Early Vitrectomy vs PRP in Early Proliferative Diabetic Retinopathy

Diabetic retinopathy is a leading cause of vision impairment worldwide, particularly among working-age adults. The development of retinal neovascularization in proliferative diabetic retinopathy (PDR), including neovascularization at the disc (NVD) and neovascularization elsewhere (NVE), is associated with a high risk of vitreous hemorrhage, tractional retinal detachment, and severe vision loss.

Current standard treatment for early PDR includes panretinal photocoagulation (PRP) with or without adjunctive anti-vascular endothelial growth factor (anti-VEGF) therapy. While PRP has been shown to reduce the risk of severe vision loss, it is associated with several limitations, including peripheral visual field loss, reduced night vision, exacerbation of macular edema, and incomplete regression of neovascularization in a substantial proportion of patients. Anti-VEGF therapy requires repeated intravitreal injections and may be associated with treatment burden and variable response.

The vitreous body plays an important role in the pathophysiology of PDR by providing a scaffold for neovascular growth and contributing to the persistence of vascular endothelial growth factor (VEGF) within the vitreous cavity. Microincision vitrectomy surgery (MIVS) may offer potential therapeutic advantages by removing the vitreous scaffold, facilitating the clearance of VEGF, and improving intraocular oxygenation. These mechanisms may contribute to more effective regression of retinal neovascularization and reduction in disease progression.

This study is a multicenter, prospective trial designed to compare early MIVS intervention with standard PRP in patients with early PDR. Eligible participants will receive either MIVS combined with peripheral photocoagulation or standard PRP. The surgical procedure will be performed using small-gauge (25G or 27G) instrumentation with high-speed vitreous removal. In the experimental group, scattered photocoagulation will be applied to the far peripheral retina during surgery. In the control group, PRP will be delivered in accordance with standard clinical practice over multiple sessions.

Participants will undergo standardized follow-up evaluations over 12 months. Retinal neovascularization will be assessed using fundus fluorescein angiography (FFA) or optical coherence tomography angiography (OCTA). Functional outcomes, including best corrected visual acuity (BCVA) and visual field cumulated values , will be measured using standardized protocols. Structural outcomes such as central retinal thickness will be assessed by optical coherence tomography (OCT).

To enhance the reliability of outcome assessment, retinal imaging will be obtained using standardized acquisition protocols and evaluated by trained graders when feasible.

This study aims to generate clinical evidence on whether early surgical intervention with MIVS can improve neovascular regression and functional outcomes compared with PRP alone in early PDR, thereby informing optimal treatment strategies for this patient population.

Inclusion criteria

• Age 18 years or older.

Diagnosis of type 2 diabetes mellitus.

Presence of early proliferative diabetic retinopathy with active neovascularization, or mild vitreous hemorrhage or preretinal hemorrhage that does not interfere with evaluation of neovascularization.

Relatively clear optical media, good pupillary dilation, and sufficient cooperation for panretinal photocoagulation and retinal imaging.

Ability and willingness to provide written informed consent.

If both eyes are eligible, the eye with worse vision will be included.

Exclusion criteria

• Prior panretinal photocoagulation, macular photocoagulation, or vitrectomy in the study eye.

Retinal traction or retinal detachment.

Optic neuropathy.

Macular edema caused by reasons other than diabetes.

Coexisting ocular disease that may decrease visual acuity during the study.

Substantial cataract likely to decrease visual acuity by more than three lines.

Major ocular surgery within the past 4 months or planned intraocular surgery within the next 6 months.

YAG capsulotomy within the past 2 months.

Any intravitreal injection within the past 3 months.

Aphakia.

Severe external ocular infection.

Uncontrolled glaucoma.

Significant renal disease requiring dialysis or kidney transplantation.

Unstable glycemic control.

Blood pressure greater than 180/110 mmHg.

History of transient ischemic attack, stroke, myocardial infarction, acute congestive heart failure, or other acute cardiac event requiring hospitalization within the past 4 months.

Pregnant, lactating, or intending to become pregnant during the study period.

Participation in another clinical trial.

Unwilling or unable to provide informed consent, undergo randomization, or return for scheduled visits.