This article is from January 2009 and may contain outdated material.
Over the years, one of the challenges facing cataract surgeons has involved implantation of a primary or secondary intraocular lens in the absence of capsular support. In an effort to find a safer, more stable, more easily performed and monitored method, Kenneth J. Rosenthal, MD, has developed a new technique that he said gives surgeons a viable option for patients with inadequate capsular support.
Dr. Rosenthal, an associate professor of ophthalmology at the University of Utah in Salt Lake City, proposes using an IOL designed and approved for use in the posterior chamber as a sutured anterior IOL, which, he said, represents a simpler alternative to traditional posterior chamber IOL suturing or anterior chamber IOL insertion.
Historical Methods of Fixation
“Early IOLs were primarily placed in the anterior chamber,” Dr. Rosenthal noted. “The next generation involved angle-fixated anterior chamber IOLs, iris-fixated anterior chamber IOLs, sclera-sutured posterior chamber IOLs and iris-fixated posterior chamber IOLs. These techniques are technically demanding, time-consuming and fraught with imperfections.”
Angle fixation. While the anterior chamber IOL implantation is generally successful, the angle-fixated technique carries with it some risks includ ing corneal decompensation, ovalization of pupils and glaucoma. “There is also chronic pain associated with angle-fixated anterior chamber IOL implantation in a subset of patients who receive this lens,” Dr. Rosenthal said. “This may be due to pressure from the haptics or from inflammation in the anterior chamber angle.”
Scleral sutures. The sclera-sutured PCIOL, which is useful in some instances, also has its problems. First, Dr. Rosenthal noted, the surgery tends to be demanding and time-consuming because of the need to make scleral flaps to bury the fixation sutures. There also is the potential for dislocation, torque or decentration. Endophthalmitis from erosion or bacterial ingress around the suture is another concern.
“I have largely abandoned this procedure except in cases of partial or total aniridia, such as in suturing iris prosthetic implants as part of a clinical trial in which I am an investigator, where there is no choice of technique,” he said.
Fixing PCIOLs to the iris. Iris-fixated PCIOLs are “usually very satisfactory, especially when repositioning subluxated IOLs,” Dr. Rosenthal noted. However, the technique is surgically demanding, with a risk of ovalization of the pupil and decentration and/or torque, he said.
Anterior implantation, but without sutures. In the past, PCIOL implantation in the anterior chamber was attempted without fixation but with poor results, Dr. Rosenthal said.1
He pointed to associated problems such as bullous keratopathy, shifting visual acuity due to decentration and anteroposterior shifting of the optic, and the possibility of glaucoma perhaps related to fibrotic encapsulization of the haptics in the angle. A related technique is described in the Canadian Journal of Ophthalmology,2 said Dr. Rosenthal. “Posterior chamber IOLs are implanted in the anterior chamber with fixation achieved by threading the haptics through iridotomies.” Dr. Rosenthal is concerned, however, that trauma could easily cause dislodgment of such an implant.
A New Approach
When Dr. Rosenthal was developing his approach, he realized that one of the major problems with the implantation of PCIOLs in the anterior chamber was the mechanical rubbing of the lens on the surface of the iris. “These IOLs are highly mobile, and it is easy for the lens to get in trouble,” he said. “So I thought of implanting the posterior chamber lens in the anterior chamber with a suture to stabilize the lens.”
The benefits. The advantages are many, Dr. Rosenthal said. “First, my goal was to ease the technical challenges of suturing posterior chamber IOLs,” he said.
He also sought to improve the observability of the IOL, as well as make it easier to exchange the lens, if necessary. In addition, the approach removed the mechanical problems associated in the past with anterior chamber placement. From an optical standpoint, except for a recalculation of the correct IOL power, there should be little or no difference between the anterior chamber and posterior chamber placement for the patient, Dr. Rosenthal said. “In essence, it is easier to center, easier to suture and easier to maintain.”
The nuts and bolts (and haptics). It is important to first evaluate the anterior chamber depth to ensure there is adequate space for the proposed placement of the IOL. The surgeon next places an acrylic three-piece posterior chamber IOL—which can be either monofocal or multifocal—and sutures it to the anterior surface of the iris. Dr. Rosenthal uses 10-0 polyester sutures (Moria) and avoids contact between the haptics and the anterior chamber angle by crimping the distal half of the haptics so that they bend toward the optic. “I assure centration of the IOL by marking the geometric center of the cornea and aligning it with the center of the IOL at the time of placement,” he explained.
Initial Cases
In the original series using this technique, Dr. Rosenthal followed eight eyes in seven patients for up to two-and-ahalf years. Patients experienced a rapid visual recovery with minimal postoperative inflammation. “Centration and stability proved better than with comparable techniques in suturing the posterior chamber IOL to the posterior iris,” Dr. Rosenthal said. “In addition, the technique was more easily performed compared with posterior chamber sutured IOL techniques. We also found that after the surgery, the position and stability of the IOL were easily ascertained.”
In terms of complications, one eye developed pupillary block glaucoma, which was treated with YAG iridotomy. Dr. Rosenthal now performs iridotomies on all patients at the time of IOL implantation. Another eye experienced vitreous haze, and the patient, who was 89, elected not to undergo a vitrectomy. Finally, one eye had transient vitreous hemorrhage that cleared to a visual acuity of 20/20 after a two-week period.
Who’s OK for this? Dr. Rosenthal noted that candidates for this procedure include patients with inadequate capsular support for a variety of reasons. He described one patient who, at age 49, had undergone bilateral intracapsular cataract extraction. As time passed, she could no longer tolerate wearing contact lenses. Dr. Rosenthal used his technique to implant bilateral ReZoom multifocal lenses. “This patient did very well with final visual acuity of 20/20 OD and 20/25 OS without correction and J1 at near,” Dr. Rosenthal said. “She is completely spectacle independent. What is remarkable is that her eyes are now as quiet as those we have seen with posterior sutured IOLs. There is no uveitis and no glaucoma. And the IOLs are perfectly centered.”
Another patient had a dislocated, subluxated lens that was too loose to salvage. Dr. Rosenthal explanted this lens and sutured a ReZoom multifocal IOL into the anterior chamber. “With this technique, rather than simply resuturing and repositioning the older lens, we can actually update the technology in the patient’s eyes. And this technique allows us to observe the centration and perfect it, which is especially important for multizonal, multifocal IOLs. We have seen decentered IOLs cause an undesired refractive error. The centration issue is also crucial with prolate optic IOLs such as the AMO Tecnis, since the amount of prolate correction decreases with decentration. If the IOL will end up centered in a predictable fashion, it is possible to make the most of the optical advantages of prolate optic lenses using this technique rather than having to settle for traditional nonprolate IOLs."
The Need for More Data
Samuel Masket, MD, clinical professor of ophthalmology at the University of California, Los Angeles, said Dr. Rosenthal’s new technique represents “a novel idea that is technically easier than some of the other suturing techniques.” Dr. Masket’s preference, in the absence of capsular support, is to sew a posterior chamber lens onto the back of the iris. “Dr. Rosenthal’s technique, because the posterior chamber IOL is sutured to the anterior iris surface, has the potential to avoid problems such as iris chafing and uveitis-glaucoma-hyphema [UGH] syndrome,” he said.
Good idea even better with data. Dr. Masket added the technique is a “clever idea” that could address the challenges of a patient who has a malpositioned posterior lens without adequate capsular support. “This concept is analogous to the Artisan lens, which clips onto the anterior surface and has merit,” he said. “However, we need long-term data to indicate the safety of the procedure.” Dr. Rosenthal noted that his series has several patients with follow-up of greater than two years, and he has not seen changes in endothelial cell population as measured by confocal microscopy in any patient.
William B. Trattler, MD, in private practice in Miami, agreed with Dr. Masket that more long-term data are necessary to determine the safety and effectiveness of this procedure. “We need a significant number of cases and good follow-up,” he noted. “We need to be sure that this technique does not result in significant iris chafing, for example, which could lead to elevation in eye pressure over time.”
Dr. Trattler added that since the lens is being sutured to the iris and there is no involvement of the angle, there is potentially less risk of developing glaucoma in the future than there is with an anterior chamber IOL. Also, since the lens is placed in the anterior chamber, if one of the sutures degrades over time, it will not drop back into the vitreous cavity as would a sutured posterior chamber IOL.
“The true test would be to determine the effectiveness of Dr. Rosenthal’s technique with presbyopic lenses, which can be challenging to perfectly center when suturing into place in the posterior chamber,” said Dr. Trattler.
In his practice, when treating patients with inadequate capsular support, Dr. Trattler currently favors implanting an anterior chamber lens because it is a very easy and safe procedure. However, elevation of eye pressure is a long-term concern. “I tend to stay away from PCIOLs sutured into the posterior chamber,” he explained. “It is time-consuming and challenging, and the sutures can erode over the course of decades.” As well, a long-term retrospective study conducted by Kendall Donaldson, MD, found that the visual results and risk of complications were similar between anterior chamber and sutured posterior chamber intraocular lenses.3 Dr. Rosenthal’s technique “has potential, but longterm data would be useful for clinicians considering this new procedure,” said Dr. Trattler.
Dr. Rosenthal, however, disagreed with the conclusions of Dr. Donaldson’s study. In that retrospective study, he said, patients overall had similar outcomes but many of the patients who had successfully sutured PCIOLs had had previously failed ACIOLs in the fellow eye, suggesting that in patient fellow eye controls, the PCIOL did better.
Furthermore, the study evaluated patients with sclera-sutured PCIOLs rather than IOLs fixated with a simpler iris fixation approach.
No UGH, Easy Explantation
Dr. Rosenthal reiterated Dr. Masket’s comment that the technique can help avoid UGH syndrome, often seen in earlier anterior chamber IOLs. “And if there is a need to explant this lens,” he said, “it would be an easier procedure.” He cited the example of a pediatric patient who would need explantation due to a power change as he or she grew older.
“The potential for this technique is substantial. It allows the surgeon to use any kind of IOL that exists today. We can then customize the choice of lens to the optical needs of the patient. Inadequate capsular support will not be a problem,” said Dr. Rosenthal, adding that he is continuing to collect data and expects to begin an expanded clinical trial soon.
___________________________
1 Hara, T. and T. Hara. Arch Ophthalmol 2004;122:1112–1116.
2 Oksuz, H. et al. Can J Ophthalmol 2007;42:337–338.
3 Donaldson, K. E. et al. J Cataract Refract Surg 2005;31(5):903–909.
___________________________
Dr. Masket receives grants and research support from Alcon, consults for Alcon, Othera, PowerVision and Visiogen and serves on the speaker’s bureau for Alcon, Allergan and Bausch & Lomb. Dr. Trattler reports research and travel support from AMO and research support from Bausch & Lomb and Lenstec. Dr. Rosenthal reports receiving travel, grant and research support from AMO and travel support from Bausch & Lomb and Ophtec.