Intravitreal Methotrexate After Retinal Detachment Repair: A Canadian Retrospective Cohort Study of Feasibility and Safety

• First Canadian cohort describing intravitreal methotrexate (MTX) use after rhegmatogenous retinal detachment repair in eyes with proliferative vitreoretinopathy or high-risk features. • Visual acuity, anatomic status, and intraocular inflammation were followed for up to 12 months in a single-arm, retrospective cohort without a non-MTX control group. • Most complications were typical of complex vitreoretinal surgery, and MTX-specific adverse events appeared infrequent in this series. • Real-world variability in MTX timing, number of injections, and tamponade type highlights the need for standardized protocols and controlled trials to define efficacy. • These findings describe the feasibility of intravitreal MTX use in Canadian practice and provide descriptive safety data to inform future study design. To describe visual and safety outcomes after intravitreal methotrexate (MTX) following rhegmatogenous retinal detachment (RRD) repair in eyes with proliferative vitreoretinopathy (PVR) or high-risk features at a Canadian tertiary centre. Retrospective single-arm cohort from a single vitreoretinal practice with no non-MTX comparator. Charts from 2013 to 2025 were reviewed for RRD eyes that underwent pars plana vitrectomy and received serial low-dose MTX injections at 2, 4, 6, and 8 weeks. Eyes with PVR C or judged high risk for PVR were included. Visual acuity, anterior chamber inflammation, intraocular pressure, and complications were recorded for 12 months. The primary outcome was best corrected visual acuity at 6 months. Subgroup comparisons were exploratory and descriptive. Thirty-five eyes received MTX, 22 with PVR C, and 13 high risk without baseline PVR. Best corrected visual acuity improved at 6 and 12 months (both p<0.001). Intraocular inflammation decreased (p<0.001) and intraocular pressure was stable (p=0.5). Six eyes (17.1%) developed recurrent detachment. Twenty-three eyes (65.7%) had at least one complication, mostly expected after complex repair. MTX specific events such as corneal toxicity, persistent hypotony or uveitis were uncommon. Intravitreal MTX was used as a postoperative adjunct in complex RRD with PVR C or high-risk features. Outcomes and recurrence rates were similar to those of other complex PVR cohorts, but could not be attributed to MTX. This Canadian series provides descriptive safety and feasibility data that are hypothesis-generating and support the need for controlled trials.