Surgeon offers tips on avoiding adverse events during phaco

Using the newest machines can help avoid surge and capsular tears.

Issue: April 15, 2001

KOLOA, Hawaii — By using occlusion and taking care to limit surge, surgeons may reduce the occurrence of adverse events during phaco, said William J. Fishkind, MD.

In a presentation at Hawaii 2001, the Royal Hawaiian Eye Meeting, sponsored by Ocular Surgery News in conjunction with the New England Eye Center, Dr. Fishkind said understanding new technology is key in improving phaco.

“We need to move away from old technology and move toward new technology using occlusion now to maximize our efficiency. We are in an exciting time when it comes to phacoemulsification. It’s still the number one procedure we’re all performing, and certainly if we’re going to do this we want the proper equipment to do the job properly and therefore look at the new machines,” he said.

Posterior capsular tears

Posterior capsular tears are something a surgeon wants to avoid during phaco. In 3,693 cases, Dr. Fishkind had an incidence of 1.19% of vitrectomy.

“If we look at the timing of the tear, in my case 30 of them or 73% occurred during phaco,” he said. “So phaco is one of the most significant times that we tear the posterior capsule.”

According to Dr. Fishkind, posterior capsular tears can occur when there is a small tear in the anterior capsule that extends around the equator and into the posterior capsule during surgery. Also, surge can cause tears by allowing the capsule to collapse around the nucleus.

“In my own study, I found that surge actually caused 65% of the capsule tears,” he said. “It is my strong sense that surge is a cause of tears of the posterior capsule and it probably occurs a lot more frequently than we think it does.”

Dr. Fishkind said that by decreasing surge, posterior capsular tears would also decrease.

“We have to become aware of the issue and then we have to appropriately make changes,” he said. “Our hope is that if we decrease the amounts of surge and the severity of surge we’re going to decrease by a significant margin, probably 50%, the number of tears in the posterior capsule and the number of complications we have to deal with as phaco surgeons.”

Occlusion

According to Dr. Fishkind, prevention of surge can take place during pre-occlusion, occlusion and post-occlusion.

“We know we don’t like surge,” he said. “It’s a problem. It makes us nervous. It makes us move the surgery to the anterior chamber to stay away from the posterior capsule. It causes trauma to the anterior segment, shallowing it, tearing capsule, irritating iris and aggravating the blood-aqueous barrier. So we want to prevent it.”

One pump that Dr. Fishkind recommends is the Concentrix model used in the Millennium (Bausch & Lomb). This type of pump can be programmed to act like a peristaltic or venturi pump. It also has a setting that allows the surgeon to command vacuum level setting or flow mode by controlling rise time.

“We can prevent surge in pre-occlusion by decreasing vacuum flow using a chamber maintainer or the dual linear foot pedal of the Millennium machine,” Dr. Fishkind told meeting attendees, even though he said chamber maintainers don’t work too well.

“We can prevent surge in occlusion by using the ABS system that Alcon had developed,” he said. “Alcon’s ABS system gives us a tiny 0.175-mm hole in the shaft of the phaco needle. So when the needle occludes, fluid flows through that little tip in a varying amount and prevents the occlusion. So it prevents the surge in the occlusive phase.”

According to Dr. Fishkind, surge can be prevented in post-occlusion by changing the foot pedal yaw on the Millennium.

“At one point we use vacuum, at one point we use phaco power and we can have vacuum independent of phaco power,” he said.

“We can change surge in post occlusion by employing software in the machine, like the Allergan Diplomax or Sovereign, which uses microprocessors to prevent surge. Same with the Paradigm system and now we see the STAAR Wave has both microprocessors and the rolled tubing, all of which prevent surge in the post-occlusive phase.”

The Sovereign machine also has a threshold number where the surgeon sets the flow and power modulation.

“You can manipulate all these parameters at a couple of points in the procedure, allowing you fine control of occlusion,” Dr. Fishkind said. “The Allergan Sovereign has a digital pulse pump. If you look at it, it looks like a peristaltic pump but it is so closely controlled by computers that it can move forward to increase aspiration. It can hold it steady and it can move backwards to decrease and it can do so quickly with its direct fluid leakage by not having air in the line so accurately that it will act just like a venturi pump moving very quickly.”

For Your Information:

William J. Fishkind, MD. can be reached at 5599 N. Oracle Rd., Tucson, AZ, 85704, (520) 293-6740; fax: (520) 293-6771; e-mail: fishkin@azstarnet.com. Dr. Fishkind is a paid consultant for Allergan.