Utility of Hard Exudates for the Screening of Macular Edema

Abstract

Purpose To determine whether hard exudates (HE) 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 143 adults diagnosed with diabetes mellitus were imaged using a non-mydriatic digital fundus camera at the Alameda County Medical Center in Oakland, CA. Non-stereo 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 exam on a separate visit. CSME 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 hard exudates within one disc diameter of the foveola in non-stereo digital images used as a surrogate for the detection of CSME diagnosed by live fundus examination were calculated. Results The mean age of 103 patients included in the analysis was 56±17years. CSME was diagnosed in 15.5% of eyes during the dilated exam. For the right eyes, the sensitivity of hard exudates within one disc diameter from the foveola as a surrogate for detecting CSME was 93.8% for each of the graders; the specificity was 88.5% and 85.1%. For the left eyes, the sensitivity was 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 disk diameter of the center of the macula in non-stereo digital images for CSME detection in a screening setting.

Clinical Application of Multicolor Imaging Technology

“…These features were imaged more clearly on the multicolor image than the CFP. Diabetic macular edema (DME) as a complication of diabetic retinopathy is difficult to detect on CFP during screening in the absence of hard exudation [25,26]. Stereoscopic photographs improve the detection of retinal thickening; however, they cannot be performed in an undilated pupil.…”

Screening for macular disorders: the optometrist's perspective

“…Hard exudates are associated with a reduction in VA by the ETDRS. 32 Hard exudates are used as a surrogate marker for DME when increased retinal thickness cannot be determined, 14 although hard exudates may not yet be visible if there is no resorption of fluid. Grading is discussed in more detail herein.…”

“…However, in some cases the resources are present, but the patients do not perceive the risks of sight-threatening vision loss. 12 Successful models range from but are not limited to a permanent screening and patient-referral network 13,14 (Figure 6) to an annual targeted campaign by Volunteer Optometric Services to Humanity (VOSH) with known referral for patients ( Figure 7) to a specific campaign at a new location.…”

Telemedicine and Diabetic Retinopathy: Review of Published Screening Programs

“…If an outside grader was used, the grader had to undergo EyePACS certification [15]. The system was initially piloted in 2006 on 3,500 patients [16], and as of 2010, EyePACS has facilitated over 53,000 screening encounters for DR in California [17]. However, of the 15% of patients referred for follow-up care through EyePACS screening, only 30% returned to their eye care provider for follow-up [17].…”

“…They used the presence of hard exudates within one disc diameter of the fovea as a surrogate marker for CSDME, which had been shown to have a good sensitivity for CSDME in non-stereoscopic imaging [16]. In a study looking at the diagnosis of CSDME in 143 patients using the EyePACS system compared to in-person examination by an optometrist, the program was found to have sensitivity between 75% and 93.8% and specificity between 85.1% and 88.5% between multiple image graders [17]. …”