Evaluation of Therapeutic Effect and Mechanism of Traditional Chinese Medicine on Non-Proliferative Diabetic Retinopathy

Abstract Objective: To review the therapeutic effect and mechanism of traditional Chinese medicine (TCM) on non-proliferative diabetic retinopathy (NPDR).Methods: Randomized controlled studies (RCTs) on NPDR treatment with TCM was conducted by searching China National Knowledge Internet, Wanfang Database, Chinese Biomedical Literature Database, PubMed, EMBASE, Cochrane database. The search date was up to December 24, 2019. At the same time, the mechanism of NPDR with TCM include studies was conducted by searching China National Knowledge Internet, Wanfang Database, PubMed.Results: 3208 related literatures were retrieved and 36 RCTs were included, including 3691 patients. The overall curative effect was significant [n = 4028, RR 1.20 (1.16, 1.25), P < 0.00001, I2 = 35%] with Qiming granule, Compound Xueshuantong capsule, no matter treated with TCM alone or combined with chemical drugs, it could show significant advantages. At the same time, TCM can effectively improve the fundus, and vision, reduce macular thickness, and microangioma of NPDR patients. TCM can reduce the generation of vascular endothelial growth factor and improve the blood retinal barrier through polyol pathway, oxidative stress pathway, etc.Conclusion: Our study shows that TCM has a significant effect on NPDR, and can significantly improve vision, reduce microangioma and macular thickness, and is safe. TCM mainly protects retinal neurons and blood retinal barrier through polyol pathway, which suggests that TCM can prevent macular edema and neovascularization in NPDR patients. However, in consideration of the quality of literature, the results of this study should be carefully considered.