Two decades ago, Dr. Kunihiro Nagahara defined phaco chop, a technique that made cataract surgery more efficient. He proposed the use of mechanical energy to disrupt the cataract nucleus into smaller portions instead of using the traditional the technique of divide-and-conquer.
Phaco chop needs less ultrasonic energy to disassemble the nucleus, which involves less harm to the corneal endothelial cells, resulting in less inflammation and a faster recovery after surgery. The technique is simple to learn, however, some cataract surgeons have chosen not to adopt it.
As Dr. Kunihiro Nagahara mentioned in a recent news release, he taught the technique during the past 15 years to surgeons as part of their training. Currently, the majority of surgeons who use the divide-and-conquer method are skilled in using a second instrument in the eye for the cracking portion of the nucleofractis technique. As such, being trained in phaco chop is relatively easy for these surgeons.
The traditional Nagahara technique is a horizontal chop, where the primary plane of movement is horizontal, parallel to the lens and iris surface. This technique is dissimilar from a vertical chop procedure, where the aim it to spread a crack vertically, towards the posterior capsule.
In an article published by Uday Devgan, MD, in Ocular Surgery News U.S. Edition, horizontal chop was discussed, a technique that can be used in a wide range of nuclear densities and functions with most chopping tools.
The chopper is a small tool that avoids touching the posterior capsule of the lens when placed at the equator of the nucleus. For the phaco probe to grip the cataract nucleus as the chopper divides it, surgeons need to adjust the platform settings. The vacuum level must in the range of 300 mm Hg to 500 mm Hg, but this depends on the size of the phaco tip. To facilitate the removal of the nuclear portion, the flow rate and the bottle height/infusion pressure need to be stable and at an adequate range, and the power of the ultrasonic phaco is dependent on the nucleus density, with a denser nucleus necessitating more power.
When capsulorrhexis (a continuous circular tear in the anteriorcapsule during cataract surgery) is generated and hydrodissection is executed to move the nucleus, the proper position of the chopper is the first and more critical move that surgeons need to preform. This tool is required to be positioned around the lens equator, under the edge of the capsulorrhexis, and if the iris is not dilated to its maximum this view may be buried.
In the article, the author recommends that beginners should slide the chopper around the lens anterior surface and then surgeons should push the edge of the capsulorrhexis until the tip of the chopper reaches the equator of the lens. At this stage of the procedure, the chopper will marginally drop as it touches the equator of the lens and the capsulorrhexis will put it back into its position. This is the point where the chopper it at its correct place, and it can be placed before spearing the nucleus with the phaco probe.
When surgeons get more experienced with the technique, they can improve it by adding some methods such as placing the chopper at the same time as the phaco probe impales the nucleus utilizing the phaco probe to push one nuclear part away from the other to ease the propagation of the nuclear split; chopping at initial application of power as the tip of the phaco is being buried in the nucleus; and angling the phaco probe throughout sub-chops so that nucleus rotation can be lessened.
Moreover, femtosecond lasers can now divide the cataract nucleus into segments, and this technique can reach efficient results in less time with less degree of mechanical energy. This technique has brought more effectiveness to cataract surgery as well as more enjoyment to the surgeon. Importantly, the patient benefits from a minimally invasive procedure with excellent results.
