Surgeons should learn variety of nucleofractis techniques
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In modern-day phaco surgery, we break the lens nucleus into smaller pieces before using the phaco probe to ultrasonically emulsify the cataract.
There are multiple different techniques of splitting the nucleus into smaller pieces, also called nucleofractis, and each has its advantages and downsides. Surgeons should be able to use all of the various techniques in order to tailor the surgery to the individual patient.
The original phaco techniques were one-handed, in which the phaco probe was used to bowl out the nucleus. There was no attempt to divide the nucleus into smaller fragments, and a large amount of ultrasonic energy was required to remove the cataract. This inefficient and cumbersome technique has largely been abandoned by the majority of cataract surgeons in favor of nucleofractis techniques.
Divide and conquer
In divide and conquer, the phaco probe is used to sculpt two grooves or trenches in the nucleus. These grooves are usually 80% or more depth, and they are created about 90° away from each other. The second instrument can then be placed into these grooves to split the nucleus into halves and then quadrants. By sculpting these grooves, the nucleus gets debulked, and instead of having four quadrants with 25% volume each, these quadrants are more like 20% volume each (Figure 1). This can make it easier to remove the quadrants through a smaller capsulorrhexis.
Source: Uday Devgan, MD
While divide and conquer does require more energy than other techniques, there is one advantage that makes this technique easier for novice surgeons: There is virtually no time constraint. A surgeon can take as long as is needed to create the grooves and then split the nucleus into quadrants. There is no finite window of time in which this must be accomplished. However, due to the inherent inefficiency of divide and conquer, most surgeons tend to graduate away from this technique shortly after learning it.
Stop and chop
The stop and chop technique blends the divide and conquer technique with the phaco chop technique. A groove is sculpted into the nucleus to create two halves, and then each half can be further sub-chopped and split into smaller fragments before being emulsified. By combining these two techniques, stop and chop makes it easier to learn chopping. Each nuclear half is about 45% of the nucleus because the initial groove debulked the central zone of the cataract (Figure 2). Also, the phaco probe can be placed deep within the groove to get a strong purchase on each hemi-nucleus in order to facilitate chopping.
The phaco machine must be programmed with two settings, one to create the groove using lower vacuum and one to chop each half using higher vacuum. While there is no time constraint for the initial groove and division into two halves, the sub-chopping technique will introduce the concept of a small window of time in which to accomplish the chop. When the phaco probe is embedded into a nucleus piece with the intent of holding it securely while the other hand performs a chop, there is a small window of a few seconds in which this must be accomplished.
Phaco chop
Since its introduction more than 20 years ago, phaco chop has been lauded as the most efficient and elegant method of nucleofractis. It is my preferred technique, and it allows an experienced surgeon to quickly and efficiently remove the lens nucleus with a minimal amount of ultrasonic energy. The primary challenge, however, is that each chop must be accomplished in a short window of time (Figure 3). Once the phaco probe enters the nucleus and the vacuum level builds up to hold it securely, there is a small window of just 1 or 2 seconds in which to accomplish the chop. If too much time is taken, then the vacuum level tends to drop, and the nucleus purchase is lost.
If a surgeon can master phaco chop, cataract surgery becomes more efficient and even safer. I encourage all surgeons to learn this technique while still keeping the skills for the other nucleofractis techniques.
There is no right or wrong way to perform nucleofractis, and I encourage all surgeons to learn each of these techniques. There are also other methods such as the pre-chop technique or femtosecond laser-assisted lens division, which can also be used to subdivide the nucleus before emulsifying it. Great surgeons may have a favorite tool in the toolbox, but they know that the best option is to have a wide variety of tools available to be able to address a wide range of surgical challenges.
See full video of this topic at cataractcoach.com.
- For more information:
- Uday Devgan, MD, is in private practice at Devgan Eye Surgery and partner at Specialty Surgical Center in Beverly Hills. He can be reached at 11600 Wilshire Blvd. #200, Los Angeles, CA 90025; email: devgan@gmail.com; website: www.CataractCoach.com.
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