Horizontal chop with a flip useful for dense cataract
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Horizontal chopping is my preferred phaco technique because it works well for any density of nucleus, independent of pupil size.
In this technique, the fundamentals of which are described here and here, the surgeon eliminates sculpting and uses mechanical force to cleave the nucleus. This reduces phaco power delivery in the eye and, if performed well, also reduces the operative stress on the zonules by confining the forces of segmentation to within the capsule, rather than relying on the zonules for support.
For horizontal chopping, I prefer the constant holding force of Venturi vacuum, which does not fluctuate based on occlusion. When combined with transverse ultrasound, high Venturi vacuum transfers energy to the nuclear fragment, reducing total ultrasound power and limiting tension on the zonules. With the Veritas vision system (Johnson & Johnson Vision), I can use vacuum levels of 500 mm Hg or greater while maintaining good chamber stability. The stability is augmented by the narrower diameter and lower compliance of the inner tubing and by advanced gas-pressurized infusion, which activates only during aspiration, deepening the chamber and nicely compensating for any leaky incisions.
I find a phaco flip modification useful when the lens is so dense that it has formed a leathery posterior plate. The lens has been chopped and centrally debulked, and it becomes clear that the leathery plate is a barrier to segmentation. Place the tip of the needle against the quadrant opposite the incision, and apply high vacuum and power to impale. This creates a hole that conforms to the needle tip, allowing the tip to become a manipulation tool. Maintain vacuum in foot pedal position 2, and pull the needle centrally and up. This moves the distal quadrant centrally and anteriorly. Simultaneously, gently depress the proximal quadrant with the chopper. This motion elevates the distal nucleus out of the capsule, while the chopper keeps the proximal nucleus depressed and in the capsule. Advancing the chopper forward as the nucleus tilts will continue the flipping of the nucleus. Keep the flip going until the nucleus is vertical, staying in foot pedal position 2 to maintain your vacuum grip on the distal aspect of the nucleus during this process.
As the nucleus goes past the vertical position, release the vacuum but maintain the position of the chopper. Continue to advance the chopper forward against the lower section of the vertical nucleus, and use the needle to gently push the upper section down. This action should completely invert the nucleus, and the leathery posterior plate is now anteriorly exposed, where it can be directly chopped and emulsified.
It is important to use blunt or rounded instruments when flipping a dense cataract to avoid engaging the capsule with a sharp edge. I use instruments designed specifically with safety in mind: the Dewey horizontal femto chopper (Katena) and the Packard-Dewey radius tip (MicroSurgical Technology).
This technique, combined with good technology, can help you to remove even the densest nuclei with lower than expected phaco power and little trauma to the eye.
- For more information:
- Steven H. Dewey, MD, can be reached at Colorado Springs Eye Clinic, 2770 N. Union Blvd., Suite 200, Colorado Springs, CO 80909; email: deweys@prodigy.net.
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