Macular and Foveal Thickness as Measured by OCT in Diabetic and Non-Diabetic Latinos: The Los Angeles Latino Eye Study (LALES)

Abstract

Purpose:: We hypothesized that diabetic persons may have increased macular thickness compared to nondiabetics even in the absence of macular edema and that a different normative database may be required for diabetics. The purpose of this study was to determine whether this is the case in a subset of Latinos who underwent optical coherence tomography (OCT) as part of the Los Angeles Latino Eye Study (LALES).

Methods:: The LALES is a population-based prevalence study of eye disease among Latinos aged 40 years and older. Participants underwent a standardized interview and detailed eye examination including dilated stereophotography and OCT measurements. Presence of diabetes was defined by self-reported history of diabetes, and/or Hemoglobin A1c greater than 7.0% and/or random glucose greater than 200mg%. The diagnosis of macular oedema was made from photographic grading by masked trained graders. Fast macular thickness scans were taken using the STRATUS OCT^TM Carl Zeiss Meditec. T-tests were performed to compare the difference in macular thickness between diabetics and nondiabetics and the GLM procedure to examine the mean difference after adjusting for age and gender. The average values of both eyes were used in the analyses.

Results:: Gradable optical coherence scans were available in 842 nondiabetics and in 188 diabetics. The mean age of the participants was 53 years (SD + 9.8) and 59% were female. Diabetics were older than nondiabetics (diabetics: 57 + 10.4 years; nondiabetics: 52 + 9.4 years, P=<0.0001). There was no difference in the proportion of males and females in both groups. The mean foveal retinal thickness was 187.5µm in diabetics and 181.0µm in nondiabetics (P=0.02). The mean macular thickness was 210.2µm in diabetics and 204.8µm in nondiabetics (P=0.02). There was no difference in mean macular volume between the 2 groups, but the mean central foveal volume was 0.17cubic microns vs. 0.16 in diabetics vs. nondiabetics (P=0.02). After age-sex adjustment, the differences remained significant, all P<0.02). Macular oedema was present in 18 participants, including 15 diabetics and 3 nondiabetics. When the data were re-analyzed after exclusion of these participants with macula edema, no statistically significant differences in any macular thickness measurements remained.

Conclusions:: There was no difference in mean macular thickness and foveal thickness in diabetics compared to nondiabetics without macular edema.This study supports that a separate normative database for diabetics is not required.

Keywords: macula/fovea • diabetic retinopathy • clinical (human) or epidemiologic studies: prevalence/incidence