This trial is planned to collect relevant clinical data to evaluate the prevention efficacy and safety of Tangningtongluo tablets on the non-proliferation period of diabetic retinopathy.

After being informed about the study and potential risks,all patients giving written informed consent will undergo a 1-week screening period to eligibility for study entry.At week 0,patients who meet the eligibility requirements will be randomized into two groups(experimental group and control group)in a 1:1 ratio to Tangningtongluo tablets(4 tablets,tid,po.) or Calcium dobesilate capsules(1 capsule,tid,po.).

Inclusion Criteria:

• 1. Patients with the diagnosis of type 2 diabetes.
• 2. Patients with the diagnosis of non-proliferative diabetic retinopathy and the classified as mild and moderate.
• 3. Target eye best corrected vision acuity (BCVA) ≥ 34 points (ETDRS vision chart, vision equivalent of score 20 / 200, decimal 0.1).
• 4. Patients who meet the syndrome differentiation standards of yin asthenia generating intrinsic heat and eye collateral stasis in traditional Chinese medicine.
• 5. HbA1C ≤ 9%.
• 6. Age between 18 and 75 years old
• 7. Informed consent, voluntary subject. The process of obtaining informed consent form complies with Good Clinical Practice(GCP).

Exclusion Criteria:

• 1. Patient with the diagnosis of diabetic retinopathy is combined with severe vitreous blood effusion, or required total retinal laser treatment or vitrectomy.
• 2. Patient who has been treated with full retinal laser photocoagulation.
• 3. Patient with difficulty in evaluating fundus images with refractive medium turbidity.
• 4. Patient was diagnosed of acute metabolic disorders such as diabetic ketoacidosis or combined with severe acute infection in the past 1 month.
• 5. Patient with other serious diabetes complications, such as diabetes gangrene.
• 6. Patient was allergic to Tangningtongluo tablets, or Calcium dobesilate, or its composition.
• 7. Female patient with pregnancy, or prepare for pregnancy, or lactating.
• 8. Patient with serious cardiovascular, liver, kidney or hematopoietic system disease, and mental diseases.
• 9. Liver and renal function (Alanine aminotransferase (ALT) or Aspartate aminotransferase (AST) above 2 x Upper limit of normal (ULN)and Cr> above 1 x Upper limit of normal (ULN)). The diabetic nephropathy stage was 4 and above.
• 10. Patient with eye diseases such as glaucoma, uveitis, optic neuropathy, and severe cataract.
• 11. Patient participated in other clinical researches within a month.