VITREORETINAL SURGERY
Insights

Vitreous Surgery Technology: Choice and Consistency During Surgery Are Key

By Gaurav K. Shah, MD, co-director retina fellowship, The Retina Institute, St. Louis, MO, USA

Vitrectomy surgery technology should allow surgeon choice and provide consistent fluidics during the surgery. Now that vitrectomy surgery has evolved into an elegant procedure, surgeons are increasingly looking at ways to decrease the vortex that is created within the eye during a vitrectomy procedure, largely through increased stability and consistency of the fluidics employed.

Optimal cutter performance

We are looking forward to obtaining first-hand experience using the EVA VacuFlow VTi (Valve Timing intelligence) system (DORC International) for microincision vitrectomy surgery and in a range of different pathologies involving the vitreous, especially in combination with the accompanying two-dimensional cutting (TDC) vitrectome, which provides cutting speeds of up to 16,000 cuts per minute (CPM), reducing traction on surrounding tissue and allowing ultra-efficient vitreous removal.

Comparative evaluation of small-gauge vitrectomy cutters measuring flow rates at varying cut speeds
Aspiration flow rates at varying cut rates for different small-gauge vitrectomy cutters, measured in BSS @ vacuum of 550 mmHg.
Source: DORC International

Increased cut rates undoubtedly help to achieve low vitreous traction in vitrectomy surgery. During vitreous cutting, we need to make sure that the amount of traction we put on the retina is minimized. While optimal high-speed vitreous cutting is critical, the central issue ultimately is to minimize pressure fluctuations within the eye.

For delicate phases of vitreoretinal surgery, my preference is to have more control of fluid aspiration, which is provided by a flow controlled pump system, providing constant, consistent and predictable flow into the port. And that becomes especially important when working close to the retina, for example in patients with retinal detachment or peripheral vitreous abnormalities.

Commercially available technologies for vitrectomy surgery are predominantly vacuum-based systems. I think that as surgeons gain experience with flow-based aspiration technology, they will quickly start to appreciate the benefits of having the additional choice of flow control without the pulsatile vacuum. When performing a core vitrectomy, I would rather have constant consistent movement where the instrumentation port is always occluded with vitreous, without peaks and valleys. I want a steady state in the eye, with minimal traction.

Broadened capabilities

With the EVA system, surgeons can utilize either the vacuum or the flow control mode, or combination of flow control and vacuum control, in a single fluidics system. The machine incorporates an intelligent flow control system, adjusting to the particular media environment at any given moment. This is an advantage, as with other vitrectomy machines and cutters, surgeons have the option of one approach only.

Most vitreoretinal surgeons should be able to operate successfully with whatever vitrectomy machine they happen to have in place. But I certainly believe that maximum surgical safety is paramount during vitrectomy. The EVA aspiration system is designed to provide the capability to achieve flow control vitrectomy and also allow a vacuum mode approach, with very fast response time, as and when required.

Comparison TDC vitrectomes vs classic style
Design of DORC International’s TDC vitrectome vs. conventional vitreous cutter: with the TDC vitrectome, vitreous is brought into the inner aperture and cut in a forward and then backward motion, increasing the amount of vitreous cut in a single motion.
Source: DORC International

Surgeons can therefore choose whatever mode works best for them — in certain cases such as core vitrectomy, surgeons may opt to use the vacuum mode, while in other situations they may prefer a peristaltic-type flow control mode for increased precision, for example when there is a mobile retina. The EVA platform offers welcome diversity by giving surgeons the ability to choose between two distinct control modes using a single fluid control system. All surgeons want the option to exercise choices in order to maximize surgical control and overall safety parameters. ■