EyeWorld Asia-Pacific December 2016 Issue

December 2016 EWAP FEATURE 19 hydrodelineation to remove the central lens endonucleus, followed by viscodissection of the leftover lens epinucleus and cortex.” The key, she stressed, is to move slowly. In addition, Dr. Chan emphasized the need to keep the anterior chamber formed so that there is no sudden pressure change that would cause the posterior capsule to vault anteriorly, leading to a torn capsule in the central weakened zone. “Thus, when withdrawing the phaco tip, I would inject viscoelastic through the paracentesis,” she said. In addition, to prevent excessive pressure on the posterior capsule, she would lower the bottle height during irrigation/aspiration. “Finally, once the IOL is inserted and I’ve finished removing the cohesive viscoelastic, as I withdraw the I/A probe, I would inject balanced salt solution through the paracentesis to ensure that the paracentesis stays formed,” she said. “You could also pre-hydrate the wounds before removal of the final viscoelastic so that they do not leak.” She finds that this decreases the risk of collapsing the anterior chamber. When Dr. Safran treats posterior polar cataracts, he likewise modifies his technique to avoid hydrodissection. “You want to gently hydrodelineate from the center avoiding aggressive distention of the capsular bag,” he said, stressing that surgeons shouldn’t try to cleave a plane between the cortex and the posterior capsule because that could lead to trouble if there’s a preexisting defect there, which is present in about 20% of cases. In cases where there is a defect, the later in the case that it is revealed, the safer the surgery is. In other cases, where there is no congenital hole, the capsule adjacent to the posterior capsule plaque may be somewhat weaker and more prone to breaking. “You want to leave the epinucleus or cortical shell behind so that the plaque stays with it until the very end of the case,” Dr. Safran said. “After I remove the central nucleus, I remove the epinucleus and the plaque may come with it. If it does not, I leave it.” After removing the central nucleus, if there is a sheet of epinucleus or thick cortical shell remaining, one can use a little peripheral hydrodissection or viscodissection to separate this from the posterior capsule. “Then you peel off that last sheet and hope there’s not a hole there,” Dr. Safran said, adding that most of the time there isn’t. “If there is, using your other hand, you try to gently inject viscoelastic and tamponade it back,” he said. With a hole, a vitrectomy may ultimately be necessary no matter how good the technique is. To avoid rupture, in some cases the surgeon may want to leave the plaque and go back at a later time with YAG, Dr. Safran advised. The plaque is usually at the center of the lens in the back, sitting on the posterior capsule. “If you don’t aggressively hydrodissect that layer, you have a good chance of preserving it,” he said. “If you have a soft lens, you can hydrodelineate it like an onion outward. But if it’s a dense nuclear sclerotic cataract, it’s tricky because there’s no way you can get the hydrodelineation in those middle layers, so you may Views from Asia-Pacific Samaresh SRIVASTAVA, MD Consultant, Raghudeep Eye Hospital A-16, Shanti, Path Tilak Nagar, Jaipur, India Tel. no. 9099026161 samaresh@raghudeepeyeclinic.com P osterior polar cataracts (PPC) are a challenge for every cataract surgeon due to their propensity for posterior capsule dehiscence and weakness. Although the initial reported incidence of posterior capsule rupture (PCR) was anywhere between 26 to 36%, subsequent improvements in understanding of techniques and technology have led to a reduction in the rates of PCR to 6 to 7%. Depending on the clinical presentation, PPC can be divided into three categories: (1) Polar cataracts without evident posterior capsule dehiscence; (2) polar cataracts with preexisting posterior capsule dehiscence; (3) spontaneous dislocation. Posterior polar cataracts without evident dehiscence comprise 97% of all polar cases and are the most common presentation in patients under 40 years of age. A number of surgical approaches have been proposed for emulsification of PPC. The final surgical goal for every surgeon is to be able to safely remove the entire cataract and implant an intraocular lens (IOL), preferably in the capsular bag. In order to protect the inherently weak posterior capsule, the strategy for posterior polar emulsification involves: - avoiding rapid buildup of hydraulic pressure within the capsular bag, - creation of a mechanical cushion above the weak capsule, and - adherence to the principles of closed chamber technique. Cortical cleaving hydrodissection is usually avoided in these eyes as a rapidly passing fluid wave can lead to a sudden buildup of hydraulic pressure within the capsular bag and lead to blowout of the posterior capsule. As a result, most surgeons prefer to perform conventional hydrodelineation or inside-out delineation to generate a plane of separation within the nucleus, as well as avoid buildup of pressure on the posterior capsule. However, most of these techniques depend on injection of fluid within the nucleus to create a mechanical cushion. As the femtosecond laser technology promises to enhance precision and outcomes in cataract surgery, we have recently explored the application of this technology to enhance safety in posterior polar cataracts 1 . Using the femtosecond laser platform for cataract surgery, the cylindrical pattern of lens division is chosen to create multiple cylinders within the lens. This leads to creation of sharply demarcated layers within the nucleus. The number, size, and depth of these cylinders can be controlled by the surgeon using the live anterior segment optical coherence tomography view. The multiple layers act as mechanical cushions that allow removal of each layer within the protection of the other. Finally, the last epinuclear layer that is left behind can be easily stripped off using a combination of phaco probe and bimanual irrigation/aspiration due to its sharp demarcation. This approach eliminates the need for any kind of hydro procedure in posterior polar cataracts. It reduces PCR rates and enhances safety in posterior polar cataract emulsification. Our PCR rates have dropped from 8% to 4.4% after adopting the femtodelineation approach. Reference 1. Vasavada AR, et al. Femtodelineation to enhances safety in posterior polar cataracts. Journal of Cataract & Refractive Surgery . 2015 Apr;41(4):702–7. Editors’ note: Dr. Srivastava declared no relevant financial interests. continued on page 20