Association of macular pigment optical density with early stage of non-proliferative diabetic retinopathy in Chinese patients with type 2 diabetes mellitus.

Aim: To detect the association between macular pigment optical density (MPOD), which reflects the antioxidant ability of retina, and diabetic retinopathy (DR) and to investigate the correlated factors of MPOD.

Methods: Totally 435 subjects of urban Chinese were recruited to the study and divided into 3 groups: non-diabetes mellitus controls (NDM), diabetic patients without retinopathy (DWR), and patients with early stage of non-proliferative diabetic retinopathy (DR). Demographic and lifestyle characteristics were ascertained by questionnaire. A food-frequency questionnaire, general physical and ophthalmic examinations were completed for all participants. MPOD was measured by heterochromatic flicker photometry. Foveal thickness was measured by optical coherence tomography. The difference of MPOD among 3 groups was analyzed by analysis of covariance. The correlation analyses of MPOD with the candidate influence factors were assessed using the generalized estimating equations (GEE) model.

Results: Of the 435 participants, 34 could not perform the MPOD measurements. Final analysis included 401 subjects, including 48 were in DR group, 134 in DWR group, and 219 in NDM group. MPOD was not significantly different among DR (0.49±0.21), DWR (0.45±0.21), and NDM (0.49±0.17) groups (=0.24) after adjustment for fasting plasma glycemia, central foveal thickness, green vegetables, Chinese wolfberry, carotene and vitamin E. For all the 401 participants included, MPOD was positively associated with central foveal thickness (E=0.0007, =0.001), Chinese wolfberry (E=0.0345, =0.01), and green vegetables (E=0.0596, <0.001) intake.

Conclusion: The data suggest that MPOD level is not statistically significantly influenced by the onset of diabetes or early stage of DR in the studied population. MPOD level is positively associated with thicker central foveal thickness and higher intake of foods containing carotenoids.