The Influence of Fluids With Varying Rheological Properties on the Field of Fluidic Effect During Vitrectomy.

Purpose: The purpose of this study was to investigate the field of fluidic effect (FOE) at the vitrectomy port in a range of artificial vitreous solutions (AVS) with varying rheological characteristics to add insight into the effects surgeons observe during vitrectomy and how they change with a variety of console settings.

Methods: Laboratory-based investigation using in vitro testing was carried out at Newcastle University, United Kingdom. Testing was conducted using an Eva Nexus Vitrectomy system (D.O.R.C. Dutch Ophthalmic Research Center [International] B.V., Zuidland, The Netherlands) using dual cutting action vitrectomy probes in 3 gauge sizes (23G, 25G, and 27G). Using AVS, particle image velocimetry (PIV) measurements were conducted for various console settings and AVS concentrations.

Results: Rheological analysis of AVS with varying hyaluronic acid concentrations showed shear thinning and viscoelastic properties, resembling the liquid component of human vitreous humour. PIV during vitrectomy revealed that a dual cutting probe created a focused, elongated jet stream in AVS, contrasting with the symmetrical flow in balanced salt solution (BSS). Key findings included peak fluid velocity magnitude in AVS was 0.5 to 1 mm from the port, broadening with increased vacuum, higher vacuum led to inferior jet deviation, cut rates increased peak velocities, with viscoelasticity influencing fluid flow dynamics, and increasing hyaluronic acid concentration transitioned flow from BSS-like to elongated jet profiles.

Conclusions: Using an AVS with similar rheological properties to the liquid component of human vitreous and a high-speed PIV technique, we evaluated the FOE around vitrectomy probes with a range of surgical relevant variables. Further research into the influence of different vitreous substitutes and surgical parameters is crucial to enhance our understanding and refine vitrectomy procedures.

Translational Relevance: Our findings provide valuable insights into the fluid dynamics during vitrectomy, helping to optimize surgical techniques and improve patient outcomes.