of this study was to determine whether hard exudates (HEs) within one disc diameter of the foveola is an acceptable criterion for the referral of diabetic patients suspected of clinically significant macular edema (CSME) in a screening setting.

Methods: One hundred forty-three adults diagnosed as having diabetes mellitus were imaged using a nonmydriatic digital fundus camera at the Alameda County Medical Center in Oakland, CA. Nonstereo fundus images were graded independently for the presence of HE near the center of the macula by two graders according to the EyePACS grading protocol. The patients also received a dilated fundus examination on a separate visit. Clinically significant macular edema was determined during the dilated fundus examination using the criteria set forth by the Early Treatment Diabetic Retinopathy Study. Subsequently, the sensitivity and specificity of HEs within one disc diameter of the foveola in nonstereo digital images used as a surrogate for the detection of CSME diagnosed by live fundus examination were calculated.

Results: The mean (±SD) age of 103 patients included in the analysis was 56 ± 17 years. Clinically significant macular edema was diagnosed in 15.5% of eyes during the dilated examination. For the right eyes, the sensitivity of HEs within one disc diameter from the foveola as a surrogate for detecting CSME was 93.8% for each of the graders; the specificity values were 88.5 and 85.1%. For the left eyes, the sensitivity values were 93.8 and 75% for each of the two graders, respectively; the specificity was 87.4% for both graders.

Conclusions: This study supports the use of HE within a disc diameter of the center of the macula in nonstereo digital images for CSME detection in a screening setting.

Figure 1

Images obtained according to the EyePACS imaging protocol. (A) normal retina: left primary field OD-temporal retina and optic nerve, center) field centered on optic nerve OD, right) optic nerve and nasal retina OD. (B) and (C) would each yield referrals for retinal edema because of hard exudates within 1 disc diameter of foveola. (B) circinate ring of hard exudates involving macula OS,(C) small hard exudates within1 disc diameter of foveola.w

Figure 2

Ethnicity of patient group.