San Diego-Cold ultrasound technology [WhiteStar, Advanced Medical Optics Inc. (AMO)] allows the efficient removal of all densities of cataracts and is as safe as a pulsed laser microincision phacoemulsification system. A major advantage of the cold ultrasound system is that it dramatically reduces the phacoemulsification time compared with laser phacoemulsification.
"With both systems, it is possible to perform microincision cataract surgery because the temperature of the tip increases very little, and it is possible to work without the sleeve over the tip of the instrument," said Alessandro Franchini, MD, assistant director, University of Florence Eye Institute, Florence, Italy. "With both machines, it is possible to perform the surgery through two 1.1-mm incisions, and because of this, new instruments-new blades, capsulorhexis forceps, and an irrigating chopper -have had to be designed to work through such small incisions."
He and his colleagues compared the results obtained with the WhiteStar cold ultrasound system with those from the Phaco- Lase (Asclepion-Meditec Co.). Eighty-six patients underwent cataract extraction with the cold ultrasound system and 274 with the laser phacoemulsification system.
Time comparison However, the investigators found an important difference between the two instruments in the effective phacoemulsification time.
"When the laser was used to remove cataracts . . . with a density of 1, the effective phacoemulsification time was 24 seconds," Dr. Franchini reported. "In contrast, when cold ultrasound was used to remove the same-density cataract, the effective phacoemulsification time was less than 1 second. When removing the hardest 4+ cataracts, cold ultrasound required only 14 seconds compared with almost 9 minutes for the laser."
Based on these results, regarding safety, the investigators concluded that laser and cold ultrasound are equally safe instruments. Using the two methods, it is possible to achieve clear corneas on the first postoperative day and there is very little increase in the temperature of the tip, making it possible to perform a bimanual technique, Dr. Franchini explained.
"Regarding the efficiency of the technique, however, cold ultrasound technology is more efficient compared with laser. We found a significant reduction in the effective phacoemulsification time. It is possible to remove lenses of all densities through an incision of about 1 mm," he concluded.