This article is from September 2006 and may contain outdated material.
Cataract surgeons are breathing new life into the 30-year-old technique called iris suture fixation. The concept of iris suture fixation for posterior chamber intraocular lenses (PCIOLs) dates back to 1976, when Malcolm McCannel, MD, described a transcorneal, retrievable suture technique to refix, resuture or stabilize subluxated PCIOLs. Recently, however, ophthalmologists have reported taking the procedure to the next level and are using it in patients who do not already have a posterior chamber lens.
Now the technique is being used to implant PCIOLs into eyes with inadequate capsular support, as well as repair late in-the-bag lens dislocation, which threatens to become epidemic.
Samuel Masket, MD, predicts that “more and more doctors will adapt this technique,” which involves inserting a three-piece, foldable acrylic lens through a 3.5-mm incision and then securing it with a modified McCannel slipknot suture.
“There are tremendous advantages to this technique,” said Dr. Masket, clinical professor of ophthalmology at the University of California, Los Angeles, and in private practice. “The number one reason I suture to the iris is complication from original surgery, in which there was a capsule rupture, or the lens became malpositioned.”
“Each case is different from the one before,” said Dr. Masket, who recently used the technique four times in one week. Two cases were the result of complications of the original surgery, one was from pseudoexfoliation, and in the last, he removed an anterior chamber lens because of chronic pain and inflammation and replaced it with a PCIOL sutured to the iris.
“If there’s tremendous weakness of the zonules, this technique is ideal,” said Walter J. Stark, MD, professor of ophthalmology and director of cataract and cornea services at Wilmer Eye Institute. It’s ideal, he explained, because the manner in which the IOL is fixated prevents later subluxation or dislocation. While compromised capsular support is rare, Dr. Stark, estimates that 20 percent of his patients are predisposed to weak zonules due to pseudoexfoliation or some other factor, like traumatic cataract.
Perhaps 10 percent of the patients in a more typical practice might present with weakened zonules, though Garry P. Condon, MD, said the number varies by locale due to demographic factors. Greeks and Scandinavians, for example, have a high incidence of pseudoexfoliation.
Fixing dislocation. Iris suture fixation is also useful for treating the increasing number of cases of late in-the-bag IOL dislocation, a complication that appears to be related to the advent of continuous curvilinear capsulorhexis.1 “Rather than taking the [dislocated] lenses out and using big incisions, iris fixation can be used in many of those cases as well,” said Dr. Condon, associate professor of ophthalmology at Drexel University, Philadelphia, clinical assistant professor of ophthalmology, University of Pittsburgh, and in private practice.
Dr. Condon first sutured a lens to the iris in a patient with bad glaucoma related to a symptomatically intolerable anterior chamber IOL implant. He removed the ACIOL and performed a trabeculectomy. The surgery controlled the pressure, but with no lens in his eye, the patient had blurred vision and a limited visual field. “He wanted something done,” Dr. Condon said. A contact lens wasn’t tolerated, and suturing a lens to the sclera would violate the conjunctiva. Dr. Condon’s dilemma: How to treat the aphakia without disturbing a functioning filtering bleb?
That’s when he hit on the idea of using a three-piece, foldable acrylic posterior chamber lens. In this approach, Dr. Condon unfolds the lens so that the optic is captured by the pupil, while the haptics extend outward behind the iris. The temporary optic capture stabilizes the lens while he places modified McCannel sutures (using the Siepser sliding knot) in the peripheral iris to fixate the haptics. Then he prolapses the optic back through the pupil.
Lasso That Lens
Both Drs. Condon and Stark provided detailed descriptions of iris suture fixation using an AcrySof lens, a 3.5-mm incision, and 10-0 polypropylene, with modifications to McCannel’s suture idea.2, 3 They each pass a suture through clear cornea and the iris, under the peripheral aspect of the haptic, then out through the iris and clear cornea.
Dr. Stark then creates a paracentesis over the haptic, and pulls two ends of the suture through this site. The other haptic is secured in a similar manner. The sutures are loosely tied with a single throw and are not locked. Then the optic is placed posteriorly to the iris, the iris is manipulated to produce a round pupil and the sutures are securely tied.
In contrast, Dr. Condon prefers the security provided by a modified Siepser sliding knot.4 “I strongly advocate the use of some form of a Siepser sliding knot for haptic fixation because the risk of haptic slippage is otherwise very real,” he said.
Dr. Stark recommends using a lens that is 0.5 D less in power than indicated for a posterior chamber IOL. This compensates for the positioning of the lens, which is more anteriorly placed than if it were in the capsular bag, he said.
Dr. Condon, on the other hand, recommends using the standard in-the-bag IOL power calculation because of the resulting relative posterior optic position with his technique.
Iris Fixation: Both Sides Now
- 3.5-mm incision
- Doesn’t disturb the conjunctiva (important for eyes with glaucoma)
- Safe in eyes with preexisting superior blebs
- No loss of chamber depth
- Minimal induced astigmatism
- Reduced risk of suprachoroidal effusion
- No externalized suture, so reduced risk of endophthalmitis
- Improved suture longevity compared with scleral fixation
- Less challenging than scleral fixation
- May be used with cataract surgeries complicated by loss of capsular support
- Requires enough iris tissue to support a lens
- Suturing technique may disturb the shape of the pupil and create “ovalling.” According to Dr. Masket, “The best way to avoid that is by sewing more toward the periphery than toward the pupillary margin.”
- Potential loss of the IOL into the posterior chamber, if there is less-than-adequate pupillary capture
- Not suited for a silicone lens, which is slippery and difficult to maneuver
- Should not be attempted without practicing on animal or cadaver eyes
Learn first. Iris suture fixation isn’t technically difficult, though there is “a short, but real, learning curve,” said Dr. Masket, who advises practicing on animal or cadaver eyes.
Proponents of the technique agree that it is a promising alternative to the more technically challenging scleral fixation, which can lead to lens dislocation or late endophthalmitis. And a 3.5-mm incision has obvious advantages over the large corneal incision required for ACIOLs, which also carry the potential for corneal decompensation and chronic inflammation.
One drawback, said Dr. Masket, is the current dearth of adequate suture materials and needles. “Manufacturers are behind the curve on this, not recognizing the evolving popularity of this technique.” For intraocular maneuvers, Dr. Masket prefers a new series of microinstruments made by MST of Seattle. Aside from proper equipment, surgeons must possess a degree of comfort in working with pars plana entry to prevent the lens from falling into the posterior segment, Dr. Masket said.
Dr. Stark agrees. “It’s a complex operation that requires a clear understanding of where to put the sutures,” he said. “It also requires the ability to perform an anterior segment vitrectomy, either through the limbus or pars plana. People who deal with complicated cases should know how to do this.”
1 Gimbel, H. V. et al. J Cataract Refract Surg 2005;31:2193–2204.
2 Stutzman, R. D. and W. J. Stark. J Cataract Refract Surg 2003;29:1658–1662.
3 Condon, G. P. J Cataract Refract Surg 2003;29:1663–1667.
4 Siepser, S. B. Ann Ophthalmol 1994;26(3):71–72.
Drs. Masket and Stark report no related financial interests. Dr. Condon is on the speaker’s bureau for Alcon.