Reply: Experimental study comparing 2 different phacoemulsification systems with intraocular pressure control during steady-state flow and occlusion break surge events

Field: Medicine (Health Sciences)

Thank you for your letter and the opportunity to provide further clarification on our study. The Centurion with Active Fluidics was chosen as one of the study arms because it represented the largest share of the market. We selected the Quatera 700 for the second study arm because it was the only other major system that provided IOP control. Our plan is to conduct multiple studies. This first study establishes a baseline with a focus on key fluidic fundamentals pertaining to different design approaches: The Quatera uses a synchronized infusion/aspiration pump. By contrast, both the Centurion with Active Fluidics and with Active Sentry use a pressurized infusion bag methodology and restricted tubing. Active Sentry is a premium upgrade that offers a lower surge profile, but this advantage is limited to the ultrasound (US) mode only. We appreciate you sharing your positive experience with your Centurion systems. We are also aware of positive reports from Quatera users. We do not dispute these favorable perceptions and subjective findings. To provide further insight and a better depth of understanding of the fluidics, we conducted a scientific study in a controlled laboratory setting. We did not include clogging as part of the study. From a physics perspective, we simply noted that a larger-bore tube provides the potential for faster tissue removal and is less likely to clog than a smaller-bore tube. This did not mean to imply that there is a serious clogging issue with the small-bore tubing. We are not aware of any significant clogging issues with the tubing or US tips for either product. (Note: Centurion did have clogging issues with its flared tip, but this was mitigated using IP software.1) You state in your letter that a higher vacuum is required for the Quatera. We respectfully disagree. It is quite the opposite. Both the Centurion with Active Fluidics and with Active Sentry use small-bore tubing, which requires an ∼32% higher level of vacuum to achieve the same flow result as the Quatera. For example, at a flow rate of 40 mL/min, Quatera required ∼205 mm Hg vacuum. By contrast, the Centurion indicated a higher vacuum of 270 mm Hg to achieve the same flow rate result even with a larger diameter US tip (Figure 1).Figure 1.: Passive vacuum vs aspiration flow rate.The Quatera 700 provides true active incision leakage compensation. The Centurion with Active Fluidics does not. It neither monitors incision leakage nor actively compensates for it. It simply provides an IOP offset akin to raising the bottle. Incision leakage compensation is only available on the Centurion with the Active Sentry upgrade.2 We agree that there may be advantages of operating at a lower IOP. The Quatera had shorter surge duration times than Centurion at all IOP and vacuum settings. For example, at a setting of 30 mm Hg IOP and 600 mm Hg vacuum, the Quatera had a notably shorter surge duration time of 408 milliseconds compared with 913 milliseconds for the Centurion.3 We appreciate the opportunity to provide a better understanding of the underlying fluidics of these two IOP-based systems. Thank you.