EyeWorld China December 2019 Issue

ROLE OF FLUID DYNAMICS IN CATARCT SURGERY Intraoperative fluid dynamics influence the intraocular pressure (IOP) fluctuations and therefore the postoperative outcomes in cataract surgery. A prolonged increase in IOP is associated with anterior segment inflammation and IOP fluctuations during cataract surgery increase the risk of posterior capsular rent, a potentially sight-threatening intraoperative complication. Constant measurement and maintenance of IOP during cataract surgery is therefore crucial. Recent improvements in the science and technology of fluid dynamics have opened new avenues for cataract surgeons allowing them to customize fluidics settings with wider range of target IOPs while maintaining chamber stability. Active Sentry ® Handpiece Technology and Intrepid ® Hybrid Tip David Lubeck Posterior capsular rupture (PCR) is associated with physical, economic and emotional consequences such as prolonged surgery, increased inflammation, need for additional surgery and decreased visual outcomes. PCR can occur during phacoemulsification, irrigation and aspiration, posterior capsule polishing, most commonly due to inadvertent contact between phaco tip and capsule, explained Dr. David Lubeck, an ophthalmic expert from Arbor EyeCare, USA. Active Sentry ® is the first and only hand piece with a built in intra- ocular pressure sensor that directly measures intraoperative IOP in real-time and communicates with enhanced Active Fluidics to actuate immediate adjustments to maintain anterior chamber stability. 11 The Intrepid ® hybrid balance tip is a polymer over-moulded titanium tip with no sharp metal edges, which reduces the likelihood of capsular tear. One lab study showed that 55% phaco power was required to rupture a capsule with a hybrid tip compared to only 15% with a metal tip. 12 The combined Hybrid tip and Active Sentry™ technology provides The combined Intrepid Hybrid tip and Active Sentry™ technology provides significant advantages during cataract surgery (Table 1), explained Dr. Lubeck. “A technology that uses a safer phaco tip and provides superior chamber stability with less surges will be highly beneficial in reducing the risk of PCR. That’s where the Active Sentry ® handpiece technology and Intrepid ® Hybrid Tip comes in to play.” Dr. David Lubeck Table 1: Advantages of Combined Hybrid tip and Active Sentry ® technology 1. Allows phacoemulsification closer to the capsule 2. Allows higher aspiration flow rate and vacuum 3. Facilitates surgery at physiologic IOP 4. Simplifies surgery in high risk and unstable eyes (myopia, pars plana vitrectomy or trabeculectomy, traumatic cataract) 5. Decreases likelihood of damage to iris in intraoperative floppy iris syndrome (IFIS) and small pupil eyes The Intrepid ® Hybrid tip and Active Sentry ® technology allows the surgeon to have real-time control in the handpiece to facilitate surgery at preferred or physiologic IOP, maintain chamber stability and reduce the risk of capsular tears thus improving patient safety and satisfaction during cataract surgery. Active Sentry ® and dynamic real-time IOP measurements in rabbit eyes Abhay Vasavada * Kruskal Wallis Test used Dr. Abhay Vasavada, an eye expert from the Raghudeep Eye Hospital in India presented the anecdotal results of his study using dynamic real-time IOP measurements in 30 rabbit eyes comparing phacoemulsification with two types of fluidic systems, the Active fluidics™, which offers IOP control through pressure sensors in irrigation and aspiration line; versus Active Sentry ® Handpiece, which features a built-in pressure sensor that reacts in real time. It communicates with the hardware and software to compensate for changes in the anterior chamber, remarked Dr. Vasavada. The study aimed to record real-time, dynamic IOP during nucleus removal using two types of active fluidic systems; and also compare the time taken to recover to baseline IOP following occlusion break surge in both systems. Standard surgical technique with standardized IOP and vacuum setting was used in both groups. While Active fluidics™ was associated with larger IOP fluctuations with wider slope to recovery from drop of IOP, Active Sentry ® was associated with smaller IOP fluctuations, with narrower slope to recovery from drop of IOP. The IOP during fragment removal and rate of drop of IOP following occlusion break response was lower in the Active Sentry ® group. (Figure 3) The rate of recovery of IOP following occlusion break response was also faster with Active Sentry ® . Group Mean (+ SD) IOP (mmHg) % Reduction from Maximum IOP (Mean) Group I – Centurion Vision System 53.6 + 7.2 35 Group II – Active Sentry ® with Centurion Vision System 51.7 + 6.6 31 P Value 0.05 0.03 * Kruskal Wallis Test used Figure 3: Lower IOP and lower rate of drop of IOP following occlusion break response with Active Sentry ® Active Sentry ® provides the surgeon with control at fingertips to lower absolute IOP and facilitate better mitigation of occlusion break surge during cataract surgery. “A technology that allows the surgeon to preset lower IOPs and mitigate intraoperative IOP fluctuations is advantageous during cataract surgery." Dr. Abhay Vasavada