Evaluation of RC28-E Injection in Diabetic Macular Edema

Inclusion Criteria: * Sign the consent form, willing and able to comply with clinic visits and study-related procedures; * Aged 18 years to 80 years, male or female; * Diabetes mellitus(type 1 or 2); * The study eye must followed: 1. Retinal thickening secondary to diabetes mellitus (DME) involving the center of the fovea; Decrease in vision determined to be primarily the result of DME and not to other causes. 2. BCVA score in the study eye of 73 to 24 using the ETDRS protocol at an initial testing distance of 4 meters. 3. The central subfield thickness ≥300μm in the center subfield as assessed on OCT by the reading center; * If both eyes meet the inclusion criterion, one eye with poor BCVA is selected as the study eye; the researchers judged that the fellow eye should not be treated with other anti-VEGF drugs recently. Exclusion Criteria: * The macular edema caused by others instead of diabetes mellitus; * Structural damage to the center of the macula in the study eye that is likely to preclude improvement in BCVA following the resolution of macular edema including atrophy of the retinal pigment epithelium, subretinal fibrosis or scar, significant macular ischemia or organized hard exudates; * Current iris neovascularization, vitreous hemorrhage, tractional retinal detachment or epiretinal membrane involving the macula in the study eye; * Only one functional eye even if that eye is otherwise eligible for the study; * Evidence of periocular or intraocular inflammation or infection including infectious blepharitis, keratitis, scleritis, conjunctivitis, endophthalmitis or uveitis at screening assessment in either eye; * Previous treatment with anti-angiogenic drugs in either eye or system (ranibizumab, aflibercept, conbercept, etc) within 3 months of the Day 0; * History of cardiovascular and cerebrovascular events within 6 months of screening visit: myocardial infarction, unstable angina pectoris, ventricular arrhythmias, New York heart association grade II + heart failure, stroke, etc.; * Uncontrolled clinical disease (such as severe psychiatric, neurological, cardiovascular, respiratory disease or other systemic diseases) and tumors; * Those who participated in clinical trials for 3 months or 5 half-lives of the investigational product (the longer the time) before the baseline period; * Those who considered unsuitable for enrollment by investigator.