May 2009

 

CATARACT/ IOL

 

Simpler lens fixation option offered


By Rich Daly EyeWorld Contributing Editor

   

Smaller incisions and less manipulation in an iris fixation approach can help lower the incidence of complications when compared to other approaches for addressing loss of capsular support

A Barraquer sweep is passed through the paracentesis and placed beneath the optic as the lens is unfolded. Additional viscoelastic material is injected into the AC, pushing the iris posteriorly against the haptics. The Barraquer sweep is used to elevate the optic

A 10-0 polypropylene suture is passed on a long needle through clear cornea and the iris, under the peripheral aspect of the inferior haptic, then out through the iris and clear cornea

A paracentesis is created over the inferior haptic, and two ends of the suture are pulled through

The sutures are loosely tied with a single throw and not locked

The optic is placed posterior to the iris. A Sinskey hook is used to manipulate the iris to produce a round pupil

Miochol is injected again to ensure a round miotic pupil.

The sutures are securely tied

Source for all: Walter J. Stark, M.D

Cataract surgeons confronted with somewhat rare cases of inadequate capsular support may be tempted to send such patients to a surgical specialist. But a newer approach offers a simple alternative approach any surgeon can use to address intra ocular lens (IOL) fixation problems themselves.

Walter J. Stark, M.D., Boone Pickens Professor of Ophthalmology, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, developed a modified McCannel technique for the iris fixation of IOL in rare but potentially complicated cases of inadequate capsular support. Dr. Stark discussed the fixation technique during the 2009 ASCRS Winter Update in Cancun. The approach, which Dr. Stark has used for about seven years, allows surgeons to insert and suture-fixate an IOL through a 3.5 mm incision. The result is greater flexibility in treating patients with no capsule support. The technique compares well with scleral fixation approaches, he said, because those approaches require larger incisions and more manipulation to attach intraocular lenses to the sclera. “So this [technique] is much easier on the doctor and the patient,” Dr. Stark said.

Other advantages of the approach include the flexibility to allow secondary IOL insertion in aphakic patients who are contact lens intolerant. The technique also promises simplified management of post-op lens problems that require IOL exchange. Surgeons may also address the loss of capsule support themselves at the time of cataract surgery instead of sending patients to another surgeon experienced in addressing such IOL fixation problems.

Surgeons confronted with patients who lack adequate capsular support have long had to choose between leaving the patient aphakic, placing an anterior chamber IOL, or suture-fixating a 3-piece foldable acrylic IOL in the ciliary sulcus or the peripheral iris.

Dr. Stark moved to the modified McCannel technique in such patients when its various surgical advantages became clear.“If you understand this technique and have the necessary suture available then you can get a good result in most cases where there is a weakness of the supporting structure,” he said.

Dr. Stark’s approach in this technique begins with a 3.5 mm central incision, as well as pupil constriction with acetylcholine to facilitate papillary capture of the IOL optic. He uses a so-called moustache fold of the IOL to insert it so that the haptics are placed within the sulcus and the optic are above the plane of the iris. As the lens is unfolded, a Barraquer sweep is passed through the paracentesis and placed beneath the optic.

The technique includes the injection of additional viscoelastic into the anterior chamber to push the iris posteriorly against the haptics. The Barraquer sweep then elevates the optic. Both maneuvers aim to improve visualization of the haptics and simplify passage of the sutures.

The modified McCannel-type iris-fixation technique uses a 10-0 polypropylene (Prolene) suture on a long needle (CTC-6, Ethicon Inc., Somerville, N.J) through clear cornea and the iris, under the peripheral aspect of the inferior haptic, then out through the iris and clear cornea. Such a long needle is the only specialized equipment Dr. Stark urges for this technique because the approach may not be possible with shorter needles. After a paracentesis is created over the inferior haptic the two ends of the suture are pulled through this site. Once the superior haptic is similarly secured, the sutures are loosely tied with a single throw and not locked. The surgeon then should ensure the optic is placed posterior to the iris.

A Sinskey hook is used to manipulate the iris until a round pupil is produced. This effect is reinforced by the injection of Miochol (acetylcholine chloride intraocular solution, Novartis, Basel, Switzerland), which stimulates a round miotic pupil.

Among the final steps of the technique is securely tying the sutures, however, if the patient has a complete lack of capsular support then the sutures should be tied tight before the optic is placed in the posterior chamber. Some cases may require a vitrectomy through a pars plana incision or an anterior vitrectomy through the corneal wound. As with any such surgery, all retained viscoelastic material must be removed from the anterior chamber. Dr. Stark also injects air into the anterior chamber and checks for unidentified strands of vitreous. In cases where vitreous is detected, he uses a Barraquer sweep to break the strands or performs a more extensive vitrectomy. A second air injection into the anterior chamber and inspection for vitreous adds another safeguard. He finishes such procedures with an injection of a balanced salt solution into the anterior chamber to bring the eye to a more normal physiologic pressure. Lastly, he tests the wound for leaks.

The technique’s only complication that surgeons should watch for is the potential for ovaling of the pupil. The probability of this complication is minimized, Dr. Stark said, through the careful placement of the sutures. Surgeons should use a small amount of iris and locate the sutures near the periphery to minimize the chance for ovaling.

Editors’ note: Dr. Stark has no financial relationships related to the subject of this article.

Contact information

Stark: 410-955-5490, wstark@jhmi.edu

Simpler lens fixation option offered Simpler lens fixation option offered
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