Bimanual microincision phaco has advantages in safety, efficiency versus ultra-small coaxial phaco

February 1, 2007
Lynda Charters

Investigators are eagerly comparing ways to perform phacoemulsification to obtain the best results for patients. Bimanual microincision phaco has been receiving a great deal of attention and is being compared with ultra-small-incision coaxial phaco and with conventional phaco.

Comparing

"At the beginning of this century, the introduction of ultra-small technology allowed the microincisional cataract surgery to be performed," said Alessandro Franchini, MD, assistant director, University of Florence Eye Institute, Florence, Italy. "Over the past year, the introduction of the microsleeve allowed surgeons the possibility to perform coaxial phacoemulsification through a small incision.

Now that surgeons are investigating the possibility of performing the surgery with coaxial phaco through a small incision, the bimanual procedure no longer may be needed, he noted.

"The first point concerns the fluidics," he said. "During coaxial phacoemulsification, a portion of the irrigation fluid is captured by irrigation immediately after it flows out of the sleeve. Having the irrigation so close to the aspiration means that the nuclear fragments can be pushed away. So having the irrigation in one end and the aspiration in another end means that there is an increase in followability."

The second consideration, having separate irrigation and aspiration, allows surgeons to use the irrigating fluid like a surgical tool, Dr. Franchini said.

"This is one of the most important reasons that the open-end irrigation has come back into fashion," he said.

"When using the irrigation fluid, it is possible to flush the nuclear fragments from the angle, and it is possible to push up the posterior capsule and work safely inside the bag," he added. "This use of the irrigating fluid is especially useful in complex cases in patients with small pupils, for example, and in those with limited zonular dialysis."

The increasing temperature of the ultrasound tip is another consideration, he said, adding that his study showed that, regardless of the parameters of the system used, the bimanual procedure results in a smaller increase in the temperature of the tip.

"The most important factor, in my opinion, is that the sleeveless technique results in less heat at the incision site," Dr. Franchini said. "This is particularly important in microincisional coaxial phacoemulsification, because the sleeve is more rigid than the sleeve in a standard coaxial phacoemulsification procedure and there is no leakage from the incision."

An initial comparison of the two techniques in a small number of patients showed that the endothelial cell density loss, the effective phaco time, the increase in the stromal thickness, and the early recovery of visual acuity did not differ significantly between the procedures, he said. Twenty patients per group have gone beyond the 1-year follow-up, Dr. Franchini said.

"Bimanual microincision phacoemulsification has some advantages in terms of safety and efficiency compared with the ultra-small-incision coaxial phacoemulsification, especially in cases that are complex," Dr. Franchini concluded. "However, both of these procedures should be part of every surgeon's experience."

Another study

In separate research, Liwei Ma, MD, PhD, and colleagues at the Fourth Affiliated Hospital of China Medical University, Shenyang City, studied two groups of patients, one of which underwent bimanual microincision surgery and the other of which underwent conventional phaco. Each group contained 15 patients with a nuclear density of grade 3.

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