Abstract
Purpose: :
Macular pigments (MP) consist of two dietary carotenoids (Lutein and Zeaxanthin) that act as antioxidant and optical filter in the human retina. There is strong evidence supporting their protective role in some retinal diseases, such as age related macular degeneration. Diabetic retinopathy (DR) is a major cause of blindness in the occidental world, and hyperglycemia and oxidative stress are important factors associated with its development. We investigated differences in MP optical density (MPOD) values between diabetic and non-diabetic patients using dual wavelength autofluorescence imaging.
Methods: :
A prospective study was carried out including a total of 32 subjects (non-diabetic and type 2 diabetic) divided into 3 groups: control (10 eyes), diabetic without retinopathy (13 eyes) and diabetic with mild retinopathy (10 eyes). Exclusion criteria were any other ocular disease (including diabetic macular edema) or best corrected visual acuity < 20/40. MPOD values were measured using a modified confocal scanning laser ophthalmoscope (HRA, Heidelberg Engineering Heidelberg, Germany) and then they were compared between groups (kruskal-Wallis test). If both eyes were eligible, one was randomly selected. Blood was drawn for laboratory analysis of serum lipids and HbA1C levels, which were correlated with MPOD levels (regression analysis) in all groups.
Results: :
Mean age in each group was 56.6 ± 9.5, 59.5 ± 11.8, and 65.4 ± 9.2 years, respectively (p=0.162). MPOD levels averaged in a 2° diameter circle around the fovea were significant different between diabetic patients with (0.13 ±0.07 DU), without retinopathy (0.22 ± 0.08DU) and controls (0.30 ±0.07DU; p<0.05). MPOD levels measured at 0.5° eccentricity were significant different between controls (0.52 ± 0.12DU) and diabetic patients (p<0.02), but not between diabetic patients with (0.23 ±0.11DU) and without retinopathy (0.33 ± 0.16DU; p=0.18). A significant negative correlation was found between triglycerides levels and MPOD values measured at both eccentricities in non-diabetic patients (r2=0.52 and 0.46, p<0.03). No significant correlation was detected between values of MPOD and HbA1C.
Conclusions: :
Type 2 diabetic patients with and without DR were found to have significantly reduced MPOD levels compared to controls. In addition, lower MPOD values correlated significantly with higher triglycerides levels in non-diabetic patients.
Keywords: macular pigment • diabetic retinopathy • imaging/image analysis: clinical