1618: Why did I choose stop-and-chop?

For 22 years, I did a combination of both private practice as well as academics in which I taught the UCLA Stein Eye Institute ophthalmology residents ocular surgery. Having the two parallel practices was enjoyable, and I was fortunate to train hundreds of ophthalmologists who are now in their own practices. I recently retired from my academic duties, and now I focus solely on my private practice, but I will always remember the sage advice that I taught new ophthalmologists: Learn as many techniques as possible so that you can tailor your surgery to each specific eye.

For most cataract surgeries, I prefer a variation of phaco chop because it is safe and efficient, plus it is a pleasure to perform. However, there are certain cases in which reverting back to the technique of stop-and-chop can be helpful. In the case presented here, our patient has a small eye with a shallow anterior chamber of less than 2 mm in depth. She had a prior episode of angle-closure glaucoma that required a laser peripheral iridotomy to resolve. Her cataracts have progressed over the past few years, and she is now ready for cataract surgery.

When we look at the biometry for this case, there are some unusual values. The axial length is 20.5 mm, and the anterior chamber depth is just 1.7 mm. With keratometry values showing a steep 48 D value, the IOL calculations using the Ladas Super Formula 2.0 AI give a value of +28.5 for a plano refractive outcome. The lens thickness measures almost 5 mm anterior to posterior, and the maximum pupil dilation is about 6 mm. This is certainly going to be a challenging case because we are working in such a confined space.

If we perform phaco chop, either vertical or horizontal, we will split the nucleus into two halves, each about 50% of the total lens volume. These larger halves will need to be sub-chopped into smaller fragments before phacoemulsification. A better option in this case may be to perform stop-and-chop. This is a technique described by Paul Koch, MD, many years ago in which a central groove is sculpted and the nucleus is split into two pieces. Then the surgeon stops and proceeds to switch to the chop technique for the remainder of nucleus removal.

Figure 1. The phaco probe is used to sculpt a central groove in the nucleus to debulk it.

The advantage of sculpting the central groove is that it debulks the nucleus, particularly the dense central endonucleus (Figure 1). The central groove is about 1.5 times the width of the phaco probe, and it allows us to debulk about 20% of the cataract volume. This makes each hemi-nucleus about 40% of the total lens volume. Now each hemi-nucleus is smaller than if we performed a straight chop technique. These smaller hemi-nuclear pieces are then brought partially out of the capsular bag and chopped at the iris plane (Figure 2). The reduction of volume of each hemi-nucleus from 50% to 40% makes a significant difference, especially in this eye with a crowded anterior segment.

Figure 2. Each hemi-nucleus can then be brought partially out of the capsular bag and chopped.

After cataract removal and clean-up of the cortex, the single-piece monofocal IOL is implanted in the capsular bag. Because of the high dioptric power, a larger cartridge is required for IOL insertion, and the incision needs to be slightly widened to accommodate it. When the IOL is placed in the capsular bag (Figure 3), we can see that the 6-mm optic is nicely overlapped by the 5-mm capsulorhexis, which will hold it securely within the capsular bag.

Figure 3. The high power +28.5 D IOL is implanted in the capsular bag after slightly widening the incision to allow for the larger injector tip.

When teaching cataract surgery to ophthalmology residents, our normal progression is to start with divide-and-conquer, then move to stop-and-chop, and finally advance to variations of phaco chop. While this progression may imply that phaco chop is the best technique, the truth is that there is no right or wrong way to perform phaco. We should learn as many techniques as we can and then tailor our surgical approach to each patient and each specific eye.

I am happy to report that this patient had an outstanding outcome, achieving a refractive target of close to plano. We also resolved the issues of narrow angle and shallow anterior chamber because the 1-mm thin IOL has replaced the nearly 5-mm thick cataractous lens.

While I miss the days of literal hand-holding and intra-operative coaching with the UCLA Stein Eye Institute residents, we can teach a much wider audience of ophthalmologists with these Back to Basics columns and our surgical teaching videos on CataractCoach.com.

link here

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