The goal of this clinical trial is to clarify the efficacy of anti-vascular endothelial growth factor (anti-VEGF) drugs combined with subthreshold micropulse laser (SML) therapy on retinal function and anatomical recovery in patients with diabetic macular edema (DME). The main questions it aims to answer are:

• To clarify the efficacy of anti-VEGF drugs combined with SML therapy on retinal function and anatomical recovery in DME patients.
• To explore the changes in visual acuity and optical coherence tomography angiography (OCTA) parameters before and after the treatment of DME with anti-VEGF drugs combined with SML, and further explore the changes in morphological characteristics of retinal microvessels and the potential treatment mechanism.

Participants will randomly be given Intravitreous injection of anti-VEGF drugs or anti-VEGF drugs combined with SML therapy. All participants will be followed up for 6 months after treatment.

Inclusion Criteria:

• Patients with non-proliferative diabetic retinopathy (NPDR) meeting diagnostic criteria: the diagnosis can be made by fundus examination, fluorescein fundus angiography (FFA) and optical coherence tomography (OCT), which meet the clinical significant macular edema (CSME) definition criteria, i.e. hard exudation within 500μm of macular fovea with adjacent retinal thickening or edema within 500μm of macular fovea. Or the thickened area of the retina was > 1 disc diameter (D) and within 1 day of the fovea of the macula.
• OCT examination showed a thickened CMT (≥200μm) without hyperplasia or scar
• Standard logarithmic visual acuity charts measure the BCVA (LogMAR) range from 0.01 to 1.0
• Control of glycosylated hemoglobin (HbA1c) ≤10% during follow-up
• Patients voluntarily participate and sign informed consent

Exclusion Criteria:

• Patients with severe corneal opacity, cataract and vitreous hemorrhage were found to be affected by OCTA examination by ophthalmic examination.
• Patients with other eye diseases or other complications during follow-up, such as glaucoma (IOP>21mmHg), high myopia (≥-6.0D), and other fundus lesions, such as retinal detachment, vitreous macular traction, preretinal membrane, ischemic macular disease, optic neuritis and other diseases involving the retina and optic nerve.
• Patients who have previously received intraocular surgery, vitreous macular traction syndrome, proliferative diabetic retinopathy (PDR) resulting in vitreous hemorrhage or local retinal detachment requiring surgical treatment, and patients with a history of eye trauma.
• History of panretinal photocoagulation within 6 months prior to treatment or local/grille photocoagulation within 3 months prior to treatment.
• History of intravitreal injection of any steroid within 6 months prior to treatment.
• Patients with serious systemic diseases, such as cardiovascular and cerebrovascular diseases or hematopoietic system, patients who have undergone intracranial surgery or intracranial space-occupying lesions, and patients with mental disorders.
• Can not cooperate with the ophthalmic examination or other reasons can not obtain the ideal OCTA image.
• Pregnant, pregnant or lactating women and patients allergic to drugs.
• Suspected or confirmed history of alcohol and drug abuse.
• Patients who are participating in clinical trials of other drugs. If one of the above meets and can be excluded.