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New technology minimizes phaco energy during cataract surgery
With the fluidics system of the Sovereign, more mechanical fragmentation is possible, a surgeon says.
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WEST HILLS, Calif. — The vacuum control of the Sovereign (Allergan, Irvine, Calif.) phaco system allows surgeons to minimize the energy used during the fragmentation and removal of cataracts, according to Samuel Masket, MD, here. Dr. Masket believes that “occlusion mode” phaco with this phaco unit will mean safer, more consistent results for a variety of cataracts.
The direction of cataract surgery technology is efficiency, and according to Dr. Masket, “My definition of efficiency really is more of reproducibility than one of speed.” Reproducibility, he asserts, is achieving a consistent result for each procedure despite variables in cornea condition, chamber depth, pupil size, and especially cataract density. It is for this variety of case types that Dr. Masket says the cataract surgeon needs flexibility in his approach and from his equipment.
“Occlusion mode” phacoemulsification
Before surge control, cataract surgeons encountered problems controlling vacuum flow rate and vacuum power during phacoemulsification. In particular, when material occluding the phaco tip suddenly cleared and the tip had become unoccluded, the resultant rapid vacuum surge would cause a large volume of fluids to be drawn, potentially damaging the posterior capsule and/or other anterior segment structures.
With the advent of the Diplomax (Allergan) system, surgeons were introduced to the concept of vacuum control through preprogrammed settings. According to Dr. Masket, the Sovereign phaco system’s “occlusion mode” represents the next step, wherein a digitized pump senses pressure readings at the phaco tip, and an onboard computer regulates the direction and the speed of the pump according to the surgeon’s parameters. It can detect instant pressure changes, then stop or increase the aspiration flow.
“What these advances result in is a remarkably stable chamber,” Dr. Masket said. This chamber control enables Dr. Masket to manage cataracts of varying density in the safest way possible.
Reducing energy
Dr. Masket’s “personal algorithm” for cataract surgery involves two concepts: first, reducing the amount of emulsification energy required to divide the lens by utilizing mechanical division; and second, minimizing the amount of phacoemulsification energy necessary to remove the fragments.
The stability of the anterior chamber and vacuum-assisted control of the cataract provided by the Sovereign system allows Dr. Masket to take advantage of mechanical cracking methods, such as a chop or stop-and-chop maneuver. When pupil size and cataract density permit, Dr. Masket prefers these mechanical methods because they reduce the amount of ultrasound energy required for fragmentation.
Dr. Masket pointed out that there are cataracts that are so dense that division by emulsification is necessary. In these cases, too sharp a chopper would be required, making it difficult to protect the posterior capsule. With more experience using the Sovereign system, Dr. Masket is confident he will be able to achieve a greater level of mechanical subdivision with more dense nuclei.
Vacuum-assisted phaco
When removing the fragments, Dr. Masket leaves the handpiece in the center of chamber to avoid damage to the endothelium or posterior capsule. The fluidic system causes fragments to come to the tip; however, he suggested that one also can use the nondominant hand to bring material onto the tip, where it can be emulsified in a safe position.
The cutting efficiency of the Sovereign system, according to Dr. Masket, allows him to reduce the amount of emulsification energy necessary to remove any given lens density. He uses movement of the lens as an indicator that the power is too low. According to Dr. Masket, “If you are moving the lens, you are either trying to sculpt too much or not using enough energy level. So if you’re removing tissue rather than moving tissue, you’re using enough energy.”
Given the variety of situations and conditions that may be presented to the cataract surgeon, Dr. Masket warns that one must be prepared to diverge from the straight line to removing the fragments, yet the goal is still to ultimately find oneself at a consistent endpoint. He noted, “It’s our adaptability, and the equipment adaptability that hopefully will get us there.”
For Your Information:
- Samuel Masket, MD, can be reached at 7320 Woodlake Ave., Ste. 380, West Hills, CA 91307; (818) 348-5166; fax: (818) 348-6190; e-mail: avcmasket@aol.com. Dr. Masket is a paid consultant for Allergan.
- Allergan Inc. can be reached at 2525 Dupont Drive, Irvine, CA 92612; (800) 366-6554; fax: (800) 752-7006.