Without a doubt, refractive surgery has revolutionized vision correction. Yet one aspect has continued to frustrate James J. Salz, MD, over the years: High myopes, the “people who need LASIK the most,” are at highest risk for problems with this surgery.
“These are the individuals who are worried about being caught in a fire during the night without their contacts or glasses, unable to see their way out of the house,” noted Dr. Salz, who is with Laser Eye Associates in Los Angeles and a clinical professor of ophthalmology at the University of Southern California. “This is why the recent [Sept. 10, 2004] approval of the Verisyse IOL is so exciting. This lens is addressing their needs.”
The Verisyse IOL (distributed by Advanced Medical Optics) has been used in Europe for almost two decades. It features an iris fixation method that enables the lens to attach to the periphery of the iris in a way that does not inhibit the iris’ function. Once anchored, the lens vaults forward, occupying the space between the crystalline lens and the corneal endothelium. This design provides for the free flow of aqueous from the posterior to the anterior chamber, thus minimizing the potential for pupillary block glaucoma.
Preferred patients. Vance Michael Thompson, MD, assistant professor of ophthalmology at the University of South Dakota in Sioux Falls, recently completed his 200th Verisyse IOL implant. “I use them mainly for patients who are not candidates for LASIK, including those with thin corneas [under 500 micrometers] who are –5 D or more,” Dr. Thompson explained. “And when we get above 7 D of correction, I lean toward the implant regardless of corneal thickness.
“In fact, one of the things I like about the implant is that we can correct vision without removing so much corneal tissue,” he added. “Another benefit is that, if we need to fine-tune the correction, we can do a laser enhancement six months later. In my practice, we have found that about 10 percent of patients needed this enhancement.”
Problem patients. Patients who are not candidates for the Verisyse lens include those with any conditions that may lead to intraocular inflammation (such as uveitis or diabetes), the presence of cataract and an anterior chamber depth less than 3.2 millimeters.
Age may also be a factor, according to George O. Waring III, MD, founding surgeon of the InView Refractive Center in Atlanta. For patients under age 55, the Verisyse lens may prove an excellent option. “However, the Verisyse lens is not accommodative, nor is it multifocal,” Dr. Waring pointed out. "Consequently, patients over age 55 with serious presbyopia may want to consider refractive lens exchange” instead.
What about retinal detachment? This brings up another factor when considering implants: the risk of retinal detachment. Interestingly, while refractive lens exchange does raise the risk of retinal detachment, it appears that the Verisyse IOL does not increase this risk. Dr. Thompson explained that the risk is higher in refractive lens exchange because after the crystalline lens is removed, the posterior capsule, which is attached to the vitreous, moves forward—creating tension that can lead to retinal tears, holes or retinal detachments. Since the Verisyse lens is implanted without removing the crystalline lens, retinal detachment is less of a concern.
Dr. Waring implanted his first Verisyse lens in 1993, working with inventor Jan Worst, MD, of Groningen, the Netherlands, in both Europe and Saudi Arabia. Dr. Waring served as one of the investigators in the U.S. clinical trials, and performed approximately 150 cases in the United States. He noted the technique requires that surgeons learn the technique of “enclavation,” which is used to fixate the lens to the anterior iris surface. Specifically, the lens has two pincerlike haptics through which a small knuckle of iris is drawn during implantation by enclavation.
The technique begins with a 6.5-mm incision in the limbus. “The next step is to fill the eye with viscoelastic and then slide the IOL in through the limbal incision,” Dr. Waring said. The lens must be centered over the pupil, and care must be taken to avoid contact with the natural lens and the corneal endothelium.
Next comes the enclavation step. Paracenteses are used for the introduction of enclavation needles and enclavation forceps. An enclavation needle is inserted through one paracentesis to fixate the lens to the iris. While securely holding the lens body with the implantation forceps, the surgeon uses the enclavation needle to create a small “knuckle” of iris tissue. A “snow-plowing” movement is then made at the desired fixation site.
A significant fold of iris tissue must be delivered through the haptic slot to ensure adequate lens stability. If the fold of the iris is too small, the IOL can luxate forward and cause damage to the endothelium. The enclavation needle is then retracted and transferred to the opposite hand, where the technique is repeated. Finally, the viscoelastic is removed and the incision closed.
Dr. Waring noted that an adequate amount of iris must be used to attach the lens or the lens may come loose. If the lens does come loose, the patient is then returned to the OR where the lens is reattached.
Added Dr. Thompson, “Enclavation and centration over the pupil are the two challenging aspects of the surgery. With enclavation, you don’t want to grab too much or too little iris with the claws. You are aiming for approximately 1 mm of tissue.”
The Verisyse lens is implanted one eye at a time, with at least a two-week wait between eyes.
For Dr. Waring’s patients, the results are “nothing short of phenomenal. High myopes who can’t get across the room wake up the next afternoon and realize that they can see everything. This realization causes them to break down in tears—grown men included.”
Dr. Thompson also reports high patient satisfaction, with only one patient out of 200 not achieving success with the lens. With this patient, Dr. Thompson ultimately discovered that while the implant was the perfect power, the woman’s crystalline lens would not relax. “To rectify the problem, we simply removed the implant and she returned to her contacts,” he said, adding that “this illustrates the true benefit of the Verisyse technology. You have the option to remove it and the patient can return to contacts or glasses.”
Dr. Thompson added that the Verisyse lens has a good safety profile, “and most problems can be avoided by adequate training in surgical technique.” Said Dr. Waring, “The iris claw lens technology has been used for 25 years throughout Europe and Latin America. Approximately 400,000 lenses so far have been implanted.”
Not So Fast: Wishing on a Staar
For Dr. Salz, the fact that implantable IOLs are now a reality for high myopes is reason enough for excitement. He worries that sometimes surgeons are pushing the limits of LASIK in order to accommodate high myopes, which may in turn lead to malpractice cases. “The implantable IOLS are a better way to fix abnormal corneas.”
However, Dr. Salz has not yet implanted one Verisyse lens. Instead, he is waiting for FDA approval of the Visian lens (Staar) for his highly myopic patients because “it is a better lens.”
Dr. Salz said, “A significant disadvantage of the Verisyse lens is that it requires a 6.5-mm incision, and you have to suture that incision. No surgeon likes to suture incisions, and we haven’t had to do so in the last five or 10 years. In contrast, the Staar lens is soft and made out of collagen, so it can be placed into a smaller 3-mm incision.
“Second, [the Verisyse IOL] is a more complex lens to implant. You have to clip the lens to the iris to fixate it through enclavation, which is a little tricky.”
Finally, Dr. Salz is concerned about the “sparkly effect” that is caused by the lens, which causes the lens to twinkle in the eye. “While this is not a huge issue when faced with high myopia, I still consider it a disadvantage and will wait for approval of the Visian lens.”
Are They Mainstream Yet?
Dr. Waring predicted that while the Verisyse IOL will become increasingly popular, the rate of acceptance will be slow, for the following reasons:
Small patient group. The number of high myopes is fairly small, with fewer than 5 percent of patients falling into the high myopic range.
Surgical challenges. The technique demands new surgical skills, requiring surgeons to take the time to attend a course.
“Cataract surgeons will adopt the technology first—they can do cataracts in the morning and then implant four or five of these lenses in the afternoon,” Dr. Waring said. This is in contrast to many refractive surgeons, “who are already wedded to the laser. Some have lost their intraocular surgery skills.”
Dr. Waring is a consultant for AMO. Drs. Salz and Thompson have no related financial interests.