Quantitative measurement of hard exudates in patients with diabetes and their associations with serum lipid levels

Abstract

Purpose. To describe a reproducible method of quantifying macular hard exudates (HEs) in diabetic maculopathy and determine the associations of HEs with systemic risk factors. Methods. Patients with diabetes were recruited from a tertiary eye hospital in Melbourne, Australia. Total macular area covered by HEs (total HE area) and the distance from the foveal center to the nearest HE were measured in a semi-automated manner. Associations between HE parameters and diabetic complication risk factors were examined using multiple linear regression models. Results. Of 593 participants (mean age 60.5-years old), 97 (16.4%) had HEs in at least one eye, due to diabetic maculopathy. The intraclass correlation coefficients (ICC) for inter and intra-observer agreements were 0.982 and 0.999, respectively. Total HE area was positively associated with qualitative HE severity scale determined by photographic graders. The median of total HE area was 0.089 mm2 (interquartile range, 0.027-0.246). The median distance between foveal center and the nearest HE was 791.1 μm (431.9-1385.4). After adjusting for age, sex, duration of diabetes, glycated hemoglobin, mean arterial pressure, diabetic retinopathy level, and use of lipid-lowering medication, low density lipoprotein (LDL) cholesterol (P = 0.009), and triglyceride levels (P = 0.036) were positively associated with total HE area. Higher triglyceride levels were associated with central involvement (P = 0.023). Conclusions. Quantitative measurement of HEs in patients with diabetes is associated with lipid levels, and higher triglyceride levels are associated with a higher risk of central involvement. Quantitative information may be useful to monitor HE progression or treatment response in persons with diabetic maculopathy. © 2013 The Association for Research in Vision and Ophthalmology, Inc.