EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
Issue link: https://digital.eyeworld.org/i/220233
16 EW NEWS & OPINION November 2013 Tools & techniques The tri-soft shell technique by Steve A. Arshinoff, MD, and Richard Norman, BSc, MASc O phthalmic viscosurgical devices have been instrumental in improving the safety and efficacy of modern cataract surgery. One of the pioneers in helping us understand the individual intrinsic properties of these devices and their best means of utilization has been Steve Arshinoff, MD. In this month's column, Dr. Arshinoff and Mr. Norman present a beautifully written review of their latest iteration of the soft shell approach to modern phacoemulsification. The simple but elegant diagrams of all the various soft shell techniques should be clipped and saved along with a brief labeling of the various clinical presentations for which each technique is best utilized. I am sure that this article will be useful for us all, and I encourage surgeons currently not performing the tri-soft shell technique to give it a try. Richard Hoffman, MD, Tools & techniques editor O phthalmic viscosurgical devices (OVD) have revolutionized anterior segment surgery by facilitating surgical maneuvers through space creation while protecting the corneal endothelium. Since their introduction in 1979, the range of OVDs available has expanded significantly, offering an almost limitless variety of rheological properties. Thoughtful choice and application of OVDs allows the surgeon to anticipate and prevent complications in even the most complex cases. The tri-soft shell technique (TSST) is a generalization of multiple previously described soft shell approaches. It creates a rational OVDbased approach that can be adapted to address a wide range of surgical cases, from straightforward cataracts to complex cases such as intraoperative floppy iris syndrome (IFIS), Fuchs' endothelial dystrophy, or zonulysis. Its basis is that a single fluid is unable to achieve the same rheological performance as two or more fluids used together in a logi- cal planned approach, optimizing the selected OVD properties to the particular area of the anterior chamber where it is needed. The TSST leverages three different fluids to maximize surgical efficiency and control. A dispersive OVD (e.g., Viscoat, Alcon, Fort Worth, Texas) is used to protect the corneal endothelium, as dispersive OVDs have been found to be comparatively resistant to aspiration. However, dispersive OVDs are poor at space creation due to their lower viscosities. The TSST thus uses a viscoadaptive (e.g., Healon5, Abbott Medical Optics, AMO, Santa Ana, Calif.), which exhibits the highest zero-shear viscosity at low shear, to form a shell for space creation. A third fluid, balanced salt solution, is used to form a low resistance working area on the lens surface (pre-capsulorhexis step) and later within the capsular bag (pre-IOL implantation step). Maximizing the viscosity difference between two fluid layers reduces their propensity to mix, making it easier to maintain the soft shell structure. By creating a separate Figure 1: The tri-soft shell technique. A dispersive OVD is injected centrally (A). A viscoadaptive OVD is formed underneath this initial shell, displacing it upward (B). Injection of viscoadaptive OVD is continued until the pupil stops dilating. The dispersive OVD now coats the corneal endothelium (C). Balanced salt solution is injected adjacent to the lenticular surface, creating a low viscosity work area for capsulorhexis (D). After phacoemulsification and irrigation/aspiration of the lens, the viscoadaptive shell is rebuilt as needed to build a shell over the capsular bag (E). Balanced salt solution is used to fill the capsular bag, creating a space in which the IOL can unfold (F). Figure 2: Illustration of the various soft shell techniques (soft shell technique, SST; ultimate soft shell technique, USST; soft shell bridge, SSB; tri-soft shell technique, TSST). The soft shell configuration prior to phacoemulsification and prior to IOL insertion are illustrated for each approach. The TSST can be modified to each of the previously described soft shell techniques as desired by the surgeon. Source (all): Steve A. Arshinoff, MD, and Richard Norman, BSc, MASc aqueous layer directly adjacent to the lens, agents such as trypan blue or phenylephrine can also be delivered locally to the capsule and iris, avoiding dissemination in the anterior chamber. The tri-soft shell technique is performed as follows: 1. After creating the side-port incision, the eye is anesthetized and pressurized, and the pupil dilated, using 0.1 cc of xylocaine-phenylephrine mixture injected intracamerally. The phaco incision is then created. 2. The dispersive OVD is injected through the phaco incision to form a central mound on the surface of the anterior capsule, stopping once the anterior chamber (AC) is about 25% full (Figure 1A). A second viscoadaptive layer is then injected beneath the dispersive onto the surface of the anterior capsule (Figure 1B). This displaces the dispersive shell upward against the corneal endothelium, creating a smooth, protective shell (Figure 1C). Injection of viscoadaptive should continue until the pupil stops dilating but before the eye becomes firm. 3. Balanced salt solution, or the xylocaine-phenylephrine mixture, is then injected slowly underneath the viscoadaptive layer, with the cannula directed downward toward the lens surface (Figure 1D). This creates a pool of low viscosity fluid directly on the lenticular surface. The viscoadaptive shell is displaced upward and backward toward the incision, creating a central bridge and blocking the incision. In cases of white or brunescent cataract, trypan blue may be painted on the capsular surface prior to the balanced salt solution layer to enhance visualization. 4. A routine capsulorhexis is performed using a bent needle (less likely to displace the shells) or forceps. Because this takes place within the low viscosity balanced salt solution pool, resistance is minimized when manipulating instruments or the capsular flap. 5. Hydrodissection is performed with balanced salt solution using