Residual silicone oil does appear after conventional removal and contributes to postoperative emulsification.

Purpose: To validate the presence of residual non-emulsified silicone oil (SO) following conventional surgical removal techniques used in vitreoretinal surgery and provide insights for optimizing surgical parameters and reducing subsequent emulsification-related complications.

Methods: The two surgical steps of repeated fluid-air exchange (FAX), including aspiration and infusion, were simulated in vitro to investigate their effectiveness in removing residual non-emulsified SO under various clinical settings. Aspiration was performed at three different positions with respect to the SO interface (i.e., within the SO phase, at the SO/BSS interface, and within the BSS phase) with a 25-gauge probe. An infusion was positioned near the SO/BSS interface with an intraoperatively standardized flow rate (5mL/min). In a further ex vivo study, the volume of residual non-emulsified SO (collected by Dichloromethane) was quantified by Flourier-transform infrared spectroscopy (FTIR) in both repeated FAX and passive drainage (PD) groups.

Results: In the in vitro model, regardless of which position a 25-gauge probe was located, residual non-emulsified SO could not be effectively removed even under high aspiration levels (p>0.05). Continuous BSS infusion led to small SO droplet formation. Residual SO in both non-emulsified and emulsified forms was observed in the ex-vivo model subjected to repeated FAX. The volume of residual non-emulsified SO was quantified, ranging from 2.75 to 24.71 μL, without significant difference among experimental groups (p>0.05).

Conclusions: Complete residual non-emulsified SO removal was technically challenging by conventional surgical techniques. This residual non-emulsified SO could serve as a source of ongoing SO emulsification.