Diabetic macular edema (DME) is an important cause of central vision impairment among people with diabetic retinopathy (DR), which can have a significant adverse effect on daily activities and quality of life. Diabetic patients with preexisting DME are at increased risk of worsening edema following cataract surgery. Previous studies also reported progression of DR after cataract surgery. Clinically significant DME is now classified into center-involved DME (CI-DME) and non center-involved DME (non-CI DME). Randomized clinical trials have established intravitreal antivascular endothelial growth factor (VEGF) therapy as first-line treatment for visual impairment from CI-DME and studies have addressed the influence of anti-VEGF therapy among patients with DME undergoing cataract surgery. However, for patients with non-CI DME before cataract surgery, whether anti-VEGF therapy is necessary at the end of surgery to prevent CI-DME is still clinically controversial. In order to evaluate the prophylactic effect of Conbercept (a recombinant fusion protein with high affinity to all VEGF isoforms and PIGF) intravitreal injection at the conclusion of cataract surgery for DME in patients with DR, the investigators will prospectively recruit 40 cataract patients with DR and non-CI DME and randomly assign these subjects into the study group (combined cataract surgery and intravitreal Conbercept injection, 20 cases) and the control group (cataract surgery alone, 20 cases). The primary outcomes include mean changes in central retinal thickness (CRT) and in diabetic retinopathy severity score (DRSS). The secondary outcomes include changes in best corrected visual acuity (BCVA), foveal avascular zone (FAZ), retinal vessel density (VD), the aqueous concentrations of VEGF, PIGF, interleukin- (IL-) 2, IL-5, IL-6, and IL-8.

Inclusion Criteria:

• Patients sign informed consent, and are willing and able to comply with all the follow-ups
• Age ≥ 18 years , both genders
• Diagnosis of type 1 or type 2 diabetes mellitus
• Serum HbA1c ≤ 10%
• Patients with a diagnosis of DR (ETDRS 35-53) and cataract

Exclusion Criteria:

• CI-DME
• Any other ocular disorder in the study eye that may cause macular edema excluded the diabetic retinopathy
• History of allergic reaction to fluorescein, protein agents for diagnosis or therapy, or more than 2 drug or nondrug factors, or concomitant allergic diseases
• Received anti- VEGF treatment (including intravitreal injection or systematic application) within three months prior to enrollment
• History of panretinal laser photocoagulation (PRP) in the study eye 6 months prior to enrollment, or possibly need panretinal photocoagulation of the study eye during the study
• Intraocular conventional surgery within the past three months
• Traumatic cataract or congenital bilateral cataract in the study eye
• Active ocular or periocular infection in either eye
• Iris neovascularization in the study eye
• Uncontrolled glaucoma, or history of glaucoma surgery
• Aphakia in the study eye
• History of vitrectomy in the study eye
• The density of corneal endothelial cells is lower than 2000/mm2
• Patients with uncontrolled hyperglycemia, or Hemoglobin A1C (HbA1c) ≥10.0%, or under hemodialysis, or started insulin usage within the last 4 months, or expected to start insulin use for hyperglycemia control in the next 4 months
• Any surgical contraindications
• Uncontrolled Blood Pressure
• Myocardial infarction, heart failure, stroke, or transient ischemic attack within one month
• Renal Failure
• Pregnant or breast-feeding women
• Participation in another simultaneous medical investigator or trial
• Other situations where the researcher judges that the patient is not suitable for inclusion