Surgeons offer ways to minimize endothelial damage during phaco

Using viscoelastic devices, controlling ultrasound power can help protect the endothelial layer.

Most surgeons would agree that viscoelastic agents and manipulation of ultrasound power are two important approaches to protect the endothelium and minimize damage during phacoemulsification.

There are several ways that phaco can damage the endothelial layer, including the delivery of total and peak ultrasound energy, the fluid volume that passes through the eye, the proximity of ultrasound to the endothelium, particle chatter, nuclear fragmentation, direct trauma by an instrument or irrigation, and prolonged surgery.

Ocular Surgery News asked several surgeons how they approach their phaco cases in regards to protecting the endothelium.

Viscoelastics

Louis D. Nichamin

OSN Cataract Surgery Board Member Louis D. “Skip” Nichamin,MD, said it is important to use an appropriate viscoelastic to minimize endothelial cell loss during cataract surgery. In cases of Fuchs’ endothelial dystrophy or particularly dense cataracts with shallow anterior chambers, Dr. Nichamin recommended using more than one viscoelastic, a dispersive to protect the endothelium and a cohesive to create space.

“I personally make frequent use of Healon5 (2.3% sodium hyaluronate, Advanced Medical Optics) to both protect the endothelium and optimize intraocular working space,” he said.

If there is no sign of endothelial damage before surgery, OSN Cataract Surgery Section Editor Rosa Braga-Mele, MD, FRCSC, said she uses Healon GV (sodium hyaluronate 1.4%, AMO), a high-molecular-weight cohesive ophthalmic viscosurgical device that she calls the gold standard.

Rosa Braga-Mele

“However, if I find that I really want to protect the corneal endothelium, then I’ll use something like Healon D (AMO) or Viscoat (chondroitin sulfate, sodium hyaluronate, Alcon), which is a dispersive viscoelastic that will coat the endothelium and protect it,” she said.

OSN Cataract Surgery Board Member Elizabeth A. Davis, MD, FACS, said she prefers a dispersive viscoelastic such as Amvisc Plus (sodium hyaluronate, Bausch & Lomb).

“The same properties that lead to good cellular protection also lead to good retention within the eye during surgery,” Dr. Davis said.

Manipulating power

Ultrasound energy can be a primary cause of endothelial cell damage in phaco.

Elizabeth A. Davis

Dr. Davis said she uses a supracapsular iris-plane approach with high vacuum to remove all but the densest cataracts, with minimal to no energy. Using the Stellaris vision enhancement system (Bausch & Lomb), she engages high vacuum, up to 600 mm Hg, to prevent chatter by maintaining nuclear particles at the phaco tip.

Options on other phaco platforms are helpful as well, Dr. Braga-Mele said. For example, transversal phaco is offered with the Ellips transversal ultrasound on the WhiteStar Signature system (AMO), and torsional phaco is offered with the Ozil torsional handpiece on the Infiniti vision system (Alcon).

“I recommend an extremely efficient phacoemulsification device that reduces energy into the eye,” OSN Cornea/External Disease Section Editor Eric D. Donnenfeld, MD, FACS, said. “The new machines by Alcon, AMO and Bausch & Lomb are all significantly more efficient than previous generation phacoemulsification devices. I use the AMO Signature, and in cases of Fuchs’ dystrophy, I will reduce the pulse duty cycle and increase the vacuum to remove the lens with minimal energy expenditure.”

Quieting turbulence

Dr. Braga-Mele maximizes power modulations to minimize phaco power, using the waveform capabilities and custom-control software of the Stellaris system, which she said is unmatched. With this system, fluidic control minimizes turbulence within the anterior segment and facilitates the ability to perform 1.8-mm microcoaxial microincision surgery with an extremely stable chamber.

“It’s the turbulence causing the nuclear material to hit the endothelium or a lot of fluid going across the endothelium that can cause more endothelial damage,” she said, noting that it is important to minimize that friction.

Dr. Nichamin said it is important for surgeons to create precise wound incisions to minimize unnecessary wound leakage, which lessens the amount of fluid turnover in the anterior chamber.

“A quieter chamber decreases turbulence and potential for trauma to the corneal endothelium,” he said.

“By coupling all of that with modern nuclear disassembly techniques that take place down more at the iris plane or within the capsular bag, we keep the traumatic element away from the corneal endothelium,” Dr. Nichamin said.

One surgeon’s approach

Almost every aspect of cataract surgery can be optimized to reduce endothelial cell loss, Dr. Donnenfeld said.

Eric D. Donnenfeld

“To start, I usually make a limbal incision for my phaco wound. In cases of Fuchs’ dystrophy, I make a scleral tunnel incision to push the incision back further from the cornea. I use a dispersive viscoelastic such as Viscoat or Healon D, which stays in the eye during phacoemulsification,” he said.

In particularly difficult cases, Dr. Donnenfeld reapplies the dispersive viscoelastic as needed, making certain to achieve the best visualization of the lens possible and using hooks or rings if visualization is not sufficient. All cataract cases are pretreated with an NSAID for 3 days.

“I find a chopping technique to be more efficient than a four-quadrant splitting technique, and I will try [to] phaco as much as possible with a bevel down,” he said.

In addition, Dr. Donnenfeld said he adds four drops of Durezol every 15 minutes (0.05% difluprednate ophthalmic emulsion, Sirion Therapeutics) immediately before surgery and three drops every 15 minutes after the procedure to protect the endothelium and achieve a clear, compact cornea postoperatively. - by Pat Nale

Click here to view the 2009 Guide to Phacoemulsifiers.

• Rosa Braga-Mele, MD, FRCSC, can be reached at University of Toronto, 245 Danforth Ave., Suite 200, Toronto, Ontario, Canada M4K 1N2; 416-462-0393; fax: 416-462-3612; e-mail: rbragamele@rogers.com. Dr. Braga-Mele is a consultant for AMO, Alcon and Bausch & Lomb.
• Elizabeth A. Davis, MD, FACS, can be reached at Minnesota Eye Consultants, 9801 DuPont Ave. S., Suite 200, Bloomington, MN 55431; 952-567-6067; fax: 952-960-0055; e-mail: eadavis@mneye.com. Dr. Davis is a consultant for Bausch & Lomb.
• Eric D. Donnenfeld, MD, FACS, can be reached at Ophthalmic Consultants of Long Island, 2000 North Village Ave., Rockville Centre, NY 11570; 516-766-2519; e-mail: eddoph@aol.com. Dr. Donnenfeld is a consultant for Alcon, AMO and Bausch & Lomb.
• Louis D. “Skip” Nichamin, MD, can be reached at Laurel Eye Clinic, 50 Waterford Pike, Brookville, PA 15825; 814-849-8344; fax: 814-849-7130; e-mail: nichamin@laureleye.com. Dr. Nichamin is a medical monitor for Bausch & Lomb.