EyeWorld India December 2020 Issue

FEATURE 12 EWAP DECEMBER 2020 hydrorupture of the posterior capsule. In particular, Dr. Vasavada described inside-out delineation in which a central space is created in the nucleus and then fluid injected into the wall of that space (Figure 2) to eliminate the risk of subcapsular hydrodissection, making the procedure quite safe. Using a 90-degree bend cannula, fluid is injected into the wall of the trench that has been produced; the fluid demarcates the central nucleus. Chops Among the various chop techniques, Dr. Vasavada said that the horizontal chop, with a space or without a space in the middle, remains popular. However, they have found that the chop-in-situ technique, described in 1996 and later named the vertical chop, has the advantage of being suitable in a small rhexis and a small pupil. In a denser cataract, Dr. Vasavada recommended going “a little slower and in a step- by-step manner.” First, the phaco tip is buried into the lens material using the energy. A crack is then initiated by the chop-in-situ technique. The chopper is progressively positioned into the depth of the generated crack to extend it from the periphery to the center and from the anterior to the posterior plane. “This reduces the stress on the bag and zonules,” he said. Multilevel chop For cases with weak zonules and an extremely dense cataract where total division is very difficult, Dr. Vasavada described a multilevel chop technique (Figure 3) to minimize stress to the bag and zonules. “The chop action is generated by placing the phaco probe, occluding it in one plane, and then again burying the phaco probe in a deeper plane and achieving the crack,” he said. “In this process, both the chopper and the vacuum seal are generated at two different planes, and second plane being nearer to the hard bottom plate reduces the stress and achieves the complete division.” “This can be done in a vertical chop, horizontal chop, direct chop—any chop action this can be applied,” he said. “The initial crack is generated, and then phaco probe comes out of the lens material and gets buried again at a deeper plane with a very gentle movement. In this compromised zonule case, the crack is achieved and a total division is produced.” The same principles can be applied in a direct chop by burying the phaco probe initially in the peripheral part of the nucleus. Once the crack is generated and brought to the occluded tip, he said, the phaco tip comes out and gets buried again in a deeper plane, nearer the leathery bottom, and the crack is extended by using the chopper to produce a gentle lateral separation in the center portion, achieving total division up to the posterior plate. Cortex removal In terms of cortex removal, Dr. Vasavada finds that the position, occlusion, posterior detachment, and swiping (POPS) technique developed by Dr. Viraj Vasavada is quite safe to the bag and achieves complete cortex removal. An aspiration port is positioned under the anterior cortex. Pressing the pedal draws the anterior cortex to occlude the aspiration port. That aspiration port, occluded by the cortex, is then displaced posteriorly towards the posterior capsule, which will detach the anterior cortex from the anterior capsule. A swiping movement of that cortex will then detach that cortex from the fornix. This technique, Dr. Vasavada said, achieves a very thorough, clean removal, and, importantly, removes the epithelial cells. He described how Dr. Samaresh Srivastava has shown that doing a conventional radial pull sometimes break fibers in the fornix region, leaving epithelial Figure 3. With the phaco probe occluded at one plane, the chopper is brought down in a chopping action (A). The phaco probe is then released and is occluded at a deeper plane; the chopper again is brought down with gentle lateral separation to divide the nucleus all the way to the posterior plate. Source: Abhay Vasavada, MD