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Two experts debate use of pars plana vitrectomy in difficult phaco cases
Although both agreed that it is the preferable approach, one argued that the technique is not practical for anterior segment surgeons.
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The question of whether anterior segment surgeons should perform pars plana anterior vitrectomy before challenging phacoemulsification cases is controversial, with compelling arguments on both sides. At the Hawaiian Eye 2008 meeting, two surgeons presented the pros and cons of employing this technique.
 Rosa Braga-Mele |
According to OSN Cataract Surgery Section Editor Rosa Braga-Mele, MD, FRCSC, pars plana vitrectomy is superior to limbal vitrectomy, particularly with the emergence of 23- or 25-gauge systems that help simplify the procedure.
 Jay S. Duker |
“It makes the phaco a lot easier and makes a hard case into a simpler case,” she said. “But do be aware that patients who are highly hyperopic tend to have a lot of scleral rigidity and are at higher risk of choroidal hemorrhage.”
But OSN Retina/Vitreous Section Member Jay S. Duker, MD, argued that, although he agreed that the pars plana approach is preferable in many situations, it is not the most practical approach for anterior segment surgeons who are not accustomed to performing it.
“From a practical perspective, most anterior segment surgeons do vitrectomy uncommonly,” Dr. Duker said. “Most are not trained or comfortable with the pars plana approach. So in my mind, the positives don’t outweigh the negatives.”
“If you choose to do pars plana vitrectomy, there is a learning curve, and doing it with a mentor and practicing it in a wet lab to be comfortable with the approach is appropriate,” he said. “You must know how to at least diagnose the complications and get [patients] to a retinal specialist promptly if they occur.”
Superior to limbal vitrectomy
Dr. Braga-Mele said cases in which pars plana anterior vitrectomy may be warranted before phaco include smaller eyes, nanophthalmos, hyperopic patients, those with poor dilation and patients with glaucoma who may have an extremely shallow anterior chamber.
The procedure, in cases of capsule rupture, can be preferable to limbal vitrectomy, which involves pulling vitreous anteriorly toward the wound. Limbal vitrectomy also provides poor access to the subincisional vitreous and any remaining vitreous under the iris and could potentially damage the anterior capsule, she said.
“You tend to remove a lot more [vitreous] than you need and potentially can damage the capsule, especially the anterior capsule, which you’re really trying to keep intact because this is where you’re going to be able to place the lens,” Dr. Braga-Mele said.
“You’re never going to fully clean it up with a limbal, and it will be more difficult to have that round pupil and have a stable chamber,” she said.
Dr. Duker said he feels that it is less practical for most anterior segment surgeons who have not been trained sufficiently in the pars plana technique.
“Most training programs don’t teach pars plana vitrectomy unless you’re in a retina program,” he said.
He also argued that the goal of vitrectomy is not to minimize vitreous loss.
“I think that vitrectomy is more efficient from behind than it is from anterior,” he said. “But I will differ with one comment. This is not a ‘less is more’ situation. Remember, when retina specialists do a vitrectomy, we remove all of the vitreous. … Once you break the capsule and decide you’re going to move vitreous, the goal isn’t just to remove a little.”
Importance of wound placement
Dr. Braga-Mele said if the capsule ruptures during phaco, a pars plana incision should be made right away with a separate incision anteriorly for infusion and aspiration.
“Never go through your main phaco wound because there will be vitreous coming out through the phaco wound all the time,” she said.
Dr. Braga-Mele cited a 2003 study published by Chalam and colleagues in the Journal of Cataract & Refractive Surgery that evaluated pars plana vitrectomy management and vitreous loss during phaco.
The study found that “the small-gauge system reduced vitreous incarceration, retinal tears, hypotony, inflammation and minimal postop discomfort. [There is] quick visual recovery in these patients, so there is an advantage to it,” she said.
For his part, Dr. Duker said creating one wound instead of two offers a higher likelihood of success, with fewer complications, for anterior segment surgeons.
“Why make two wounds when one will do?” he said. “While I agree with separating the infusion from the cutter and I agree that a high cut rate is safe, I think you can clean up the anterior chamber through a limbal wound.”
Dr. Braga-Mele acknowledged that there is an increased risk of hemorrhage and other complications because of the additional incisions. To minimize the risk, she advised that surgeons should avoid the 3 o’clock and 9 o’clock long posterior segment arteries and stay at 3 mm to 3.5 mm posterior to the limbus.
Upon finishing the procedure, she instructs her patients to see a retinal specialist within 1 month.
Yet Dr. Duker said he believes that anterior segment surgeons should be equipped to deal with retinal complications of the pars plana incision themselves. Instead of referring patients to retina specialists, surgeons should be prepared to inspect the peripheral retina at the end of the case to diagnose retinal tears or detachments.
For more information:
- Rosa Braga-Mele, MD, FRCSC, is an associate professor at the University of Toronto and director of cataract unit and surgical teaching, Mt. Sinai Hospital. She can be reached at 245 Danforth Ave., Suite 200, Toronto, Canada M4K 1S2; 416-462-0393; fax: 416-462-3612; e-mail: rbragamele@rogers.com.
- Jay S. Duker, MD, can be reached at New England Eye Center, 750 Washington St., Box 450, Boston, MA 02111-1533; 617-636-4604; fax: 617-636-4866; e-mail: jduker@tufts-nemc.org.
Reference:
- Chalam KV, Gupta SK, Vinjamaram S, Shah VA. Small-gauge, sutureless pars plana vitrectomy to manage vitreous loss during phacoemulsification. J Cataract Refract Surg. 2003;29(8):1482-1486.
- Lauren Wolkoff is Executive Editor of OSN U.S. Edition.