Therapeutic effect of lutein supplement on non-proliferative diabetic retinopathy: A retrospective study, This study retrospectively evaluated the effect of lutein supplement (LS) on patients with non-proliferative diabetic retinopathy (NPDR). A total of 72 patients with NPDR were included in this study. All patients received Zeaxanthin during the study period. In addition, 36 patients also received LS and were assigned to the treatment group, while the other 36 patients did not receive LS and were assigned to the control group. All patients were treated for a total of 4 months. The endpoints included visual acuity (VA), contrast sensitivity (CS), and glare sensitivity (GS). In addition, any adverse events were also assessed. All endpoints were measured before and after 4-month treatment. Before treatment, there were no significant differences in VA (P = .75), CS (P = .71), and GS (P = .73) between two groups. After 4-month treatment, there were still no significant differences in all endpoints of VA (P = .66), CS (P = .58), and GS (P = .61) between two groups. No adverse events were recorded in either group. The results of this retrospective study showed that LS may not benefit for patients with NPDR after 4-month treatment. More high quality randomized controlled trials should still be needed to warrant the results of this study.