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Clinical Update: Anterior Segment
Iris Prostheses: Repairing the Windows of the Soul
By Marianne Doran, Contributing Writer
 
 

Only a handful of people receive them each year, but for those who do, artificial iris implants mean the difference between functioning normally and being visually and socially handicapped. In the United States, the first prosthetic irides were implanted about 10 years ago. Essentially orphan devices and available only under a compassionate-use exemption from the Food and Drug Administration, the prostheses have had a good track record. But the red tape involved in obtaining FDA approval to implant a device has limited their use.

“The need is out there, the devices are out there. It’s just that the process is so onerous,” said Samuel Masket, MD, clinical professor of ophthalmology at the University of California, Los Angeles. “If we had a way to streamline the process, far more patients could benefit from the technology.”


A New Iris on the Horizon

If all goes well, surgeons may soon have easier access to the Ophtec model 311 iris reconstruction lens. The model 311 is a single-piece, PMMA-based lens-and-iris diaphragm combination and is the first artificial iris to be tested in a U.S. clinical trial. Primary indications are traumatic or congenital aniridia and iris coloboma.

The model 311 is implanted into an aphakic or pseudophakic eye, typically through a 10-mm incision. It is placed in the capsular bag or placed or sutured into the sclera or ciliary sulcus. The opaque, colored portion of the device is 9 mm in diameter and is available in brown, blue and green. The clear lens provides a fixed pupil size of 4 mm, small enough to limit excessive light and to reduce glare and photophobia. The device is custom-made for each patient.

Ninety-two patients have received the Ophtec implant as part of the core study. However, the FDA has allowed another 97 people to have the surgery as part of sub-studies within the trial, and an additional 81 patients now have the device through a compassionate-use exemption.

The German company Morcher makes a comparable device in its 67 series, but the devices are available only in black. The Ophtec color selection, although limited, offers a significant cosmetic advantage.

“The Ophtec trial is nearing the end, and we’ve had spectacular results with the model 311 almost universally,” said Kenneth J. Rosenthal, MD, who is one of the study investigators. “We’re hoping that the FDA will review the data very soon and make the device available to the public. Until these devices are available to the ophthalmologist at large, there’s always going to be some hardship involved in obtaining them.”

Challenging circumstances. Francis W. Price Jr., MD, medical monitor in the Ophtec trial, noted that the trial posed some unique issues with approval, especially in terms of the study participants. Instead of the well-matched, otherwise healthy patients selected for a typical intraocular lens trial, patients in the Ophtec trial represent a compendium of ocular problems. “Two-thirds of the people are having the surgery because of injury, and the other third because of congenital aniridia,” said Dr. Price. “Both groups have a significant incidence of everything. Those with congenital aniridia have glaucoma, corneal problems and retinal problems. Many of the traumatic injury patients have already had retinal detachments, some have had corneal transplants or are going to need them, and they’ve had glaucoma filters and drops.”

Changed lives. These coexisting conditions make evaluating patient outcomes more difficult. But the indisputable fact, according to Dr. Price, is that the implant dramatically improves light sensitivity and symptoms of glare. He credits both the company and the FDA for undertaking a trial they didn’t have to pursue but did anyway because they knew the need was so great. “There aren’t many people who need this, but the people who do, need it very badly,” Dr. Price said. “For some of the congenital aniridic patients, this is the first time they’ve been able to hold their head up when they’re in any kind of light, even normal lighting inside a house. They can have normal posture, open their eyes and look normal. It is truly life-changing.”


More Innovations Under Way

Building on this success are several other approaches:

Modular system. Ophtec plans to conduct another clinical trial, Dr. Rosenthal said, this time with its Iris Prosthetic System (IPS). The IPS is a modular system of combinable elements designed for in-the-bag fixation and insertion through a small incision (about 3.5 mm).

Ring-and-fin diaphragm. Similar to the IPS are two other Morcher devices: the 50C, or Rasch-Rosenthal device, developed by Dr. Rosenthal and a colleague, Volker Rasch, MD, and the 50E, or Masket-Rosenthal device, designed by Drs. Rosenthal and Masket. These devices rely on an intraocular lens and two multi-fin endocapsular rings that are sequentially inserted into the capsular bag. The rings are aligned and rotated so that the fins interlock, creating a full iris diaphragm. The 50E implant creates a 3.5-mm pupil compared with a 6-mm pupil with the 50C.

Color options. Robert H. Osher, MD, professor of ophthalmology at the University of Cincinnati, said that Russian ophthalmologists are working on several innovations in iris implants. “In Russia, there are now 12 color options, and the surgeon is able to pick and choose. We’re now at a point where it is possible to achieve a great functional result as well as a great cosmetic result.”

Foldable lenses. Russian researchers have also developed novel materials to make lenses that are foldable. “You can insert a full-size lens, and it’s no longer a brittle device,” Dr. Osher noted. “You can fold it, which reduces the incision size by approximately half. It’s a major advance.” Dr. Rosenthal noted that Morcher and Ophtec are both working to develop foldable devices.

Modified knot. In an attempt to obtain the best cosmetic result possible, Dr. Osher has modified the Siepser slip-knot technique, which allows cosmetic reconstruction of the patient’s partially missing iris.1 “If the patient has some residual iris left, the technique allows us to suture the pillars of remaining iris around the defect. I can use this suture technique to close the defect if it’s small or, for a larger defect, implant a prosthetic iris device but still suspend or suture the patient’s own iris tissue to provide as much normal color as possible.”


Skill and Training Required

As artificial iris devices become more accessible, more physicians may want to include prosthetic iris implantation in their practices. But there is a learning process. Dr. Rosenthal contends that most surgeons are trained well enough that with proper instruction they can master the necessary techniques. “These procedures are considerably more involved, especially for the devices that have to be sutured into the eye, like the Ophtec 311,” he said. “If there is no capsular bag, you have to create a suspensory system for the implant. There are concerns about lens rotation and stability and about anteroposterior placement of the lens because there are no landmarks—no iris to tell where in the anteroposterior plane to place them.”

First, practice outside the eye. Dr. Rosenthal added that the multicomponent small-incision devices, which are intended to be placed in the capsular bag, also pose challenges but are more straightforward to implant. “The pieces of these devices have to fit together precisely. Generally, I recommend that people do it on dry land a few times,” he said. “Get some trial devices and work with them the way you’d work with Tinker Toys before putting them inside the eye, where it can be a little tricky getting everything in.”

Dr. Price noted that because the single-piece Ophtec 311 requires a 10-mm incision, surgeons need to be comfortable in doing that type of incision and in putting in sutures. When there is no capsular support, the surgeon needs to know how to suture-fixate lenses to the sclera. “It’s a bit more difficult than doing a standard posterior chamber lens that you fixate to the sclera,” he said. “It’s less forgiving because you don’t have an iris to cover up if it’s displaced a little from one side to the other. You have to have precise placement of your fixation sutures. Then in a number of these cases you may have to do a vitrectomy with it. So I think it’s helpful if surgeons are adept at doing pars plana vitrectomy.”

New eyes for grateful patients. By all accounts, the extra training and effort will be richly rewarded. Dr. Price said people who receive an artificial iris are among his happiest patients. “It’s not unusual to have them come in for their one-day exam, and you can tell that their patch has been taken off and put back on. When you ask them what happened to their patch, they say a little sheepishly, ‘I just had to look.’ These devices are not something the companies or the doctors are going to get rich off of, but they allow us to really help people out—and that’s why we’re in medicine.”

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1 J Cataract Refract Surg 2005;31:1098–1100.
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Dr. Masket is a consultant for Alcon, Visiogen, PowerVision, Othera and Omeros. Drs. Osher, Price and Rosenthal report no related financial interests. Drs. Price and Rosenthal are investigators in the Ophtec study.