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Case study illustrates advantages of advanced phaco technology
Elliptical phaco makes it possible for surgeons to take advantage of the efficiency of Venturi fluidics without compromising safety.
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Venturi fluidics offer a number of advantages in cataract surgery, particularly for the removal of nuclear segments. In terms of acquiring new nuclear components, a Venturi-style pump is superior to peristaltic pumps because of its ability to generate vacuum without occlusion. It has better holding ability at lower vacuum levels and can “extend” the surgeon’s reach, allowing the phaco tip to remain in the center of the pupil and draw pieces to it, reducing the potential for damage to the iris or capsular bag. Finally, at the conclusion of the procedure, Venturi fluidics provide for excellent clearance of residual ophthalmic viscosurgical devices and lens remnants, which is especially important to mitigate against postoperative IOP spikes.
Despite these advantages, cataract surgeons’ ability to use the Venturi vacuum safely was limited when only longitudinal or transversal phaco was available. Exclusively single-direction phaco allows for a more readily occludable needle, causing a buildup in vacuum and the potential for chamber instability or surge when the occlusion breaks. The greater the buildup of energy/vacuum during an occlusion event, the greater the resulting surge and risk of damage to the ocular structures.
Donald R. Nixon
Peristaltic systems gained prominence because of their ability to recognize and minimize occlusion events by adjusting fluidics or, more recently, phaco needle movement, despite the trade-off of lower efficiency. Surgeons were willing to make this trade-off to avoid a high-grade occlusion break with surge because it is difficult to stop the vacuum release before significant damage can occur. In short, safety over efficiency was a compromise that made sense in the era of single-direction phaco.
Bidirectional phaco
With the advent of bidirectional phaco, we no longer need to make this compromise. Both the Infiniti system with OZil Intelligent Phaco (Alcon) and the WhiteStar Signature system with Ellips FX (Abbott Medical Optics) make use of both a transversal and longitudinal motion of the phaco tip.
The Signature system uses a simultaneous but non-linear blend of longitudinal and transversal energy. As the power increases, as it would with a denser nucleus, there is more longitudinal energy, ensuring only micro- and not macro-occlusion events so that there is more of a continuous dynamic response. The Signature system with Ellips FX does not need peristaltic fluidics for occlusion recognition and thus allows for the option of Fusion Fluidics with a dual pump to use Venturi or peristaltic for some or all of the case.
Due to the ability of the Signature system to nearly eliminate high-grade occlusion, it is now possible to take advantage of both fluidics modalities in a single case depending on the surgeon’s preference. A recent case illustrates these benefits.
A post-vitrectomy eye
I recently performed cataract surgery on a 63-year-old man with high myopia and an axial length of 28.72 mm. He had a previous pars plana vitrectomy for treatment of a macular hole and a peripheral retinal break. There were some tears during the procedure, and the retina specialist chose to perform a complete vitrectomy with air-fluid exchange. As a result, I expected there would be a significant amount of trampolining or instability of the anterior chamber in this eye, mainly due to the vitrectomy but further aggravated by the length of the eye. This required a high level of chamber stability, and for that reason I chose to use a combination of ophthalmic viscosurgical devices (OVDs): dispersive Healon EndoCoat (3% sodium hyaluronate, AMO) for stability and retentiveness and cohesive Healon (sodium hyaluronate, AMO) to facilitate removal at the end of the case.
I removed the cataract using the Signature system with Ellips FX through a 2.2-mm incision employing a bent 21-gauge needle. In addition to the unique dynamic bend of the transversal and longitudinal elliptical motion of the needle, it also allowed for the use of both peristaltic and Venturi fluidics during the case. I believe there are significant benefits to this dual-pump technology for routine cases — benefits that are magnified in a complicated eye such as this one.
At the start of the case, I filled the periphery of the anterior chamber with a ring of cohesive OVD and then filled the remainder of the chamber with a dispersive OVD for stabilization and retention, which facilitated the capsulorrhexis. Phaco was then initiated with the peristaltic vacuum because I did not need to reach for anything inside the anterior chamber. The relatively low flow and controlled vacuum of peristaltic fluidics provided the stable environment required to remove epi-nuclear material, impaling the nucleus and chopping it into segments. Due to the dense cataract encountered, I used the dispersive OVD as a “visco-assist” to confirm a complete chop and separate the segments to facilitate removal. At that point, I switched to Venturi fluidics, which allowed me to work within the environment of the pupillary center, drawing out each one of the nuclear segments without disturbing the dispersive OVD that was anchoring the periphery and keeping the chamber stable. The phaco tip, given the excellent followability of Venturi, never went near the iris or capsule but remained within a 3-mm central “safe zone.” Despite the high axial length and post-vitrectomy status of the eye, the anterior chamber remained stable throughout the entire cataract procedure.
After filling the capsular bag with cohesive OVD, I implanted a Tecnis one-piece IOL 8 D (AMO) through the 2.2-mm incision. At the conclusion of the case, Venturi fluidics thoroughly removed all of the cohesive OVD and residual cortical remnants from the capsular bag, especially under the lens, to ensure the good contact and stable positioning essential for a premium IOL. I used a lasso technique by placing a ring of cohesive OVD in the periphery of the anterior chamber at the beginning of surgery before inserting the dispersive. Using the power of Venturi for aspiration and taking advantage of the natural followability of Healon, the lasso of cohesive OVD in the periphery is removed along with any residual nuclear material and dispersive OVD. This allows for the complete clearing of the anterior chamber.
The ability to switch on the fly between pump styles, and particularly the ability to use the Venturi vacuum in conjunction with Ellips FX phaco, facilitated a smooth and stable cataract extraction in what could otherwise have been a very unstable eye. The patient’s postoperative visual acuity was 20/30-2, which is an excellent visual result considering it was followed macular hole surgery.
Moving forward
I believe that the days of peristaltic-only and longitudinal-only phaco systems are limited. Converting to Venturi for all or part of the case confers great advantages in efficiency. With Venturi, followability is significantly enhanced, and a surgeon’s ability to acquire the next segment for removal is improved because the vacuum draws the segments directly to the needle. Finally, during irrigation and aspiration, Venturi fluidics extend surgeons’ reach and make this step safer and more efficient, ensuring a full clearance of OVD.
These are the same qualities Venturi has always offered. The difference is that advanced phaco technology now makes it safe for cataract surgeons to take advantage of the benefits of Venturi.