EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
Issue link: https://digital.eyeworld.org/i/276058
E W CATARACT 72 March 2014 by Sumit (Sam) Garg, MD Review of phacoemulsification: Two case studies P hacoemulsification for cataract removal is one o f the most common and effective procedures per- formed in all of medicine with an exceptionally high success rate. 1 However, it is beneficial to periodically review the mechanics of the procedure and the aspects criti- cal to successful outcomes, in both standard and complicated cases. I n the following two cases I use the same tools in slightly different ways to meet the distinct needs of each patient. Case study 1 This is a typical patient in her mid- 60s with declining vision found to be consistent with a visually signifi- cant cataract. Surgery started with a standard temporal 2.75 mm incision followed by intracameral lidocaine and use of Healon EndoCoat OVD (Abbott Medical Optics, AMO, Santa Ana, Calif.). This incision size allows me to use my preferred 20-gauge an- gled tip with a purple high infusion sleeve. The capsulorhexis was uncomplicated, and I made sure to hydrate well to get a good spin on the nucleus. Using the WhiteStar Signature system (AMO), I began phacoemulsification in peristaltic mode, which allows me to impale the nucleus and hold it in place with the handpiece while I maneuver the chopper around the side of the nucleus for a horizontal technique. I find this method to be highly re- producible, thus asserting a level of safety. Peristaltic fluidics are flow based and I am able to achieve ex- cellent holdability of the nucleus while generating vacuum when the phaco tip is occluded. In this case, I remained in peri- staltic mode to divide the nucleus i nto four quadrants, then switched to venturi mode. Venturi fluidics are vacuum based, with the flow being the passive parameter. With venturi fluidics, occlusion is not necessary to generate vacuum at the tip, allow- ing improved followability. This allows me to retain the handpiece near the middle of the eye while the n uclear segments come to me. I use the chopper for the minimal manip- ulations required to move nuclear segments toward the aspirator. During aspiration of the nuclear fragments, I keep the second instru- ment, in this case the chopper, be- hind the probe. This is a preemptive action in the event chamber insta- bility occurs, and helps to reduce the chance of posterior capsule tear. I remain with venturi for cortex removal. I prefer linear foot pedal control of the vacuum, allowing me to polish without needing a separate polish setting. It is important to be cognizant of wound architecture to maintain chamber stability. Fluidics are set based on the anticipated amount of wound leakage combined with aspi- ration rate, and a snug wound with less gape maintains a stable cham- ber. A snug wound is achieved by entering and exiting both the main and paracentesis incisions so that the incision site is not extended with the blade. Extending the wound even 0.1 or 0.2 mm can have a dramatic effect on how fluidics work. If I notice flattening or bounce in the chamber when I de- press the pedal, it may be necessary to raise the bottle height to equalize the mismatch between inflow and egress. O nce the lens is removed, I make the eye firm with viscoelastic and perform intraoperative aberrom- etry measurements to aid in final lens selection. I routinely use Tecnis (AMO) three-piece lenses because I feel the lens optics are great, the lens centers beautifully, and I appreciate the flexibility for the patient down t he line if there is ever any trauma or capsular bag instability. Case study 2 This patient in his mid-70s pre- sented with a cataract so dense it had become very difficult to visual- ize the fundus. In this patient, I used trypan blue to stain the capsule following the 2.75 mm temporal incision. I used a small air bubble to move the dye around and make sure it was pushed up against the anterior capsule before removing the major- ity of the dye so that there were no pockets. Following the injection of viscoelastic, I performed the capsu- lorhexis and then hydrodissection using a Chang cannula (Katena Products, Denville, NJ.). Using this c annula I am able to hydrodissect and spin with the same instrument, increasing efficiency. With dense nuclei, I refill the anterior chamber with a dispersive viscoelastic prior to phacoemulsification for extra en- dothelial protection. As with a less complex nuclei, I begin with the peristaltic mode and make a hori- z ontal chop, impaling the nuclei while maintaining vacuum. In this patient, posterior fibers reduced the efficacy of the first chop, requiring me to rotate 90 degrees and chop again on a different meridian. Again I aim to impale directly in the center of the nucleus. I rotated an addi- tional two clock hours and impaled the nucleus again, at which time I decide to give myself more space by removing the first fragment while still in peristaltic mode. I then switched to venturi mode to remove the remaining segments. Denser nuclei tend to chip off some, and venturi mode helps to keep the little but that generally goes away by the next day." Overall, Dr. Uy views the liquid adhesive bandage as a boon for cataract surgeons. "I think the take- home message is that we found an excellent way of sealing a leaky wound, that is rapid, doesn't induce astigmatism, and provides patient comfort," he said. "In our practice we have the OcuSeal in the OR and anytime we encounter a wound that's difficult to close we open it up, apply it, and continue on to the next case." The whole process he estimates takes about 30 seconds. Going forward, Dr. Uy expects to be conducting new trials into potential use of OcuSeal for retinal or strabismus surgery. "I think there will be more applications of this product as time goes by," he said. EW Editors' note: Dr. Uy has no financial interests related to this article. Contact information Uy: harveyuy@yahoo.com Sticking continued from page 71 Clinical.EWrePlay.org This is a typical patient in her mid-60s with declining vision found to be consistent with a visually significant cataract. This patient in his mid-70s presented with a cataract so dense it had become very difficult to visualize the fundus. Searchable video number 228 Searchable video number 229 Go to clinical.ewreplay.org for the latest clinical videos. 64-75 Cataract_EW March 2014-DL2_Layout 1 3/6/14 3:10 PM Page 72