Cataract surgeons weigh-in on how to handle a dropped nucleus

No surgeon wants to face a cataract removal gone wrong, but according to cataract surgeons interviewed by Ocular Surgery News, preparing for the possibility of a dropped nucleus with prolapsing vitreous is a must.

A handful of techniques have been developed for the management of a dropped nucleus; although they differ in execution, they can help the cataract surgeon rescue a cataract extraction gone amiss.

These techniques differ not only in the particular cases they are appropriate for and in the instruments they employ, but also in their emphasis on surgical management. They share a commonality in recognizing that a ruptured posterior capsule leading to a dropped nucleus and anteriorly displaced vitreous is a dangerous situation. But surgeons diverge on the idea of the most advantageous approach for clearing the anterior vitreous.

According to David F. Chang, MD, an OSN Cataract Surgery Board Member, the management of a descending nucleus requires the surgeon to be ready to recognize and react.

David F. Chang, MD, suggests using a dispersive OVD and manually levitating nucleus fragments into the anterior chamber. Image: Vaccaro B

“These are strategies, like any techniques, that have to be mastered and must be within the skill set of the surgeon; they’re not something that everyone will feel comfortable doing, and there is no shame in referring the patient to the retina specialist to remove retained nucleus. By the same token, if a surgeon is comfortable with these maneuvers, it’s an option,” he said.

Ruptured posterior capsule

Before dealing with capsular rupture and vitreous loss, however, the surgeon must first recognize that the case has gone awry, according to Rosa Braga-Mele, MD, FRCSC, OSN Cataract Surgery Section Editor. A sudden shallowing or deepening of the anterior chamber, or a contraction of the iris or pupil, may be a tip-off that the posterior capsule has ruptured, and a suddenly clogged phaco tip may indicate prolapsed vitreous.

At this point, it behooves the surgeon to have prepared before starting surgery. This means assembling the equipment that might be needed and knowing rescue techniques, but also rehearsing mentally for when a surgical case might go wrong.

Rosa Braga-Mele

“You want to recognize and react appropriately, but you don’t want to panic,” Dr. Braga-Mele said.

The inclination may be to immediately withdraw the phaco tip in the context of a ruptured posterior capsule in order to go after the falling nucleus or fragments. Such a move, though, risks collapsing the anterior chamber, and “whatever fragments were going are going to go further south, more vitreous is going to come forward and you’ve lost any control over the case,” Dr. Braga-Mele said.

Instead, the second instrument hand is removed, a dispersive ophthalmic viscosurgical device (OVD) is inserted in the eye, and the phaco tip is removed only after the anterior chamber is stabilized.

Lens in the anterior vitreous

After the anterior chamber is stabilized, the next step is to assess if the nucleus has dropped from the bag, and if it has, where it has stopped its descent. Gravity will naturally draw the nucleus toward the retina, but the interspersed vitreous will act as a barrier. However, as vitreous liquefies in aged patients, some patients may be more susceptible to complete nucleus drop to the retinal surface.

According to Dr. Braga-Mele, nuclei dropped to the middle or posterior vitreous may be beyond the point of retrieval. In that case, closing and referring may be the safest alternative.

“I would do a good bimanual anterior vitrectomy, clean it up, assess the integrity of the anterior capsule, and if the anterior capsule is intact and you’ve got an intact continuous anterior capsulorrhexis, I would then put a lens in the sulcus and perhaps even fixate the optic within the anterior capsulorrhexis,” Dr. Braga-Mele said. “At this point, with nuclear segments going back, I would refer to a retinal specialist.”

Nuclei that have fallen only to the anterior vitreous, however, may be salvaged. Using a technique popularized by Charles D. Kelman, MD, the surgeon can levitate the nucleus or fragments back to the anterior chamber, where they can be removed with modified phacoemulsification or manual extraction techniques.

In the posterior-assisted levitation (PAL) technique attributed to Dr. Kelman, a metal spatula is inserted through a pars plana incision, and the nucleus fragments are carefully manipulated anteriorly and back through the iris plane. A variation of PAL was described in 2004 by Lal and colleagues and is known as the chopstick technique.

In the chopstick technique, a Sinskey hook is inserted through a pars plana incision and below the nucleus, while a second Sinskey hook is pressed downward from the anterior chamber. With the lens or fragment pinched between the two instruments, the lens is brought forward and removed through an enlarged incision.

A third option, described by Dr. Chang and Richard B. Packard, MD, is to use a combination of dispersive OVD and manual manipulation to levitate the fragments into the anterior chamber.

“With a partially descended nuclear fragment, the surgeon may be tempted to aspirate the piece with the phaco tip because it appears quite accessible,” Dr. Chang explained. “The problem is that in the absence of the posterior capsule, you may inadvertently aspirate vitreous, and the coaxial infusion will likely propel the piece posteriorly before it can be captured with the phaco tip.”

In the so-called “Viscoat PAL” technique, the first step is to prevent the nucleus from sinking further. After a pars plana sclerotomy is made 3.5 mm behind the limbus with a disposable MVR blade, the Viscoat (chondroitin sulfate, sodium hyaluronate, Alcon) cannula is inserted to inject a small amount of OVD behind the partially descended fragment, where it can provide a safety net.

“The PAL method provides the proper angle of approach for getting both OVD and the cannula tip behind the nucleus,” Dr. Chang said.

He recommended then using the OVD cannula tip to prop the nucleus up into the anterior chamber under direct visualization.

“The surgeon has the useful option of injecting additional amounts of dispersive OVD to steer or maneuver the fragment into the optimal position for the levitating cannula,” he said.

“Injecting OVD through the phaco incision is sometimes an option, but this may be too steep an angle to approach a laterally and posteriorly displaced nucleus through a small pupil or capsulorrhexis,” Dr. Chang said. “The pars plana sclerotomy can be performed under topical anesthesia, and it can be used for the anterior vitrectomy as well.”

Anterior vitrectomy

A rupture of the posterior capsule increases the chance for vitreous to rush forward into the anterior segment. Most surgeons agree that vitreous has to be removed before lens removal, although the timing of the anterior vitrectomy can differ between techniques.

In the initial case report describing the chopstick technique, the lens was manually extracted through an enlarged incision before removing the anterior vitreous. The authors subsequently rationalized this decision, saying that “if vitrectomy is done before stabilizing and removing the hanging nucleus, there is a chance that the nucleus will drop into the vitreous cavity completely, necessitating intervention in the posterior segment.”

Dr. Chang recommended converting to a large-incision manual extracapsular cataract extraction with a lens loop when there is a sizable nucleus and a torn posterior capsule. Because there is no aspirating instrument, the anterior vitrectomy is performed after nuclear removal in that situation.

“For smaller nuclear fragments, epinucleus and cortex, you cannot continue phaco or irrigation and aspiration once vitreous has prolapsed into the working space,” he said. However, performing a thorough anterior vitrectomy at this point causes the remaining lens material to sink as the supporting vitreous is replaced with balanced salt solution.

To avoid this problem, Dr. Chang developed what he calls the “Viscoat Trap” technique. The loose residual lens material is first elevated up toward the cornea and preferably over the iris as the entire anterior chamber is filled with a dispersive OVD.

“A dispersive OVD, such as Viscoat, is more resistant to aspiration, so it will trap the pieces in the anterior chamber while you are performing the anterior vitrectomy,” Dr. Chang said.

Important in the Viscoat Trap technique, according to Dr. Chang, is to use the pars plana sclerotomy for the vitrectomy cutter.

“The trouble with using the phaco incision is that it is too large, it will leak, you will continue to pull more vitreous forward, and the supporting OVD will burp out as well,” he said. For infusion, a self-retaining irrigation cannula is placed through an oblique limbal paracentesis.

According to Dr. Chang, the pars plana approach is anatomically preferable because the incision is properly sized and the OVD-filled anterior chamber is not disturbed.

“The advantage of the pars plana sclerotomy is that you can keep the cutter tip behind the pupil at all times as you perform a thorough anterior vitrectomy under direct visualization,” he said. “Having the optimal angle of approach, you can sever all transpupillary bands of prolapsing vitreous without having to do any aspiration within the anterior chamber. Meanwhile, the lens material is supported by the dispersive OVD and remains immobile the entire time.”

After the anterior vitrectomy, Dr. Chang then goes back to aspirate the OVD-trapped lens material, knowing that it can be done without creating vitreous traction. With a posterior capsular defect, a trimmed Sheet’s glide can be used for phaco. Dr. Chang said he prefers bimanual I&A instrumentation for cortex and epinucleus.

Additional pearls

While Dr. Chang is an advocate of using the pars plana approach for anterior vitrectomy – particularly if the pars plana sclerotomy has already been created for the Viscoat PAL – other surgeons suggest that the vitrector approach is more a matter of personal comfort with the technique.

“You always do a better cleanup pulling vitreous back then you do pulling vitreous forward,” Dr. Braga-Mele said. “But if you feel uncomfortable doing a pars plana approach, what is very important is that if you do an anterior vitrectomy, you do not go through your main wound.”

An option may be to open two new limbal incisions, in which case the new opening is cut specifically for the vitrector, and the potential for additional vitreous prolapse is minimized.

“You can do a true anterior vitrectomy with an anterior approach, but through two new limbal wounds, avoiding your original wound at all costs,” Dr. Braga-Mele said.

A 2006 Back to Basics column for Ocular Surgery News by Uday Devgan, MD, FACS, described the pars plana as more physiologic, “as it will draw the prolapsed vitreous posterior where it belongs.” When the vitrector is introduced through a limbal incision – which he described as a paracentesis anterior vitrectomy – “care must be taken to avoid drawing the vitreous into the anterior chamber,” Dr. Devgan wrote.

Uday Devgan

Dr. Chang said that he is not advocating a posterior vitrectomy through a pars plana incision.

“Regardless of which incision we use, we are still removing the anterior vitreous by keeping the vitrectomy cutting tip behind the pupil under direct visualization, and we are still using a separate infusion cannula through the limbus,” he said. “The only difference is making the pars plana sclerotomy, which does not have be as snug as with a three-port posterior vitrectomy because we do not use positive pressure infusion. I think that is a under-utilized option.”

To aid in visualization of the vitreous, Dr. Devgan, OSN SuperSite Section Editor, also advocated staining it with diluted preservative-free triamcinolone. Currently, Alcon and Allergan both offer preservative-free triamcinolone; however, at the time of his original article, this was not available. He described his technique for washing the preservative from triamcinolone for staining vitreous:

“Draw 1 cc of triamcinolone (10 mg/cc) into a syringe, then attach a micro-filter and push the plunger to discard the solvent and trap the triamcinolone particles in the filter.

“Now, re-suspend the triamcinolone particles by drawing up 2 cc of sterile balanced salt solution through the micro-filter. These steps can be repeated for further washing. Then the filter can be removed and a 25- or 27-gauge cannula can be attached, and the resultant triamcinolone suspension (now 5 mg/cc and preservative-free) can be injected via the paracentesis to stain the vitreous.”

A final crucial element in anterior vitrectomy, according to both Drs. Devgan and Braga-Mele, is to employ bimanual vitrectomy, thus splitting the vitrector and irrigation. Irrigating the vitreous liquefies the medium, making it less stable and less able to support remaining lens fragments. In addition, if a coaxial I&A device is used, a countercurrent is created that pushes vitreous backward, as well as potentially propelling lens fragments backward, while aspiration works to bring it forward.

Removal of the lens

Once the anterior chamber is cleared of prolapsed vitreous, the remaining lens fragments must be dealt with. According to Dr. Braga-Mele, a Sheet’s glide can be used to stop any further vitreous prolapse and to stop lens fragments from dropping – functioning, in essence, as an artificial posterior capsule.

“I would, at this point, lower my flow and vacuum and bottle height, and proceed with phaco at a slow rate and with small, little pieces if I felt I was in a controlled situation,” Dr. Braga-Mele said.

For dense cataracts, for larger pieces or for situations in which phaco might cause turbulence or subsequent nucleus drop, manual removal of pieces may be necessary.

“If I felt I had just a couple of pieces left and I felt that phaco would only push the pieces back, I would consider opening the wound and even doing a manual expression of those couple of pieces,” Dr. Braga-Mele said.

Once the cataract is removed, it is still possible to implant an IOL, although the choice of lens is important.

“I would recommend a three-piece IOL in the sulcus, preferably with a large, rounded anterior edge optic, and if you can capture the optic within the anterior capsule so the haptics are in the sulcus and the optics are in the anterior capsule, I would do that,” she said. “Never implant a single-piece IOL in the sulcus.”

Fully descended nuclei

Both PAL techniques and the chopstick technique assume that the lens or fragment has fallen only to the level of the anterior vitreous. Whichever retrieval technique is used, the goal is to minimize compounding an already complicated situation. To that end, according to Dr. Devgan, simply acknowledging the complication and cleaning up the surgical field before referring the case may sometimes be the most appropriate course of action.

“One of the best techniques is sometimes: Let the nucleus drop, clean up the vitreous from the anterior segment, place the IOL, and send the patient to your retina colleague for a proper pars plana lensectomy,” he said. “I don’t like ‘fishing’ in the vitreous.”

Amar Agarwal

The extent of what drops to the vitreous may be a determining factor in the rescue technique employed. According to Amar Agarwal, MS, FRCS, FRCOphth, and OSN Europe/Asia-Pacific Edition Board Member, small lens fragments or cortex may be managed without additional surgical intervention.

“Patients with small cortex dropped in vitreous can have minimal vitritis, which can be controlled with steroids. Topical and systemic steroids with anti-inflammatory agents can be used, and pseudophakic cystoid macular can be minimized,” Prof. Agarwal said.

For patients with a complete drop of the nucleus to the retinal surface, Prof. Agarwal said that the anterior segment surgeon should immediately convert to a complete posterior vitrectomy using what he calls the “FAVIT” technique — FAVIT for “fallen vitreous,” as the name describes a method to remove lens fragments that have “fallen” into the “vitreous.”

If the anterior segment surgeon is not familiar with posterior segment techniques, it is preferable to refer the case, Prof. Agarwal said, but delay in management could have detrimental effects.

“The nucleus drop can be managed immediately by converting it into posterior vitrectomy and FAVIT. Delay in management can cause macular edema, vitritis, etc., which will affect the final visual outcome. Hence, early intervention is better,” he said. “The FAVIT technique has a simple learning curve, and any anterior segment surgeon can perform it with training.”

In the FAVIT technique, a chandelier illumination system is coupled to the infusion cannula to achieve visualization of the posterior segment, and an endo-illuminator is inserted through a second port. The vitrector is used in a third port — all ports are through the pars plana — to achieve complete vitreous removal. Complete vitrectomy is done around the nucleus until it moves freely. Then, the vitrectomy probe is replaced with the sleeveless phaco probe with a 700-µm phaco needle. Suction-only mode is used on the phaco probe to lift the lens off the retina and hold it while it is repositioned into the anterior chamber, where phaco or an enlarged limbal incision is used to remove the lens. If the nucleus is hard, the surgeon should extend the incision so that endothelial damage is prevented. Alternately, perfluorocarbon liquids can be injected after vitrectomy to raise the lens off the retina, and they are later removed with the phaco needle. – by Bryan Bechtel

In the case of a completely descended nucleus, should the cataract surgeon implant an IOL before referring the case to a retinal surgeon? Why or why not?

References:

• Agarwal A. Technique helps remove lens fragments that have fallen into the vitreous. Ocular Surgery News. 2006;24(9):93.
• Chang DF. Managing the broken posterior capsule. In: Colvard DM, ed. Achieving Excellence in Cataract Surgery. Thorofare, NJ: SLACK Incorporated; 2009.
• Chang DF, Packard RB. Posterior assisted levitation for nucleus retrieval using Viscoat after posterior capsule rupture. J Cataract Refract Surg. 2003;29(10):1860-1865.
• Devgan U. How to perform an anterior vitrectomy. Ocular Surgery News. 2006;24(16):77.
• Lal H, Sethi A, Bageja S, Popli J. Chopstick technique for nucleus removal in an impending dropped nucleus. J Cataract Refract Surg. 2004;30(9):1835-1839.
• Liu DR, Lee VY, Chan WM, Lam DS. Chopstick technique for nucleus removal in an impending dropped nucleus. J Cataract Refract Surg. 2005;31(9):1685.

• Amar Agarwal, MS, FRCS, FRCOphth, can be reached at Dr. Agarwal’s Eye Hospital, 19 Cathedral Road, Chennai 600 086, India; fax: 91-44-28115871; e-mail: dragarwal@vsnl.com.
• 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; e-mail: rbragamele@rogers.com.
• David F. Chang, MD, can be reached at Altos Eye Physicians, 762 Altos Oaks Drive, Suite 1, Los Altos, CA 94024; 650-948-9123; e-mail: dceye@earthlink.net.
• Uday Devgan, MD, FACS, can be reached at Maloney Vision Institute, 19021 Wilshire Blvd. #900, Los Angeles, CA 90024; 310-208-3937; fax: 310-208-0169; e-mail: devgan@ucla.edu.