Abstract
Purpose :
Silicone Oil (SiOil) removal is one of the most time consuming stages during surgery. Ultrasonic vitrectomy cutters have shown to be capable of removing SiOil, while pneumatic cutters prove ineffective. The mechanism of action that makes this possible is previously unknown. We show here, for the first time, the fluidic action that is enabled by ultrasonic energy in aspirating SiOil. Ultrasonic vitrectomy devices like Vitesse can be further optimized for oil extraction and may offer an advantage over existing oil extraction methods with shorter aspiration times.
Methods :
5000 PaS SiOil with a density of 0.96 g/cm3 was injected into an imaging container to form a drop, weighed, and then submerged in BSS. After SiOil extraction, BSS was removed by evaporation on a hot plate. The remaining SiOil was then weighed again.
The ultrasonic vitrectomy cutter used was a 23 gauge Vitesse probe, operated at 29.6 kHz, 60 um stroke, and 600mmHg vacuum, while the pneumatic cutter was operated at 15 kcpm and 600 mmHg vacuum. High speed video with 100,000 frame rate captures the microscopic action and fluidics velocity was calculated by the particle tracking method.
Results :
Vitesse port operating on the interface of SiOil and BSS showed the capability to remove SiOil at a rate of 0.18 ml/min. Full port submergence in the oil was ineffective at removing the oil with a rate of 0.02 ml/min. Pneumatic cutters were ineffective at removing SiOil regardless of the port position. SiOil velocity was measured at 14 cm/s, and BSS velocity was measured at 30 cm/s.
Conclusions :
Ultrasonic operation provides SiOil aspiration through mechanical motion of the port edges which separates it from the oil and allows BSS aspiration. The BSS in turn, acts as a carrier and propagates the SiOil up the small diameter needle probe and the aspiration line. Optimized port geometry may facilitate faster SiOil aspiration using the BSS-oil boundary method.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.