AIM: To assess the relationship between serological parameters and the prognosis of young patients with retinal vein occlusion (RVO) after intravitreal conbercept injection (IVC). METHODS: This study enrolled 100 young patients (≤50 years old) diagnosed with RVO-related macular edema (RVO-ME) who had been undergoing IVC at the 474 Hospital in Xinjiang between January 2022 and October 2023. Patients were categorized into two groups: 70 eyes in the effective group and 30 eyes in the ineffective group. The effective group comprised patients exhibiting a visual acuity improvement of ≥2 lines at the last follow-up, with resolved ME and central macular thickness (CMT) <300 μm. Conversely, the ineffective group included patients with visual acuity improvement of <1 line, persistent ME, and CMT ≥300 μm at the last follow-up. Serological parameters, including white blood cell count, neutrophil count, lymphocyte count, monocyte count, and mean platelet volume were assessed before treatment. The correlation between best-corrected visual acuity (BCVA) and neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), systemic immune inflammation index (SII), and systemic immune response index (SIRI) was analyzed. Additionally, the association between these serological parameters and the efficacy of IVC was explored. RESULTS: Three months after treatment, the effective group demonstrated a significant improvement in BCVA from 0.82±0.20 to 0.36±0.10, with a concurrent decrease in CMT from 661.28±163.90 to 200.61±82.45 μm (P<0.001). Conversely, the ineffective group exhibited minimal changes in BCVA (0.86±0.25 to 0.82±0.14) and CMT (669.84±164.95 to 492.13±138.67 μm, P<0.001). The differences in BCVA and CMT between the two groups were statistically significant (P<0.001). According to subgroup analysis, in patients with central RVO (CRVO), BCVA improved from 0.82±0.23 to 0.49±0.12 in the effective group and from 0.80±0.18 to 0.76±0.22 in the ineffective group (P<0.001). The CMT changes followed a similar pattern. In patients with branch RVO (BRVO), comparable trends in BCVA and CMT changes were observed between the effective and ineffective groups (P<0.001). Additionally, the effective group exhibited higher PLR and SII values than the ineffective group (P<0.05). Further CRVO and BRVO subgroups analysis exhibited consistent PLR and SII value trends. CONCLUSION: Compared to other inflammatory factors, elevated PLR and SII levels before treatment are better predictors of outcomes in young RVO-ME patients undergoing IVC treatment.