EyeWorld Asia-Pacific December 2014 Issue

December 2014 11 EWAP FEATURE Dr. Page creates a groove until he sees a glimmer of a red reflex at the bottom of the groove. “Then I know I have gone deep enough that I can crack it,” Dr. Page said. He advises practitioners to place the needle and chopper at the deepest point of the groove. At that depth, he recommends slowly separating the two instruments in a lateral fashion. “Once the surgeon sees a clear red reflex without attachments between the two fragments, there is no need to apply further lateral motion,” he said. These lenses will not conform to the confines of the capsular bag. “An over-aggressive lateral separation of the two fragments could potentially result in a capsular rent,” Dr. Page said. If the lens is so dense that you cannot safely pass a chopper through, Dr. Page recommends making a quick groove and then rotating this 90 degrees and making a second one. This becomes the divide-and-conquer technique. Some surgeons prefer to use a nuclear cracker device. “The advantage of using a cracker is that it has 2 paddles that can align with the groove and provide an alternative technique to separate the 2 hemispheres,” Dr. Page said. When removing these dense lenses, he modifies his phaco power from a maximum of 30 and a pulse setting of 40 pps, with a 50% duty cycle up to a 65% duty cycle. This way the phaco power is on a little longer but is still not continuous, thereby minimizing the amount of energy going into the eye. Dr. Pettey, likewise, makes some phaco adjustments with dense lenses. In particular he worries about zonulopathy. When dealing with morgagnian white cataracts that are hypermature and intumescent, Dr. Pettey lowers the bottle height and also the aspiration rate. However, if it’s just a dense lens, he does not alter fluidics but does make other adjustments. “If we’re talking about just a 4+ dense lens, I’ll increase both the power and the torsional energy,” he said. “One thing I’ve also found helpful is to use a pulse modality of about 6 milliseconds on and 6 milliseconds off, and that seems to allow for the most efficient phaco.” In conjunction with this, Dr. Pettey likes to use an ultrasonic prechopper for most dense lenses. “This is a modified phaco tip with a sharp end that allows for the creation of very small grooves,” he said. Use of the Akahoshi prechopper (Asico, Westmont, Ill., U.S.) enables the nucleus to be divided into 4 or 6 sections before quadrant phacoemulsification, allowing for efficient removal. In cases where Dr. Pettey is concerned that the phaco energy is going to be too much for the endothelium or if the patient has Fuchs’ dystrophy with a hypermature dense lens, he switches to manual small incision cataract surgery also known as sutureless extracapsular cataract surgery. One potential concern with this approach is that the capsulotomy does not have the consistent lens overlap that you can get with phaco, Dr. Pettey said. Also, because of the larger wound, the astigmatism changes can be a little bit more variable, he finds. There can also be complications using the ultrasonic prechopper. “We did a study here that showed that wound Views from Asia-Paci c Sudeep DAS, MD Senior Consultant, Narayana Nethralaya 121/C Chord Road, 1st Block Rajajinagar, Bangalor, Karnataka, India – 560096 Tel. no. +919480587929 drsudeepdas@gmail.com B eing in the developing world, dense brown cataracts are fairly common. In our setting, operating on four or ve of these every day is common. I agree with Dr. Page that the potential complications and sequelae of cataract surgery in these eyes such as corneal edema, compromise of the capsule– zonule complex, the inability of implanting an intraocular lens and the necessity of more than one surgery should be clearly explained. Dr. Page has succinctly explained the methods of differentiating a bad optical biometry from a good one. Even in extremely dense nuclear cataracts, it may be possible to get a good optical biometry in the absence of posterior subcapsular or cortical component. One would require an immersion A-scan in a fairly large proportion of patients. I would use the keratometry from the optical biometry and the axial length from the ultrasound machine. A direct vertical chop is possible in almost all cataracts but only in very experienced hands. Everyone else should, as Dr. Page mentions, make a deep trench before attempting to crack the nucleus. Not only is the red glow visible, one can also see a change in the consistency of the lens at the bottom of the trench, from the compact endonucleus to the more crumbly, granular epinucleus. Once this is reached, one could bury the phaco tip deep down into the front or side of the trench and apply a lateral force deep down in the trench with the second instrument. This way the nucleus is stabilized and will not tilt backwards during the cracking maneuver. The pulse mode phaco as described is the safest to use and causes least wound burns. The burst mode can be used for very effectively emulsifying these cataracts without clogging of the tip. A good dispersive OVD such as Viscoat or a viscoadaptive OVD such as Healon 5 should be injected many times into the anterior chamber during nucleus emulsi cation to protect the corneal endothelium. As mentioned, the parameters have to be brought down before removing the last piece. Dr. Pettey mentions the use of manual SICS which is a good technique provided one has a large rhexis. In black cataracts, even the largest of rhexes may not be large enough and one would require relaxing cuts to prevent zonular dialysis. Postoperatively one would require more frequent steroid drops and often anti- glaucoma medication. Editors’ note: Dr. Das has no nancial interests related to his comments. continued on page 12