U.S. surgeons who use phakic intraocular lenses for a certain segment of their refractive surgery patients are usually pleased with the results they get, but are hamstrung by the lack of a toric phakic lens, and are forced to manage these patients’ astigmatism with another procedure. Here, surgeons from outside the United States and members of the industry discuss the current results of toric lenses and give an update on where the devices stand in the approval process in the United States.
Staar’s Toric Visian ICL
The Visian Lens takes a different tack than the Veriflex/Artiflex in that it’s a posterior-chamber phakic implant. Like an iris-fixated lens, a posterior-chamber IOL comes with its own set of pros and cons, but surgeons who use the toric ICL, or TICL, say they’re satisfied with their results.
“We use the toric ICL for patients with 1 D of astigmatism and up,” says Erik Mertens, MD, of Belgium’s Antwerp Eye Center. Dr. Mertens has implanted 700 toric ICLs. “Even in candidates who are eligible for LASIK, we still present them with the choice of having a toric phakic lens; it’s positioned beside LASIK, not just as an option for patients who aren’t LASIK candidates. The patients need to be between 21 and 50 years of age, have sufficient anterior chamber spacing—at least 2.8 mm from the endothelium—and can’t have any ocular pathology such as high intraocular pressure. However, someone with dry eye can still be a good candidate.” In Europe the TICL is approved for myopia from -3 to -23 D and for astigmatism ranging from 1 to 6 D.
The amount of vault with the lens is critical, since it’s near the crystalline lens. To get it right, surgeons usually take multiple measurements. “We use the white-to-white measurement from the Orbscan and also a sulcus-to-sulcus measurement with an ultrasound biomicroscopy device,” says Dr. Mertens. “If the white-to-white measurement is very close to the sulcus measurement, we use the sizing recommendation from the software provided by the manufacturer. If the sulcus measurement is smaller than the white-to-white, we downsize the ICL. If it’s much larger, we order a lens that’s longer than we would use based on the white-to-white measurement.”
Saudi Arabia’s Alaa El-Danasoury, MD, says that, even though vaulting is critical, there is a range of “safe” vaults inside the eye. “If you have a vault that’s between 300/350 µm and 900 µm, the refractive outcome will be excellent and you won’t see any complications related to the vault,” he says. “If you have too shallow or too high a vault, you might have cataracts or high IOP. But the lens can sit on the zonules, ciliary body processes or in the sulcus, so we have a range of forgiveness for vaulting.” An iridectomy is necessary for all ICL patients preop.
Kimiya Shimizu, MD, of Sagamihara, Japan, performed a prospective, one-year study of the toric ICL in 56 eyes of 32 consecutive patients.1 The patients’ preop spherical errors ranged from -4 to -17.25 D and their astigmatism ranged from -0.75 to -4 D. A year postop, the average uncorrected visual acuity was 20/16 and the average best-corrected acuity was 20/12.5. Ninety-one percent of the eyes were within 0.5 D of the targeted correction, and all were within a diopter of it. At a year, the mean cylinder was -0.41 ±0.36 D. Five (8.9 percent) of the eyes required ICL repositioning within a week after surgery due to rotation of more than 10 degrees. Anterior subcapsular cataract developed in three eyes (5.4 percent) but the patients didn’t need ICL removal because they were asymptomatic and showed no changes in best-corrected vision.
Dr. El-Danasoury says he’s had a low incidence of cataract formation postop. “I’ve had four cases of cataract in three patients after ICL implantation out of 1,000 implantations,” he says. “In these cases I took the lens out and implanted a posterior chamber IOL and the patients were very happy with the outcome. This low rate is acceptable.”
In the United States, Staar has submitted its application for approval for the toric Visian to the FDA. “We’ve responded to all questions from the FDA regarding the toric ICL submission,” says Staar CEO Barry Caldwell. “As we’ve said before, there are three things that can happen to the submission: it can be approved; it can not be approved or it can be sent to the ophthalmic advisory panel for recommendation.”
The Veriflex/Artiflex Toric
The PMMA Artisan toric lens has been approved in Europe for eight years, and now commands around 70 percent of the Artisan lens market there (vs. the spherical version), according to Rick McCarley, president and CEO of Ophtec USA. The Artiflex and Artiflex toric lenses, foldable silicone versions of the Artisan lens, were approved in Europe in 2010, and are gaining in popularity because they only require a 3.2-mm incision for implantation, compared to the Artisan’s 5- or 6-mm wound. The new lenses can correct up to 8 D of cylinder and as much as 15 D of myopia.
Jose Güell, MD, of the University of Barcelona, has implanted about 300 Artiflex toric lenses, and says working with them is very similar to working with their spherical counterparts. He will even implant them in lower levels of myopia for which many surgeons use LASIK. “It’s recommended that the minimum central anterior chamber depth be 3 mm, as measured from the endothelium,” he says. “And we wouldn’t want to implant it in any eye with anterior segment disease or unhealthy endothelium, which are general criteria for any phakic IOL implantation. What makes a good candidate is in some ways an open list depending on the surgeon. For instance, for me a normal cornea in a -6 D myope is a candidate for an Artiflex implant. For most that would be a good candidate for LASIK.”
Surgeons will have to find a way to mark the astigmatic axis that they’re comfortable with. “Some surgeons prefer to use specific instruments to do the marking in the operating room,” says Dr. Güell. “I, like some others, prefer to make orientation marks at the slit lamp preoperatively. During the surgery with this lens, once you have the reference point under the microscope you can precisely locate your astigmatic axis, implant the lens and proceed with enclavation.
“For experienced Artisan surgeons, I think using the enclavation needle is as easy with the toric lens as it is for the spherical,” Dr. Güell adds. “But for new surgeons, a new instrument Ophtec is introducing, which uses a suction tip to suck up the iris immediately beneath the claw, will be helpful.” The astigmatic axis of the lens is aligned with the axis of the claws, so once the lens is fixated, it’s also on-axis.
With some phakic lens designs, proper preop sizing is critical, but Dr. Güell says it’s not as crucial with the Artiflex. “This is one of the lens’s main advantages,” he says. “It’s 8.5 mm in length with a 6-mm optic and can be positioned over the pupil in the correct axis. You don’t need to take preop angle-to-angle or sulcus-to-sulcus measurements.”
In a European multicenter study of the Artiflex toric in which Dr. Güell participated, 125 eyes received the lens and were followed for six months. The average preop spherical equivalent refraction of the eyes was -7.58 D, which the lens reduced to -0.06 D at six months. The astigmatism was reduced from an average of 2.24 D to 0.36 D. Eighty-two percent of the eyes were within 0.5 D of the intended refraction, and 99 percent were within 1 D. In terms of acuity, the percentage of patients seeing 20/20 or better best-corrected preop was 67.5 percent, while 63.6 percent saw 20/20 or better uncorrected postop. The most common complications in the study were pigmentary deposits on the lens (15.8 percent), non-pigmentary deposits (12 percent) and glare (9.6 percent). “The deposits were clinically insignificant in more than 90 percent of the cases,” says Dr. Güell. “And most of the clinically significant cases resolved with steroid treatment.”
At this stage of the game in the United States, Ophtec’s Mr. McCarley says that AMO is currently in charge of securing approval for the spherical version of the Veriflex/Artiflex lens. “That study’s going relatively slowly,” he says. “But we’ve taken steps to increase the rate of enrollment for 2011. The plan is to follow the Veriflex/Artiflex approval immediately with a submission for approval of the toric version.”
1. Kamiya K, Shimizu K, Aizawa D, Igarashi A, Komatsu M, Nakamura A. One-year follow-up of posterior chamber toric phakic intraocular lens implantation for moderate to high myopic astigmatism. Ophthalmology 2010;117:12:2287-94.