Diabetic macular edema (DME) is the main cause of vision loss in patients with diabetes. At present, anti-vascular endothelial growth factor (VEGF) intravitreal injection is the first-line therapy for DME, nevertheless, some patients do not respond well to anti-VEGF agents and often require multiple injections, which increases the psychological and economic burden of patients. Microinvasive pars plana vitrectomy (PPV) has been proven to be safe and effective for refractory DME. However, there are few studies on treatment-naïve DME. The purpose of this study is to explore whether early PPV combined with internal limiting membrane (ILM) peeling can reduce the treatment burden of DME patients, prevent vision loss, and maintain long-term stabilization of diabetic retinopathy.
≥18 years of age
Patients and their families fully understand the research and sign the informed consent form
Diagnosed with type 1 or 2 diabetes mellitus
Hemoglobin A1c (HbA1c) of less than 10% within 3 months
Any previous DME treatment (i.e. anti-VEGF injections, intraocular corticosteroids, macular photocoagulation)
Macular edema caused by other disease (i.e. neovascular age-related macular degeneration, retinal vein occlusion, uveitis)
Any previous intraocular surgeries (cataract surgery performed at least 3 months before study entry will not be exclusionary)
Vision loss caused by other ocular disease (i.e. cataract, proliferative diabetic retinopathy, glaucoma, high myopia)
Parallel
Vitrectomy combined with ILM peeling
Procedure/SurgeryStandard 25-gauge PPV will be performed by an experienced surgeon under retrobulbar anesthesia. After clearing the central vitreous, a complete posterior vitreous detachment (PVD) will be achieved with aspiration to remove the tightly attached posterior hyaloid. The vitreous will be removed by a high-speed vitrectomy surgical system (Constellation Vision System, Alcon Laboratories, Fort Worth, Texas, USA). The ILM stained with indocyanine green (ICG) will be peeled up to the vascular arcades. In case of need, panretinal photocoagulation (PRP) can be performed during surgery. The vitreous cavity will be filled with balanced salt solution (BSS) at the end of the procedure.
Conbercept intravitreal injection
DrugPatients will receive three monthly intravitreal injections of 0.5 mg Conbercept (Chengdu Kanghong Biotech Co.) with a 30-gauge syringe needle approximately 3.5-4 mm posterior to the corneal limbus under topical anesthesia.
Best corrected visual acuity change (BCVA)
Early Treatment Diabetic Retinopathy Study (ETDRS) Alphabet Chart
Central subfield thickness (CST) change
Three-dimensional spectral domain optical coherence tomography (SD-OCT)
The stage of diabetic retinopathy (DR)
The grading and classification of DR will follow the International Clinical Diabetic Retinopathy and Diabetic Macular Oedema Disease Severity Scales. Ultra-wide field fundus photography will help investigators grade diabetic retinopathy.
Cost-effectiveness analysis
The incremental cost-effectiveness ratio (ICER) is used as the evaluation index in cost-effectiveness analysis. The average cost of the two groups of treatments is taken as willingness to pay (WTP). If ICER is less than WTP, the treatment scheme is cost-effective.
Vision-related quality of life questionnaire
The National Eye Institute Visual Functioning Questionnaire-25 (NEI-VFQ-25) will be used to evaluate the vision-related quality of life. Scores range from 0 to 100, and lower scores indicate a poorer quality of life.
Biomarkers of optical coherence tomography (OCT)
Scanning was centred on the macular fovea with a scan length of 6 mm. The resolution was 5 μm, the scan depth was 4 mm, and the scan mode was horizontal linear scanning of 512×128.
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