Pars plana vitrectomy with silicone oil versus pars plana vitrectomy alone for postoperative endophthalmitis: A randomized controlled trial

PURPOSE: The role of silicone oil (SO) tamponade in pars plana vitrectomy (PPV) for postoperative endophthalmitis remains controversial. This study compared outcomes of PPV with SO versus PPV alone in severe cases, incorporating intraocular cytokine profiling and regression analysis. METHODS: In this prospective randomized controlled trial, 40 eyes with post-phacoemulsification postoperative endophthalmitis unresponsive to initial intravitreal antibiotics were randomized to PPV alone (n = 20) or PPV with 1000-cSt SO tamponade (n = 20). The primary outcome was change in best-corrected visual acuity (BCVA, logMAR) at 12 weeks. Secondary outcomes included recurrence of infection, retinal detachment (RD), and intraocular cytokine levels (interleukin [IL]-6, IL-8). Correlation and multivariate regression analyses were performed to identify predictors of final visual outcome. RESULTS: Final BCVA improved more in the SO group (1.5 ± 0.3 logMAR) compared with the PPV-alone group (1.7 ± 0.4 logMAR), although this difference was not statistically significant (P = 0.289). Recurrence was observed in two eyes (10%) within the SO cohort compared to eight eyes (40%) in the PPV-alone cohort (P = 0.021). At 8 weeks, intraocular cytokine levels were markedly reduced in the SO group (IL-6: 142 pg/mL vs. 298 pg/mL, P = 0.018; IL-8: 84 pg/mL vs. 176 pg/mL, P = 0.024). In the PPV-alone group, 8-week IL-6 levels strongly correlated with final BCVA (r = 0.712, P = 0.006). Multivariate regression identified recurrence of infection (β = 0.31, P = 0.009) and 8-week IL-6 levels (β = 0.001, P = 0.003) as independent predictors of worse visual outcomes. CONCLUSION: PPV with SO tamponade significantly reduces recurrent infection and intraocular inflammation in severe postoperative endophthalmitis, leading to trends toward improved visual outcomes. These benefits appear mediated by both anti-infective and anti-inflammatory mechanisms, supporting the use of SO in complex cases.