October 2015

 

COVER FEATURE

 

Complex cataract cases

Zonular issues can complicate cataract surgery


by Michelle Dalton EyeWorld Contributing Writer

 
   
Familial ectopia lentis

Iris retractors

An example of familial ectopia lentis where the lens is not centered on the pupil and iris retractors are used to assist in the rhexis Source: Steven Safran, MD

The key here, experts say, is being vigilant about recognizing issues preoperatively and always having the right tools on hand in the OR

Zonular issuescaused by any number of conditions from pseudoexfoliation syndrome to trauma, congenital disorders (Marfan syndrome or ectopia lentis), increased age, or vitrectomy, among otherscan turn a straightforward cataract surgery into a much more complicated procedure. Sometimes, however, there is no obvious etiology and zonular deficiencies arent noticed until the patient undergoes surgery, said Bonnie An Henderson, MD, clinical professor of ophthalmology, Tufts University School of Medicine, Boston.

Agreed Robert J. Cionni, MD, medical director, The Eye Institute of Utah, Salt Lake City: In post-vitrectomized eyes there may have been some underlying pathology that was already present; because the vitreous is no longer supporting the capsular zonular IOL anatomy, it may allow for an increase in the dialysis or lens dislocation, be it the phakic or pseudophakic lens. The key to easing the potentially difficult surgery is to get the lens into position to do a safe rhexis, to stabilize the lens during rhexis and phaco, and to place the intraocular lens in the capsular bag safely while maintaining or providing support to the extent that is needed to provide centration and stability for the life expectancy of the patient, said Steve Safran, MD, in private practice, Lawrenceville, N.J.

Iqbal Ike K. Ahmed, MD, assistant professor of ophthalmology, University of Toronto, said its not a great idea to use the femtosecond laser in these patients; the capsulotomy is not as strong with the femto as with manual, and the capsule is stronger without the femto. He said that capsulotomy strength is particularly important in these cases as capsule hooks and capsular tension devices are used on the capsule edge, and if there is weakness, there is increased risk of tearing, which could not only result in serious complications but prevent the use of a capsular device to support the zonulopathy. Dr. Cionni disagreed, saying in every case of zonular compromise, my strong preference is to use the femtosecond laser. One of the toughest parts of these surgeries is achieving an appropriately sized capsulotomy centered on the lens, not the pupil and the femto helps reduce the anxiety. The added benefit of the femto is that you can decenter that capsulotomy and very precisely size it to your advantage, Dr. Cionni said.

If, however, the lens is sufficiently subluxated theres not enough real estate to use the femto properly, Dr. Ahmed said. He also recommended referring weak zonule cases if the surgeon is not comfortable performing a capsulorhexis in those cases.

Pearls for identifying zonular deficiencies

Both Drs. Safran and Cionni recommended examining the patient in an undilated state, since dilation can dampen the zonular laxity, Dr. Cionni said. Once the patient is dilated, look for a scalloped edge on the capsular bag, and get as wide a dilation as you can, he added.

If you try breaking the capsule with your forceps and start seeing capsule wrinkles, or the lens moves a bit, that can give you a subtle tip that the zonules may be weak, Dr. Ahmed said. During manual capsulorhexis, look for capsule striae, look for the capsule to move during capsulorhexis, he said.

If there is anterior chamber depth (ACD) asymmetry preoperatively, or if the eye goes out of focus constantly and you find yourself needing to focus up and down more frequently than normal during the case, this could also be a sign of weak zonules, Dr. Henderson said. Dr. Ahmed said that in addition to ACD, a posterior chamber thats deeper than normal may be a subtle sign of deficiency. Dr. Safran said hes concerned not only about what is visible, but whats not. If theres trauma and you see a 90-degree dialysis, its likely the rest of the zonules are compromised. I react more to what I feel during surgery than what I see prior, he said.

Intraoperative management

Zonular issues article summary

If the lens is mobile during the capsulorhexis, start thinking about ways to mitigate potential complications, including the use of capsule retractors and capsular tension rings (CTRs). Dr. Ahmed advised placing CTRs or capsule hooks on or around the capsulotomy if the bag is loose; in the case of a femto capsulotomy, if the capsule edge has a few areas that are weak as a result of micropunctures or misaligned laser shots, that can lead to a tear. Dr. Henderson places CTRs often, but especially if there is more than 2 clock hours of zonular dialysis. She recommended using a 3-piece IOL and places the haptic against the weak zonular area. She said a 3-piece IOLs haptics are more rigid than a 1-piece and therefore the zonular weakness is better distributed around the lens equator.

Its crucial not to stress the zonules to avoid making the dialysis worse, Dr. Safran said. Put support in before you stress the system, he advised, adding he uses capsule support such as capsule retractors early and holds off on placing a CTR until just prior to inserting the IOL. He never puts in the CTR before completing phaco and the I/A portion of the surgery. Dr. Safran prefers to use a 1-piece ZCB00 (Abbott Medical Optics, Abbott Park, Ill.) in the bag for most of these kinds of surgeries, coupled with CTR use and one or two sutured capsular tension segments (CTS). If hes opting for intrascleral haptic fixation of the IOL, he prefers the Aaren EC-3 Pal (Carl Zeiss Meditec, Jena, Germany), and has moved away from optic capture with haptics in the sulcus to using suture supported segments as needed with the lens placed in the bag. He added that he has no reservation about using toric IOLs in these cases, provided that the bag is intact and adequate suture support with a CTS is created prior to completing the case. Dr. Cionni also prefers a single- piece acrylic lens because it goes more easily through small incisions and through the capsulotomy, he said, and therefore surgeons would stress the bag less.

Every OR should have CTRs, iris hooks, and capsule retractors available, Drs. Ahmed and Cionni said. The MicroSurgical Technology (Redmond, Wash.) capsule retractor has a special double-loop design that can be placed atraumatically in the capsule bag to support the capsule equator, Dr. Ahmed said. Further, capsule retractors do not impede cortical aspiration, as might happen with a CTR.

If theres only a clock hour or so of dialysis to the lens equator, you may not need to do anything, Dr. Cionni said, but when you have a lens thats misshapen like that with only a localized area that has a scalloped edge to it, that means the area of dialysis is extremely weak, compared to the remaining zonules, and therefore, managing the case may be relatively straightforward. Placing rings too early in the surgery may lead to trapping cortex behind them, and if the dialysis is profound enough, Dr. Ahmed recommended retractors or CTSs (he invented the latter), reserving rings for cases of moderate to severe zonular deficiency. Also, the liberal use of OVDs, cannot be stressed enough, Dr. Cionni said. A complete hydrodissection, and possibly hydrodelineation, will decrease the zonular stress. Dr. Henderson advised using a chopping technique to minimize the number of times the lens must be rotated. Her preference is to place hooks after the capsulorhexis to help transform a difficult case into a manageable one.

Suturing

Always be prepared to suture the ring in these cases, even if you dont believe it will be necessary, Dr. Cionni said. Usually we can salvage the capsular bag, so the real question becomes if theres going to be a sutured CTR or CTS, he said.

If the area of dialysis is large (more than 45 clock hours) and the CTR is not sutured in place, a simple CTR will succeed in centering the IOL in the short term but eventually the entire IOL/capsular bag/CTR complex can dislocate, Dr. Henderson said.

Dr. Safran recommended suture support for the capsular bag/IOL complex be performed at the time of cataract surgery if the zonules are compromised and its likely the patient will require a secondary surgical intervention for dislocation or symptomatic pseudophacodonesis at a future date otherwise. If once the IOL is in place and the OVD removed things look stable without significant pseudophacodonesis, he may forsake suturing, especially in an older, less active patient.

I find it difficult to know exactly how many clock hours of zonules are missing or damaged because I cant always directly inspect them, so I go by how the capsular bag feels to me during rhexis formation, phacoemulsification, and the amount of stability that is present once the IOL is in place and the viscoelastic removed. If in doubt Ill lean toward adding suture support, he said.

Dr. Ahmed said if the clock hours of dialysis are superior or if the bag is very mobile, then hell suture, and he errs on the side of caution in cases of pseudoexfoliation where hes quicker to use and suture a segment. The tissue in those eyes is very poor; pseudoexfoliation affects all the zonules and its not necessarily a localized issue, he said.

Finally, these experts agreed watching patients carefully for the first month is recommended, and perhaps be a bit quicker to use a laser to disrupt anterior capsule contraction after 1 month.

Editors note: Dr. Ahmed has financial interests with Alcon (Fort Worth, Texas), Abbott Medical Optics, and Bausch + Lomb (Bridgewater, N.J.). Dr. Cionni developed the modified Cionni ring (Morcher, Stuttgart, Germany). Dr. Henderson has financial interests with Alcon, Abbott Medical Optics, and Bausch + Lomb and developed the Henderson ring (Morcher). Dr. Safran has no financial interests related to this article.

Contact information

Ahmed
: ike.ahmed@utoronto.ca
Cionni: (801) 266-2283
Henderson: BAHenderson@eyeboston.com
Safran: safran12@comcast.net

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Double trouble: Diplopia following cataract or refractive surgery by Maxine Lipner Senior EyeWorld Contributing Editor

Managing iris prolapse when sealing the wound during cataract surgery by Daniel H. Chang, MD

The comprehensive cataract surgeon and glaucoma by Kerry D. Solomon, MD

Zonular can complicate cataract surgery Zonular can complicate cataract surgery
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