Technology: Next-generation vitrectomy is here

New York-Results from a series of bench studies evaluating a new 25+-gauge (g) vitrectomy probe (UltraVit, Alcon Laboratories) and trocar system (EdgePlus, Alcon Laboratores) highlight the benefits and improved performance of this technology compared with previous instrumentation for microincision vitrectomy surgery (MIVS), said Allen C. Ho, MD, at the 2009 Retina Congress.

"MIVS offers potential advantages that include faster wound healing and increased patient comfort. However, there have been some drawbacks," said Dr. Ho, of Mid Atlantic Retina, and professor of ophthalmology, Wills Eye Institute, Thomas Jefferson University, Philadelphia. "Relative to larger probes, the 25-g instruments have less flow, slower maximum cut speeds, and are considered flimsy by some surgeons.

Surgical impressions

"The findings from this controlled investigation confirm our surgical impressions that the new 25+-g probe and trocar system successfully address these issues and represent a significant advance for improving the safety, ease, and efficiency of MIVS," Dr. Ho said.

The faster flow rates with use of the new 25+-g probe and enhanced equipment are attributable to a larger aperture of the vitreous cutter probe, wider inner diameters of the Luer fitting and tubing, and elimination of a dimple in the cannula. Compared with the previous trocar system, the new system has a reconfigured blade and new ergonomic handle that improve the ease and architecture of incision creation. Initial entry is facilitated with a pointed lead edge, and a more distal central ridge pulls the tissue into the trail edge to create a clean, widened, straight incision.

Probe performance studies compared the 25+-g probe against 25- and 23-g probes (UltraVit) using a new multifunctional platform for vitreous surgery (Constellation Vision System, Alcon Laboratories) and enhanced equipment with the 25+-g probes.

Flow rates were determined using six probes of each gauge with methodology to account for infusion cannula restrictions and fluid dynamics of the globe.

The studies were performed with cut speeds ranging from 1,000 to 5,000 cpm, vacuum levels of 200 to 650 mm Hg, and at the core, 50/50, and shave duty cycle modes.