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No-vacuum chop technique safe and effective with all types of cataract
The phaco tip drills into the nucleus. From this central position it holds and aspirates the nucleus during cracking maneuvers.
BRESCIA, Italy – A new modification of the bevel-down technique of nucleus cracking deals effectively with all types of cataract with minimal stress on the zonules and no damage to the surrounding ocular structures.
As explained by its developer, Alessandro Pezzola, MD, a surgeon in private practice here, the “no-vacuum” chop technique eliminates most drawbacks of other chopping procedures. There is no initial sculpting of a trough, which could easily produce rotation or dislocation of the cataract and requires a high ultrasound time, mainly in hard nuclei.
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Instead, the phaco tip creates a central bowl and progressively sinks into it like a drill, working at maximum efficiency in the full occlusion mode, shortening ultrasound exposure time. From this central, internal position, the remaining nucleus is held during cracking maneuvers and aspirated. No vacuum is used, to prevent surge and anterior chamber collapse.
“Statistically, we have cut down quite a lot on ultrasound time and complication rate compared to other techniques. We feel we have also gained a better control at all stages of the procedure, and that chopping is much easier and safer in this way. Also in complicated cases, with hard cataracts, weak zonules or small pupils, the procedure is extremely safe and reliable,” Dr. Pezzola said.
Drilling a central tunnel
Dr. Pezzola described his “no-vacuum” technique.
“A 6-mm capsulorrhexis and hydrodissection are performed with gentle maneuvers to prevent zonular stressing,” he said. “Then a central bowl is excavated in the nucleus with a 30° phaco tip, pointing it downwards and producing a series of short, subsequent occlusions (figure 1). The machine is set at high levels. Vacuum and power are according to nucleus hardness. Ultrasounds are delivered in the pulse mode with a frequency of 8 Hz to prevent overheating of the tip.”
The tip drills toward the center of the nucleus, progressively emulsifying and aspirating material (figure 2). The high vacuum holds the nucleus, without any traction on the zonules. At the same time, the small attraction/repulsion movements of the pulse mode prevent prolonged occlusion.
“This step-by-step deepening of the tip makes you feel more in control of the progression inside the nucleus. Once you see a red reflex appear, then you know that the tip has almost reached the posterior epinucleus layer,” Dr. Pezzola said (figure 3).
No vacuum
“Chopping is now easy, even in very hard cataracts, as there is a central bowl or crater which has broken the nucleus integrity from the inside. We are in the center of a ring-shaped cataract. The phaco tip is positioned sideways at the bottom of the bowl or crater,” he said.
No vacuum is used. This is an important advantage of the procedure, as it eliminates one of the most troublesome stages of traditional chopping techniques. Accidental occlusion breaks may in fact produce surge or anterior chamber collapse.
A chopping instrument is then inserted from the anterior cortex into the lens along the equator and pulled toward the phaco tip, cutting through the ring thickness (figure 4). The surgeon is moving only the fingers, while hand and wrist are still.
“The maneuver is repeated in different position and the nucleus is divided in six or eight segments (according to the hardness of the cataract) without a central hinge (figure 5), because the center of the nucleus has been removed,” Dr. Pezzola said.
“It’s such a relief not having to struggle with a central traction. The traditional cracking maneuvers at the center of the nucleus are one of the main causes of zonule breaking and nucleus dislocation. Another advantage is that the segments are blunt and therefore less threatening for the posterior capsule during the rotation movements of phacoemulsification.”
Aspiration is then performed, using the same machine setting of the tunnel-drilling stage (figure 6).
For Your Information:
- Alessandro Pezzola, MD, can be reached at Via S Bartolomeo 15, Brescia, 25128, Italy; (39) 030-370-0138; fax: (39) 030-370-1393; e-mail: alpez@libero.it.