The effectiveness of vitrectomy co-adjuvant intravitreal dexamethasone implant on visual outcome in patients with proliferative diabetic retinopathy: study protocol for a prospective randomized controlled trail

Background : Proliferative diabetic retinopathy (PDR) often leads to tractional retinal detachment and vitreous hemorrhage, requiring vitrectomy. Poor visual outcomes are commonly caused by macular edema and proliferative vitreous retinopathy after vitrectomy. Intravitreal dexamethasone implant has shown promise in improving visual function after vitrectomy for diabetic macular edema, but its role in vitrectomy in PDR treatment remains unexplored. This study aims to assess the effectiveness of vitrectomy combined with intravitreal dexamethasone implant for PDR patients. Methods : We designed a single-blind, randomized controlled trial with 100 participants diagnosed with PDR requiring vitrectomy. Participants were randomly assigned to either the dexamethasone implant group or the control group. The dexamethasone implant group underwent vitrectomy combined with intravitreal dexamethasone implant, while the control group underwent vitrectomy alone. The single surgeon performed all the vitrectomy surgeries, the choice of intravitreal dexamethasone implant treatment was disclosed before the closure of scleral wounds. Primary and secondary outcomes were assessed at baseline, 4 weeks, and 8 weeks post-vitrectomy. Primary outcome measures included corrected visual acuity (Snellen visual chart) and central retinal thickness (optical coherence tomography OCT). Secondary outcomes included elevated intraocular pressure, post-vitrectomy hemorrhage, retinal detachment, and systemic complications requiring hospitalization. Discussion : This protocol seeks to enhance our understanding of the effects of combined intravitreal dexamethasone implant with vitrectomy on visual outcomes and macular morphology changes in treating late complications of PDR. The trail was registered at Chinese Clinical Trial Registry at May 11 th 2022 with registration number ChiCTR2200059760.