Mecobalamin Combined With Anti-VEGF Intravitreal Injection for Retinal Vein Occlusion Treatment

Condition(s) studied

Investigational drug(s) / intervention(s)

Anti-VEGF drug: conventional anti-VEGF therapy (intravitreal injections of conbercept 0.5 mg initially once a month for 3 months, followed by on-demand therapy which based on recurrence criteria)

Mecobalamin 5 MG: oral mecobalamin capsules 0.5 mg three times daily for 6 months

Placebo: placebo capsule with a similar appearance and odor to the mecobalamin capsules three times daily for 6 months

Study summary

Retinal vein occlusion (RVO), a common retinal vascular disease, is frequently treated with anti-vascular endothelial growth factor (anti-VEGF) agents as first-line therapy. However, anti-VEGF monotherapy lacks neuroprotective effects, primarily targets vascular leakage and neovascularization, and requires frequent long-term injections that impose substantial economic burdens. Combined therapeutic strategies addressing both vascular pathology and neural damage are therefore being explored.

This article describes the protocol for a randomized, outcome-blinded, placebo-controlled clinical trial evaluating mecobalamin (a widely used neuroprotective drug) in combination with anti-VEGF for the treatment of macular edema (ME). A total of 120 eligible RVO patients will be enrolled from the First Affiliated Hospital of Chongqing Medical University. Participants will be randomly assigned (1:1) to an experimental group and a control group. The experimental group will receive conventional anti-VEGF therapy plus oral mecobalamin capsules for 6 months, while the control group will receive the same anti-VEGF treatment plus a placebo for 6 months. All patients will undergo one year of follow-up after initial treatment, with visits at 1, 3, 6, 9, and 12 months.

The primary outcome is the change in central subfield thickness (CST) from baseline to one year post-initial treatment. Secondary outcomes include:

* Change in best-corrected visual acuity (BCVA) from baseline over time,
* Capillary density,
* Cone photoreceptor distribution characteristics,
* Mean light sensitivity and fixation stability,
* Serum vitamin B12 levels,
* Number of anti-VEGF treatments,
* Injection frequency (times per year),
* Treatment interval,
* Incidence and severity of adverse events (AEs) and serious adverse events (SAEs).

This trial evaluates a novel "neuroprotection + vascular intervention" strategy combining mecobalamin with anti-VEGF therapy. The trial aims to provide high-level evidence for synergistic RVO treatment, with the potential to reduce recurrence rates and improve long-term visual function prognosis.

Eligibility

Primary outcome measure(s)

• Anatomical indicators-central foveal thickness — From enrollment to the end of treatment at 1 year
  the changes in central foveal thickness from baseline to 1 year post initial treatment.The primary outcome is the change in central subfield thickness (CST), measured via spectral-domain optical coherence tomography (SD-OCT), from baseline to 12 months post-initial treatment. CST will be defined as the mean retinal thickness within the central 1-mm diameter subfield of the ETDRS grid (Early Treatment Diabetic Retinopathy Study), automatically segmented and calculated using device software (e.g., Heidelberg Spectralis® or equivalent). All OCT scans will be performed by certified technicians following standardized protocols, including quality control for signal strength (\>7/10), proper centering, and absence of artifacts. Measurements will be verified by masked graders at a central reading center.

Trial sites (1)

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