Phakic IOLs Find a Solid Niche
But coming advances may have only modest impact
BY JERRY HELZNER, SENIOR EDITOR
Phakic IOLs have been an accepted staple of European refractive surgery for decades, but it is only within the past five years that these lenses have been approved or use within the United States. The introduction of phakic IOLs in this country had been met with some skepticism, as more than a few surgeons waited to be convinced that the lenses could provide both excellent vision and a high level of patient safety.
The reluctance by some to initially embrace phakic lenses was sparked by problems caused by previous designs that had been used in Europe. But proponents of phakic IOLs asserted that the designs approved by the FDA had shown in clinical trials that they could be implanted in appropriate patients with a high degree of confidence. Phakic advocates pointed out that these lenses can provide superior vision to a patient for many decades, have low complication rates with appropriate patient selection and monitoring, require a low level of postop care and can be explanted without much difficulty if the need arises. In addition, implanting phakic IOLs can provide a relatively easy entry into refractive surgery for cataract surgeons.
Almost all of the initial concerns about phakic lenses centered on fear of possible complications such as endothelial cell loss with an anterior chamber implantation, the potential for cataract formation with a posterior-placed lens and pupil ovalization with an angle-supported lens.
The good news is that US surgeons who have extensive experience in implanting phakic IOLs give them high marks for providing excellent quality of vision for pre-presbyopic higher myopes and moderate myopes. The large majority of these patients are not good candidates for LASIK, but some practices report that even LASIK qualifiers — such as professional photographers and race car drivers — have opted for phakic IOLs based on their individual needs for the best possible visual result.
In addition, highly positive longer-term efficacy and safety data are now available on the two currently FDA-approved phakic IOLs, largely eliminating concerns about potential complications in properly selected patients and contributing to surgeon confidence in recommending these lenses to patients.
Acceptance of these lenses has now reached the point that the 2009 “US Trends in Refrac tive Surgery” survey reports that phakic implantation is the procedure of choice for a 30-year-old −10 D myope.
The Verisyse phakic IOL attaches to the anterior iris stroma.
Tempering this enthu siasm is the fact that phakic IOLs remain a niche procedure for a limited patient population and currently account for only about 2% to 3% of all refractive surgeries performed in the United States. In addition, the lenses are not approved for hyperopes in the United States because of the relatively small spaces available in the typical hyperopic eye, though phakic IOLs are being used for hyperopia internationally.
When LASIK Isn't an Option
“My results with phakic IOLs have been excellent and the complication rate has been low,” says Elizabeth A. Davis, MD, FACS, of Minneapolis, “However, LASIK offers faster recovery and is less expensive. I will do LASIK on myopes up to −12 D if the eyes have no irregularities. The basic niche for phakic IOLs essentially comes down to myopes who are not LASIK candidates.”
Currently, US surgeons have the choice of using two FDA-approved phakic IOLs: the foldable, collamer Staar Visian ICL posterior lens or the non-foldable Verisyse from Abbott Medical Optics, which requires a larger incision and that attaches to the anterior iris stroma. The learning curve for Verisyse implantation tends to be steeper than for the Visian, but many surgeons say that, depending on the needs of the individual patient, they use both of these lenses with confidence.
The Visian ICL was approved by the FDA in 2005.
Dr. Davis says that some upcoming events could slightly increase the number of patients receiving phakic lenses.
“The Visian toric could be approved soon and that could broaden the patient base somewhat,” she notes. “And the fact that Alcon has a phakic IOL in late-stage clinical trials could also help the category. Just the presence of an Alcon in phakic IOLs could create additional awareness. There is also potential for a multifocal phakic lens. However, any bump up from new advances won't be huge, maybe up to 5% to 10% of refractive procedures.”
Robert Rivera, MD, of Barnet Dulaney Perkins in Phoenix, says his practice differs from some in that they proactively offer the Visian lens as an option to both LASIK candidates and non-candidates alike.
The Alcon AcrySof CacheT Phakic is in late-stage clinical trials.
“We are doing about 40 to 50 Visians a month, including some 3 D or 4 D myopes who choose it over LASIK,” he notes. “We served as investigators in the Visian clinical trial and have implanted the lens in approximately 1,200 patients. The level of patient satisfaction is uniformly high.”
Dr. Rivera is hoping for approval of the Visian toric in the near future, as the practice has a waiting list of about 800 patients for this lens. He can implant the already approved Visian design in patients with up to 3 D to 3.5 D of cylinder. He deals with the astigmatism by making the incision on a steep axis, performing LRIs and occasionally doing a laser touch-up.
“Those patients with greater amounts of astigmatism are on the waiting list for the toric,” Dr. Rivera says.
Safety First With Phakics
Vance Thompson, MD, of Sioux Falls, SD, has long experience implanting the Verisyse and Visian phakic lenses and is also an investigator for both the angle-supported Alcon AcrySof CacheT Phakic lens and AMO's foldable version of the Verisyse, called the Veriflex.
“Many of the misconceptions about phakic lenses are the result of inexperience,” says Dr. Thompson. “There are real risks with phakics, but I take a safety-first approach. I have specific criteria to determine who might be a good candidate and bring my patients back for annual monitoring. I also tell every patient that the time might come when I have to explant the lenses.”
Dr. Thompson requires every phakic lens candidate to have a minimum 3.2 mm anterior chamber depth and a baseline endothelial cell count of more than 2,000. He employs the Visante anterior segment OCT from Carl Zeiss Meditec to help make all of the essential preoperative measurements, including anterior chamber depth and estimated distance from implant to central endothelium (which he says should be > 2 mm) and peripheral endothelium (which should be > 1.5 mm). He uses the same instrument to obtain accurate postoperative measurements of true lens/endothelial clearances.
He will recommend explantation if annual monitoring shows anterior chamber below 3.2 mm or cell count drops at a rate that is more than the accepted age-related rate.
“Yearly, long-term follow-up is very important,” says Dr. Thompson. “I tell my phakic lens patients that if you come back in 20 years just to say ‘Hi,’ you could have a serious problem.”
Dr. Thompson favors the Verisyse in most patients because it has a long track record and doesn't come near the crystalline lens or the angle. However, he has no problem using the Visian if the patient has a thin iris or prefers a smaller incision.
The progress of Alcon CacheT phakic angle-supported lens is being watched closely by surgeons because a high incidence of complications — most notably pupil ovalization and/or glare — has caused previous angle-supported phakic IOLs to fail.
Dr. Thompson believes that Alcon appears to have overcome the problems that plagued previous angle-supported lenses.
“The Alcon phakic is a very soft lens that seems to be well tolerated,” he says. “It has the advantage of being quite easy to implant. The data we have so far from the current trial has been very good but I would like to see more longer-term data.”
Dr. Thompson says that patients with the angle-supported lens have to be monitored annually in three areas: anterior chamber depth, endothelial cell count, and to ensure that no synechia has formed at the angle. This complication could cause inflammation, higher IOP and endothelial cell loss.
Success With Phakic IOLs
Dr. Thompson says the three keys to successful outcomes with phakic IOLs are appropriate patient selection, surgical skill and the aforementioned annual monitoring.
He says most of his phakic IOL patients fall into the 30 to 45-year-old age range though he will implant the lenses in patients up to 50 years old if they have a deep anterior chamber, a flat iris and no other disqualifying issues.
“For patients under 30, I advise them to keep wearing contact lenses if they can,” he notes. “Implanting phakic IOLs is a surgical procedure, so if they can stay with contacts a few years longer, I encourage it.”
Dr. Rivera, who implants only the Visian, has used the lens with patients as young as 18 and up to age 54 in one patient with a clear, pristine lens.
He says one critical key to successful outcomes with the Visian lens is to obtain an accurate sulcus-to-sulcus measurement to determine proper sizing.
“Sizing is crucial for a good result,” he asserts. Sulcus-to–sulcus can be a difficult measurement but we have found that two ultrasonic instruments, the VuMax II (Sonomed) and the Ellex Eye Cubed, both provide great accuracy for the sulcus-to-sulcus measurement.”
Dr. Rivera also notes that his long experience as a cataract surgeon helped make him more proficient in implanting phakic IOLs. “I think that with phakic IOLs it's best if you already were a cataract surgeon,” he says. “The transition is more difficult if your experience is primarily working outside of the eye.”
Recent Positive Studies
The case for phakic IOLs continues to be buttressed by recent studies. For example, an article in the Archives of Ophthalmology reports on a Japanese study that closely followed 34 moderate-to-high myopes who received the Visian lens. After four years, the researchers found that 93% of the eyes were within 1 D of the targeted correction. They reported “predictable and stable” vision in all patients with no complications.
In a major Verisyse trial, after three years 84% of 231 people receiving the lens had 20/40 or better uncorrected vision with few complications reported and very limited endothelial cell loss.
A one-year interim analysis of the phase 3 trial of the Alcon AcrySof CacheT Phakic found that almost 96% of 161 patients were within 1 D of the targeted correction, with no instances of pupil ovalization, papillary block or retinal detachment.
In study after study, phakic IOLs score high in the area of patient satisfaction.
It is data such as this that is winning over surgeons and creating more advocates for phakic IOLs. With future advances just over the horizon and Alcon a potential new major player in the arena to create additional awareness, the future of phakic IOLs seems assured. But whether phakics remain primarily a niche offering or demonstrate an ability to expand their realm is still to be determined. OM