Macular thickness and systemic markers for diabetes in individuals with no or mild diabetic retinopathy

Background: The relationship between diabetic risk factors and macular thickness in individuals without clinically detectable diabetic macular oedema has yet to be formally explored. The purpose of this study was to assess the correlation between macular thickness and diabetes control and duration. Methods: This was a prospective, cross-sectional study. All subjects underwent digital retinal imaging and Stratus OCT macular thickness scanning both eyes. Mean retinal thickness was determined for quadrants, rings, hemispheres, and for the central fovea (CFT), total fovea (TFT) and total macula (TMT). Results: We evaluated 92 non-diabetic controls, 92 diabetic subjects with no diabetic retinopathy (DR) and 24 subjects with mild DR at the Veteran's Hospital in Jamaica Plain, MA. In subjects with diabetes, there was a significant negative correlation between retinal thickness and diabetes duration in all macular quadrants, rings and hemispheres, and for CFT, TFT and TMT (CFT: P = 0.0025, r = -0.28; TFT: P = 0.0062, r = -0.25; TMT: P = 0.0026, r = -0.28). There was no significant relationship between retinal thickness and HbA1c level (average of last three readings), systolic or diastolic blood pressure, or triglyceride levels. Additionally, no significant differences in retinal thickness were found between controls, subjects with no DR and subjects with mild DR. Conclusions: In subjects with no or mild DR, macular and foveal thickness is significantly thinner with longer duration of disease. This may reflect neurodegenerative changes in the diabetic retina.