April 2010




Z syndrome still possible with newer generation Crystalens

by Michelle Dalton EyeWorld Contributing Editor 


An uncommon complication has experts trying different remedies

Note the bands of striae/fibrosis in the posterior capsule, which has led the inferior part of the optic to shift forward, while the superior part of the optic has shifted posteriorly Source: William B. Trattler, M.D.

Following YAG capsulotomy, the Z syndrome has resolved, and the IOL has returned to its normal position Source: William B. Trattler, M.D.

The patient presented post-YAG with Z syndrome; the temporal plate is buckled because of anterior insertion of the plate above the equator and fibrosis, leading to the superior part of the optic twisting forward and the inferior part pushing back; additionally, the lens is tilted on the plane and tilted on the plane of the plates Source: Steven G. Safran, M.D.

The Crystalens HD500, with the Z syndrome obvious from the angle of the slit beam Source: Steven G. Safran, M.D.

The same patient, after plate dissection, partial capsulectomy, a CTR inserted in the bag over the plates using a ‘fishtail’ technique, lens optic then pushed behind the posterior capsule and, finally, triamcinolone-assisted vitrectomy Source: Steven G. Safran, M.D.

The same patient; initial refraction after the Crystalens implantation was –0.25 –3.0 X 30 degrees; after resolving the Z syndrome, the patient’s refraction was ±0.25 and had an uncorrected vision of 20/25 +2 Source: Steven G. Safran, M.D.

Asymmetric folding at the haptic-optic junction of the Crystalens AT45 (Bausch & Lomb, Rochester, N.Y.) has been reported in the literature as a rare complication, but a complication nonetheless, and has been dubbed “Z syndrome.” In general, during Z syndrome, the capsule contracts and causes long-axis compression resulting in the asymmetric folding. More recently, however, the same syndrome had been reported in newer generations of the lens, including the HD and 5-0, although reports of the syndrome are extremely rare and can be avoided, experts say. In earlier generations of the lens, Z syndrome—so named because the shape of the distorted IOL resembles a stretched-out “z”—could require IOL removal. In some of the more severe complications, the IOL may have fixated into the capsular fornices, which would then require haptic amputation. The tilting of the optic can lead to coma aberration, increased myopia, and increased astigmatism, the literature notes.

“The vaulting can be mild or it can be Z syndrome, which can be resolved with YAG,” said William B. Trattler, M.D., director, Cornea, Center for Excellence in Eye Care, Miami. Two case reports he and others from the Boxer Wachler Vision Institute, Los Angeles, reported in the Journal of Cataract and Refractive Surgery note that this particular complication is unique to the hinged accommodating IOL and is not limited to the earlier iterations.1 Based on published and unpublished cases, the general recommendation is to perform an Nd:YAG capsulotomy, although “treatment depends on the configuration of the IOL and its relationship to the capsule,” according to the article. Others, however, say that performing Nd:YAG capsulotomy will not necessarily help correct the problem and may further complicate the issue. For instance, the lens may flatten but not revert back to its posterior vaulted position. The syndrome can occur “despite perfect placement of the IOL during surgery,” Dr. Trattler said. He also recommends determining if there is any striae in the capsule where the haptic is buckling. “It may be possible to target an area under the haptic with a YAG,” he said.

Options for repositioning

“With the Crystalens anterior vaulting, there is one variable that holds the most weight in deciding whether to YAG the capsule or surgically reposition with or without a capsular tension ring [CTR] implantation,” said Jack A. Singer, M.D., Randolph, Vt. “If there is a gap between the posterior capsule and any part of the IOL [optic and/or plate haptics], I would use the surgical option for the following reasons: The degree of capsule contraction force is not likely to be adequately neutralized by YAG capsulotomy alone, and the risk of anterior vitreous prolapse following YAG posterior capsulotomy is high due to the gap between the posterior capsule and the IOL.”

Dr. Singer also suggested that if the lens vaults back but not enough to be sufficient, implanting a second CTR “should do the trick.” Dr. Singer credits Alan Aker, M.D., Boca Raton, Fla., with the latter surgical pearl. “The decision to YAG versus perform surgery can best be answered by looking for a gap between the posterior capsule and the IOL optic/plates. If a gap is present, YAG is not likely to help and will likely lead to vitreous prolapse as well as complicate your future options,” said Steven G. Safran, M.D., Lawrenceville, N.J.

He added that a few patients referred to his practice were unsuccessfully treated with YAG “because posterior capsule fibrosis was not the direct cause of the problem. If one haptic buckles forward while the other is pushed back, doing YAG will generally not eliminate this unless the haptic buckled forward is in contact with the posterior capsule or there is phimosis or some other severe mechanical issue that can be directly addressed with the YAG,” Dr. Safran said. How the problem is treated should depend upon how it was caused and the amount of time past the original surgery, he said. “The concept that ‘YAG cures all’ is not correct for all patients and will lead to quite a few patients who still have a Z and are status post-capsulotomy, which is a very difficult problem to fix,” he said.

Cases where a YAG was unable to correct Z syndrome often have one plate asymmetrically inserted above or below the equator and an “impinging capsule leading to an acute angle between the plate and the optic, thus the Z,” Dr. Safran said. Still, others believe the syndrome can be resolved by performing a simple YAG. “I have helped with four syndrome cases since the AT50 SE was launched,” Dr. Trattler said. “In all of the cases, there was a Z configuration—with one part of the optic pushed back against the posterior capsule while the other part of the optic was vaulting forward. All of the cases responded to YAG capsulotomy.”

Even in cases with suspect endothelium, “I still believe that a YAG laser is the safer treatment,” Dr. Trattler added. Using a CTR in these types of cases could prove more challenging than helpful, he said. The bottom line for patients, Dr. Safran said, is that “the quality of vision with a Z is not good because of distortion of the optic, and even if a vitrectomy is required, the vision will be much better than if you still have a warped/twisted optic.”

Pearls to avoid Z syndrome

Dr. Safran believes Z syndrome is most common when there is a large rhexis in a small eye. He has further delineated Z syndrome from “Tiddleywink syndrome”—where one side of the optic is covered 1 mm-2 mm by anterior capsule “but on the other side the anterior and posterior capsule fuse well beyond the optic edge—say 1-2 mm—and you can get a tilt of the optic that can be significant.”

If an Nd:YAG does not resolve the issue, rotation of the IOL into the anterior chamber and re-inserting haptics 90 degrees away from the original orientation has been successful as well, according to some. “The problem with studying these cases is that they are not common, the eyes are all different, and the Z syndromes themselves are not uniform. YAG techniques vary as do surgical techniques. I think we are just beginning to understand this phenomenon better,” Dr. Safran said.

Some pearls that can help avoid Z syndrome in the first place, Dr. Safran said, are to make a slightly smaller rhexis (5 mm-6 mm at most), ensure the surgeon removes all the cortex and lens epithelial cells possible, and ensure the IOL rotates freely and that both haptics are in the equator of the bag.

“This is a sign that it is in the fornix/equator of the bag. Rock it back and forth and then rotate after removing viscoelastic,” he said. Additionally, as Z syndromes are “caused by asymmetric forces causing an asymmetric position, it is important to avoid these forces in the first place,” Dr. Safran said. “These can be transient forces [trauma or chamber shallowing] that are strong enough to buckle the lens into a position where it remains, or progressive sustained forces due to capsule contraction with asymmetric influence on the lens due to an asymmetric relationship to the lens anatomically.”

Another pearl, Dr. Trattler said, is “to triple check that both haptics are in the bag. Otherwise, you’ll get a condition that looks like a Z syndrome but is really ‘in and out syndrome’ where you will have to go back to surgery and reposition the lens, as a YAG will not work.”

Patients with weak zonules should not be considered for implantation with the Crystalens, and if zonules are suspect, proceeding with the use of a CTR is highly recommended, Dr. Safran said. Finally, if a surgeon opts to use a Crystalens in a tiny eye with a narrow angle, “consider using the AT over the HD as the warping caused by capsule contraction affects the quality of vision more with the HD than the AT,” Dr. Safran said. “A mini Z syndrome [or full-fledged Z] will have much more degradation of vision [induced astigmatism, myopia, and higher order aberrations] with the HD than an AT.”

Editors’ note: Dr. Trattler has financial interests with Bausch & Lomb (Rochester, N.Y.). Dr. Safran is working with Bausch & Lomb to create an instrument to help aid the surgical correction of Z syndrome. Dr. Singer has no financial interests related to his comments.

Contact information

Safran: 609-896-3931, safran12@comcast.net
Singer: 802-728-9993, jack@singereye.com
Trattler: 305-598-2020, wtrattler@gmail.com


1 Yuen L, Trattler W, Boxer Wachler BS. Two cases of Z syndrome with the Crystalens after uneventful cataract surgery. J Cataract Refract Surg. 2008;34:1986-1989.

Z syndrome still possible with newer generation Crystalens Z syndrome still possible with newer generation Crystalens
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