Sometimes in IOL implantation, especially with more flexible IOL designs, capsular phimosis can result from the inadequate removal of lens epithelial cells from under the anterior capsular rim. I have found that the Allegro single-use silicone I/A handpiece (MicroSurgical Technology; Figure 1) can be used to reduce this risk.
I believe silicone is the standard-of-care material for I/A tips and safer than metal. Robert H. Osher, MD, demonstrated this in a video, which showed how metal I/A tips can form microscopic burrs due to routine maintenance and how these burrs can then cause potentially dangerous capsular tears.1 The Allegro tip, preassembled and encased within a single silicone sleeve, is free of abrupt borders that can inadvertently hang up on anatomic structures. With the Allegro, I have increased confidence each time the tip passes through the capsulotomy.
DOING THINGS BETTER
The Allegro’s uniform conic design, converging to a smooth parabolic tip, enables me to do several things better than I could with previous I/A tips. I can go under the anterior capsular rim with enhanced confidence that I will not unintentionally grab the capsule. I can also perform aspiration 360° around the capsular rim by simply rotating the handpiece. The silicone sleeve smoothly traverses over the capsular rim because there are no abrupt transitions.
The tip not only affords excellent removal of cortex for 360°, but it also improves polishing and removal of residual lens epithelial cells from under the anterior capsular rim, which may reduce the incidence of capsular phimosis. This is particularly pertinent with flexible IOLs such as the Crystalens (Bausch + Lomb), but it is important in every case of IOL implantation because it is always desirable to maintain capsule clarity and reduce postoperative capsular phimosis. This is a crucial element of successful cataract surgery because capsular contraction can potentially interfere with lens positioning and even reduce the effective optical zone.
The aspiration port of this silicone I/A tip is positioned 90° from the handle axis, placing it ideally for both anterior and posterior capsule polishing. The Allegro design also avoids an issue inherent in previous designs, whereby fluid could squeeze out of the seam between the sleeve and the central core tube and inadvertently push away cortical material.
INTRAOPERATIVE, POSTOPERATIVE BENEFITS
The Allegro’s ability to facilitate improved cleaning of the capsule, leading to reduced likelihood of fibrosis and phimosis, also increases the potential for tighter refractive outcomes. When capsules are clearer and there is less contracture, the effective lens position and, consequently, the refractive outcome are likely to be more predictable.
The importance of completely removing OVD from behind the lens implant cannot be underestimated, especially with toric IOLs. When I slip the Allegro behind the IOL, I can depend on it to move smoothly without hanging up on the optic edge. With previous designs, there was a greater risk of inadvertently pushing the implant during this maneuver and therefore stressing the zonules. The smooth design helps to avoid intraoperative rotation of toric IOLs.
1. Lipner M. How to improve cortical removal with the new silicone tip. http://www.eyeworld.org/printarticle.php?id=319. Accessed May 16, 2016.
Barry S. Seibel, MD
• Founder, Seibel Vision Surgery, Los Angeles
• Financial disclosure: Consultant (Bausch + Lomb, Abbott Medical Optics)