September 2018

CATARACT

YES connect
Preparing for anterior vitrectomy


by Liz Hillman EyeWorld Senior Staff Writer

Dealing with vitreous is a part of life for every anterior segment surgeon. The most common situation necessitating an anterior vitrectomy is a ruptured posterior capsule during cataract surgery; in a split second the case can go from “great” to “complicated.” In many residencies, when the capsule is broken, an attending or fellow will take over and perform the anterior vitrectomy. As a result, many young surgeons have seen several anterior vitrectomies but have not performed the procedure themselves until they are out of training.
In this month’s “YES connect” column, John Hovanesian, MD, Charles Weber, MD, and Nicole Fram, MD, discuss their approach to planned and unplanned anterior vitrectomies. It is important for the surgical team to have the vitrectomy equipment in an easily accessible location and to know how to set it up to minimize stress and disruption during the case. By being prepared for this, and following the excellent advice in this column, young eye surgeons can succeed in these stressful cases and still achieve excellent outcomes for their patients.

David Crandall, MD,
YES connect co-editor

 


Anterior vitrector used to remove residual Soemmering’s ring near the completion of an IOL exchange following secondary IOL placement via double-needle intrascleral haptic fixation. Note the lower cut rate.
Source: Charles Weber, MD

Proper planning and practice can result in positive outcomes

There’s a saying that “the only surgeon who doesn’t have complications is the one who doesn’t operate.” It’s a saying that John Hovanesian, MD, Harvard Eye Associates, San Clemente, California, cites, especially as it applies to complications during cataract surgery that might require anterior vitrectomy.
“Every surgeon needs to have some basic vitrectomy skills in order to handle what may arise in the operating room,” Dr. Hovanesian said. “It’s a skill that we think of with a little bit of dread because of the situations where it arises, but it’s something we can’t wish away.”
The most common need for anterior vitrectomy occurs when the posterior capsule is opened, inadvertently, during cataract surgery and vitreous presents itself into the capsular bag or anterior chamber, Dr. Hovanesian said. Charles Weber, MD, EyeHealth Northwest, Portland, Oregon, and adjunct assistant professor, Moran Eye Center, University of Utah, Salt Lake City, said the most common situations to necessitate anterior vitrectomy in his practice are subluxated and dislocated lenses.
“These cases might already have vitreous presenting to the anterior segment preoperatively, vitreous presenting anteriorly intraoperatively, or a high enough risk of postoperative vitreous prolapse to necessitate vitrectomy,” Dr. Weber explained.
Nicole Fram, MD, Advanced Vision Care, Los Angeles, said that while the unplanned situations that require anterior vitrectomy are stressful, understanding the basic principles of how to handle these cases will improve patient safety and help ensure a positive result.
In any case, Dr. Hovanesian said thorough cleaning up of vitreous is necessary before implanting an IOL in order to leave the eye with a round pupil and reduce the risk of cystoid macular edema and other complications.
The first thing to do when vitreous presents itself intraoperatively is to stop and take stock of the situation, leaving in any instruments already in the eye, Dr. Hovanesian said.
“You want to have flow naturally moving from the anterior chamber to the posterior segment, so if you’ve got a phaco needle in the eye and you’ve got irrigation on, that’s usually good,” he explained. “You should leave it on until you can exit the eye. Often, putting a second instrument through a side port allows you to infuse fluid or viscoelastic before removing the phaco instrument or whatever instrument is in the main incision. That keeps the positive pressure, and it prevents unnecessary movement of vitreous forward.”

Dr. Weber said he always uses micronized triamcinolone—a 1:10 dilution with balanced salt solution —in cases where vitreous is present in the anterior chamber, or if there is enough concern that its presence or absence should be verified.
“The risk of postoperative complications secondary to unaddressed vitreous within the anterior segment requires a surgeon to rule out the presence of vitreous,” he explained.
Dr. Fram also said she routinely stains the capsule to visualize vitreous strands, using preservative-free triamcinolone diluted 1:10 with balanced salt solution. She added that she usually performs the bulk of the vitrectomy first, using a bimanual approach, then stains to identify any remaining strands.
“There are two reasons to consider the use of preservative-free triamcinolone,” Dr. Fram said. “One is diagnostic: improved visualization of vitreous strands and understanding of when the vitrectomy is complete; and two is therapeutic: often there is a prolonged surgical time and increased risk of macular edema postoperatively. Intracameral use of diluted steroid may help with postoperative rehabilitation and decrease risk of prolonged postoperative inflammation.”
While Dr. Weber finds the limbal approach is often sufficient for anterior vitrectomy, provided the tip of the vitrector is kept posterior to avoid vitreous traction anteriorly, Dr. Hovanesian said he only uses this approach if the vitreous is very minimal.
In other cases, Dr. Hovanesian prefers a pars plana approach, pulling the vitreous back to its more natural space. He said he will put fluid infusion through a limbal incision in the anterior chamber, so fluid is flowing into the eye then out of the eye through the pars plana vitrectomy port.
“You want to sweep vitreous into the back of the eye,” Dr. Hovanesian said.
Dr. Fram said she prefers to initially use a limbal approach for unplanned anterior vitrectomy during routine phaco. Only after lens fragments are removed and with adequate corneal visualization would she select a pars plana approach. For planned vitrectomy, such as in the case of repositioning an IOL, for example, she routinely uses a pars plana approach combined with a limbal approach prior to intrascleral, scleral, or iris fixation.
Dr. Fram always uses a bimanual approach to vitrectomy, keeping her settings on cut/IA. She uses the Centurion Vision System (Alcon, Fort Worth, Texas) at a 4000 cut rate, lowering the bottle height and filling the anterior chamber with viscoelastic or balanced salt solution before removing instruments from the eye to prevent chamber collapse and further vitreous prolapse.
“Each surgeon should work within his or her experience and comfort level,” Dr. Fram said.
If there is still retained lens material, Dr. Hovanesian said he prefers to remove the vitreous that’s in the way and then, inserting viscoelastic to keep the chamber full, use manual irrigation/aspiration to remove the remaining cortex. Dr. Weber said if lens fragments present during the vitrectomy, the surgeon should reduce the vitrector to a low cut rate.
Using viscoelastic to fill the anterior chamber prior to removing the phaco tip in the event of a posterior capsule tear can not only prevent further vitreous prolapse, but it can “plug” this hole to allow for safe removal of lens fragments, Dr. Fram said. These fragments should be carefully rotated out of the capsular bag and into the anterior chamber where the surgeon can convert to a small incision extracapsular approach, she said.
“Other techniques such as sheets glide placement to keep fragments from falling posteriorly or IOL scaffold have been advocated,” Dr. Fram said. “However, these strategies require complex surgical maneuvers that may not be in the comfort zone of all surgeons. A retina specialist can always perform a planned vitrectomy at a later data and remove the lens fragments in a safe manner.”
After the vitrectomy is complete and remaining lens material is removed, IOL placement depends on capsular support and the location of the capsular tear. If there is enough peripheral support (around 210 degrees), Dr. Hovanesian said there is enough to put the optic and haptics fully in the bag. But typically, he, Dr. Weber, and Dr. Fram said, provided there is a round capsulotomy, placement of a three-piece IOL in the sulcus with optic capture occurs. Dr. Hovanesian pointed out that one should take into account any power adjustments that might need to be made should the optic be placed in the sulcus. He mentioned the formula on doctor-hill.com, the website of Warren Hill, MD. Generally, the higher power the lens, the more adjustment that needs to be made, Dr. Hovanesian said.
In the absence of capsular support, Dr. Fram said an anterior chamber IOL could be used, with measurement for placement including white-to-white plus 0.5–1 mm.
“The surgeon should avoid extending the clear corneal incision and move superiorly for a fresh scleral tunnel measuring 6 mm as this will reduce iris prolapse and irregular corneal astigmatism,” Dr. Fram explained. “Acetylcholine chloride should be placed, and a mid-peripheral SPI can be made with the vitrector (100 cut rate and 700 vacuum). The ACIOL can then be placed carefully using the help of a sheets glide. Alternatively, one can perform intrascleral or scleral suture fixation, depending on surgeon experience.”
Dr. Weber performs a dilated exam of the posterior segment within the early postoperative course, but his medication instructions remain the same as an uncomplicated case. Dr. Hovanesian said he treats the patient longer with steroids and NSAIDs. Dr. Fram said she instructs patients to call if they experience extreme pain or discomfort postoperatively, as it could indicate high intraocular pressure.
The physicians said they are forthright with the patient after surgery about what happened.
Preoperatively, Dr. Hovanesian discusses the odds of complications with his patients. There is a 1 in 1,000 chance that a major complication could occur and a 1 in 100 chance for a minor but not vision-threatening complication. The situations meriting an anterior vitrectomy fall into the latter camp.
“I usually refer back to our conversation before surgery,” Dr. Hovanesian said, adding that he explains that while he tried to keep the lens capsule as intact as possible, a complication occurred that required additional steps to the cataract surgery. He tells patients, “I think you’re going to do well, but it may take longer for you to achieve that final vision than a normal person. I wish that it didn’t happen, but I’m happy with the way things turned out.”
As a final pearl of advice, Dr. Weber recommended young surgeons get to know the different vitrectomy settings and seek out videos of the various vitrectomy techniques. Dr. Fram pointed out that there are tools for practicing anterior vitrectomy with SimulEYE (Westlake Village, California).
All in all, Dr. Hovanesian said, what makes a good surgeon is how the surgeon handles the vitreous loss. “The measure of a skilled surgeon is someone who keeps their head about them and diligently pursues getting all of the vitreous, getting all the lens material, getting a round pupil, and getting the patient a good result from surgery even when things go poorly,” he said.

Editors’ note: The physicians have no financial interests related to their comments.

Contact information

Fram
: nicfram@yahoo.com
Hovanesian: drhovanesian@harvardeye.com
Weber: charles.weber@gmail.com

Preparing for anterior vitrectomy Preparing for anterior vitrectomy
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