EyeWorld Asia-Pacific June 2014 Issue

17 June 2014 EWAP FEAturE Views from Asia-Pacific CHEE Soon Phaik, MD Senior Consultant, Singapore National Eye Centre 11 Third Hospital Ave., Singapore 168751 Tel. no. +65-6227-7255 Fax no. +65-6227-7290 chee.soon.phaik@snec.com.sg P ublished literature suggests that femtosecond laser created corneal incisions, arcuate keratotomies and nucleus fragmentation during cataract surgery is arguably safer than conventional surgery. Although there are potential benefits of a well-sized, round and centered capsulotomy, initial reports of incomplete capsulotomies and even dropped nuclei highlight the fact that this technology is evolving and that there is a learning curve. My experience is limited to the Victus(Bausch+Lomb/Technolas, Rochester, NY, U.S./Munich, Germany) laser platform. Our center acquired the laser in mid 2012. The docking system on this platform (which uses a two-piece coupling system with a small liquid interface) then had the smallest suction clip. To date, we have successfully treated over 1,300 cases without a single failure to dock. I agree that docking is a very important step that determines the completeness of the capsulotomy. The laser energy setting must be adequate to cut the capsule and nucleus, and should be increased in the presence of corneal opacities, capsule fibrosis and nuclear brunescence. There is a learning curve to achieve a flat dock. In the Victus, the operating microscope helps the surgeon achieve centration of the patient interface on the cornea. Centration of the corneal ring reflex on the crosshairs and maintaining the light reflex circular during gentle docking ensures flat docking and eliminates corneal folds, respectively. Holding the patient’s head to maintain the docking position and reminding the patient not to move their eyes are also important. In eyes with eccentric pupils, the capsulotomy may be decentered and thus a manual override should be used. Small pupils result in downsized capsulorhexes which require enlargement after insertion of the intraocular lens. In the extreme pupil, I have used a Malyugin ring which can be inserted prior to femtolaser treatment. Mild subconjunctival hemorrhage can be minimized by gentle docking, not exceeding the recommended docking pressure. The “dimple-down” technique has been described to check capsulotomy completeness. However, when incomplete, the posterior pressure may induce a capsule tear outwards. I prefer to pull centripetally when there is a tag, and circumferentially to round off a bridge. Hydrodissection should be gentle especially when there is a significant amount of bubbles trapped in the bag, uncommon with the Victus except when treating very dense nuclei. Cortical clean-up is more difficult as it is necessary to place the aspiration port beyond the capsulotomy rim in absence of a cortical frill. Aspirating a missed out “dog-ear” capsule tag may induce an anterior capsule rip (ACR). If the capsulotomy edge is irregular, bimanual irrigation and aspiration (IA) is preferred to coaxial IA for removal of subincisional cortex to avoid stretching the capsulotomy edge. In the presence of an ACR, maintaining the anterior chamber space and careful cortex removal at the rip are important to avoid posterior capsule extension. After the initial learning curve, ACRs are rare. I prefer using the femtosecond laser for handling white cataracts, mild to moderately subluxated cataracts and posterior polar cataracts. Others have also recommended its use for pediatric anterior and posterior capsulotomies. Editors’ note: Prof. Chee is a consultant for Bausch+Lomb and Technolas Perfect Vision. Sudeep DAS, MD Senior Consultant, Cataract & Refractive Surgery, Narayana Nethralaya Bangalore 121/C Chord Road, 1st R Block, Rajajinagar, Bangalore, India – 560010 Tel. no. +91-9480587929 Fax no. +91-8023377329 drsudeepdas@gmail.com I have been using the LenSx laser (Alcon, Fort Worth, Texas, U.S.) for close to 3 years. I do not have any financial interest in the product or the company. Both the software and hardware have evolved considerably since then. In the early days, incomplete capsulotomies were common. One had to be extremely careful in removing the anterior capsule flap for fear of the capsulotomy running off to the periphery. The other common complication during the initial learning curve was the very anterior placement of the incisions which made phacoemulsification difficult and induced astigmatism and higher order aberrations. With practice and with the introduction of the SoftFit PI these problems are history. The most common complication is that of subconjuctival hemorrhages. Almost all my patients develop this even with the new PI. But the other complications have all but disappeared. In the last 2 years I have had free floating capsulotomies in all patients except for two. Both were in extremely intumescent cataracts, where the high intralenticular pressure made the capsulotomy run to the periphery even before I entered the eye. Before performing a manual rhexis, we pressurize the anterior chamber with high molecular weight OVDs, thus flattening the anterior capsule. This does not happen in FLACS and can be a problem in highly intumescent cataracts. This is counteracted to some extent by the speed of the capsulotomy which is less than 2 seconds in the LenSx. The other potential complication is that of incomplete nuclear division in white cataracts. The HD OCT in the LenSx is amazing and one can image the posterior capsule even in these. The capsulotomy is perfect in non-intumescent mature cataracts but the nucleus division may not be complete. The difficulty is more in finding the laser cuts in the nucleus with so much of the white fluffy cortical matter in front. If one takes time to aspirate all of this material one can actually find the laser cuts and these are more often than not complete. Based on my earlier experience with incomplete division of the posterior plate, I am very aggressive in brown cataracts and keep the posterior offset at 500 microns or less. This creates complete nuclear division through the posterior plate. Anterior incisions are a problem in patients with large arcus senilis. Increasing the internal illumination helps to identify the limbus more easily. This is helped by marking the limbus with a marking pen in two quadrants before docking. I have had a rhexis tear extending to the posterior capsule in a patient with an intumescent cataract and that is the only PCR I have had with FLACS. Tilted dock is a complication when one is unable to communicate with the patient. I had this with a patient who did not understand any of the six languages that I speak. Even with an interpreter I needed multiple attempts to get an acceptable if not perfect dock. Editors’ note: Dr. Das has no financial interests related to his comments.