Comparison of the silicone oil removal rate between vitrectomy and manual syringe negative pressure approach

The purpose of this study was to compare the silicone oil removal rate between vitrectomy and manual syringe negative pressure approach. Thirty-five silicone oil-filled eyes were enrolled and allocated for manual (n = 19) and vitrectomy (n = 16) removal approaches. For manual approach, a 10-ml syringe was connected to the 23-gauge cannula through a short section of blood transfusion tube. Removal was started after pulling and fixing the plunger to the end part. The syringe was pulled away immediately once the residual of silicone oil cannot be observed through the cornea. For vitrectomy approach, the only difference was the source of negative pressure, i.e., the blood transfusion tube was connected to the cannula directly to remove the silicone oil. Silicone oil removal rate was defined as the volume of silicone oil divided by the time taken for removal. The mean time taken for silicone oil removal was faster for manual approach than vitrectomy approach (4.13 +/- 1.41 vs. 6.14 +/- 1.49, p = 0.001). Furthermore, the silicone oil removal rate was larger for manual approach (1.42 +/- 0.30 vs. 0.90 +/- 0.16 ml/min, p < 0.001). No severe intraoperative or postoperative complications were noted for both approaches. The mean IOP at day 1 after surgery was significantly lower than that at baseline in both groups (manual group 10.2 +/- 4.5 vs. 17.6 +/- 5.9, p < 0.001, vitrectomy group 15.1 +/- 7.5 vs. 8.3 +/- 1.9, p < 0.002). All the eyes were recovered at 1 week after surgery. The best-corrected visual acuity (LogMar) at 1 month postoperatively improved compared to that preoperative for both approaches (manual group: 1.10 +/- 0.62 vs. 1.47 +/- 0.76, p = 0.07; vitrectomy group: 1.10 +/- 0.47 vs. 1.11 +/- 0.50, p = 0.62). Both approaches are safe for silicone oil removal. The manual approach is more convenient and efficient.