RESIDUAL SILICONE OIL DOES APPEAR AFTER CONVENTIONAL REMOVAL AND CONTRIBUTES TO POSTOPERATIVE EMULSIFICATION

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

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

In the in vitro model, regardless of which position a 25-gauge probe was located, residual nonemulsified SO could not be effectively removed even under high aspiration levels ( P > 0.05). Continuous balanced salt solution infusion led to small SO droplet formation. Residual SO in both nonemulsified and emulsified forms was observed in the ex vivo model subjected to repeated fluid-air exchange. The volume of residual nonemulsified SO was quantified, ranging from 2.75 to 24.71 µ L, without significant difference among experimental groups ( P > 0.05).

Complete residual nonemulsified SO removal was technically challenging by conventional surgical techniques. This residual nonemulsified SO could serve as a source of ongoing SO emulsification.