Phakic IOLs offer higher range of correction without bioptic approach

Cataract surgeons like phakic implants because they make use of familiar tools and techniques.

Issue: December 1, 2001

ByRochelle Nataloni

Refractive surgical implants, from phakic IOLs to corneal inlays and inserts, are expanding the scope of options for a range of myopic and hyperopic patients. Daniel S. Durrie, MD, said the main difference between the two types of refractive surgical implant is that cataract surgeons may feel more comfortable implanting phakic IOLs, while LASIK surgeons may be more inclined to offer corneal implants and inlays to their patients.

Among other differences, phakic IOLs can correct a higher range of refractive errors independently, while corneal inlays and implants must be used in combination with laser surgery for a “bioptic” approach to correct more than a few diopters of refractive error.

Rise of phakic IOLs

George O. Waring III, MD, professor of ophthalmology at Emory University School of Medicine and founding surgeon at the Emory Vision Correction Center in Atlanta, said there are at least five reasons why phakic IOLs will grow in popularity throughout the coming years. First, IOL technology has been around for half a century and every cataract surgeon knows how to implant an IOL.

“This is a comfortable approach for anterior segment surgeons, whereas with LASIK, surgeons have to learn how to use microkeratomes and lasers,” he said.

Second, he suggested, there is a practical imperative to incorporating phakic IOL technology into a practice.

“It is a lot easier for a surgeon who does 10 cataract surgeries in a day, and who wants to do refractive surgery, to stay in the same operating room with the same staff and the same setup and implant five phakic IOLs than it is for that surgeon to go across town to a refractive surgery center and have to deal with a whole complex set of negotiations and then still have the stress and strain of dealing with new microkeratomes and new lasers,” he said.

The third reason, according to Dr. Waring, is that the quality of vision is better with a phakic IOL in higher corrections (greater than –9 D and greater than +4 D) than it is with LASIK.

“The eye is put back in focus with LASIK, but optical aberrations increase because the shape of the cornea is changed. With phakic IOLs, the cornea is not changed, and its normal asphericity remains intact,” he explained.

He cited the study of Alaa M. El Danasoury, MD, in Abu Dhabi, of patients with a phakic IOL in one eye and LASIK in the other for myopia of –9 D to –15 D. Nearly all patients preferred the phakic IOL eye because of better quality of vision, even though the refractive outcome was the same in the two eyes.

The fourth reason for phakic IOLs’ bright future is that they are removable, Dr. Waring said.

“Many patients simply like the idea that the procedure can be ‘undone’ if they are not satisfied with their quality of vision,” he said.

Finally, phakic IOLs are adjustable while in the eye.

“They are adjustable in the sense that LASIK can be done over them. Bioptics is the ultimate combination because we are not thinning the cornea nearly as much as when we attempt the full correction with LASIK. In addition, phakic IOLs that have adjustable optics are in development,” he said.

What’s out there?

Although two phakic IOLs are deep into the approval process, none are yet available to patients in the United States outside of clinical trials. The Artisan (Ophtec USA, Inc.) is an anterior chamber lens that clips onto the iris. According to clinical investigator Edward E. Manche, MD, of Stanford University School of Medicine, the Artisan lens is in the final stages of phase 3 Food and Drug Administration trials. Nearly 600 have been implanted at 15 different sites, and the outcomes have been “quite impressive,” he said. It is indicated for –5 D to –20 D and +3 D to +12 D. Dr. Manche has implanted 30 of these lenses and has 100% of eyes seeing 20/40 or better and 60% seeing 20/20 or better in patients with an average correction of –14 D.

“One of the nice things about the procedure is the number of patients who are gaining lines of best-corrected acuity,” he said.

Approximately 35% of his patients have gained two lines of vision, and some are gaining three or four. No cataract formation has been seen with this IOL, he said.

Dr. Manche is also an investigator for the Medennium Phakic Refractive Lens (PRL), a silicone posterior chamber lens that was entering FDA phase 3 testing when this article was written. Approximately 200 have been implanted in the United States since 1996, he said.

“Aesthetically, the posterior chamber lenses look beautiful in the eye. Ophthalmologists are accustomed to seeing lenses in the posterior chamber,” Dr. Manche said. “The real question, of course, is what the complication rates are going to be. Are we going to see more cataracts with the posterior chamber lenses, which has been a problem with some of the early lens designs?”

The potential for endophthalmitis exists in any intraocular procedure, and implantation of phakic IOLs is no exception.

“That’s going to be a sobering point with these lenses,” he said. “Although I haven’t seen any endophthalmitis in the Artisan or Medennium trials, you have to consider that this is a relatively small cohort of approximately 700 eyes done by 20 meticulous surgeons under strict protocol. When they become FDA-approved and they are used widely, there will be a certain percentage of eyes that suffer from serious complications.”

The phakic IOL that is the farthest along on the road to approval is the posterior chamber STAAR Implantable Contact Lens (ICL ), which recently completed clinical trials on approximately 600 myopes, according to James Salz, MD. Dr. Salz is an investigator in the STAAR ICL hyperopia trials.

The next step for the myopia data is submission to the FDA of a premarket approval application. The most prominent advantage of phakic IOLs, according to Dr. Salz, compared to another option – clear lensectomy – is that the patient retains the ability to accommodate.

“Myopia really is where the greatest need exists for phakic IOLs,” Dr. Salz said. “With hyperopes, I don’t hesitate to do a clear lensectomy if they are really high, such as +10 D or +11 D, because they are happy to give up their accommodation for good natural vision. We don’t need the implant so much in those eyes, but there’s a real need for it in nearsighted eyes.”

Bausch & Lomb’s NuVita MA20 is an anterior chamber, angle-fixated phakic IOL that is popular in Europe, Asia and South America, according to Dr. Waring. However, he added that he believes the odds are slim that the company will seek approval of the NuVita lens in the United States, because it is already testing a foldable version of the lens that can go through a 3-mm incision, which is essentially half the size of the incision required for the MA20. The new lens is a hydrogel, anterior chamber, angle-fixated lens. It is currently being tested internationally, according to Dr. Waring.

“The main advantage of the hydrogel version is that it is foldable and will go through a small incision. With that smaller incision, we’re looking at conformity with cataract surgery,” he said.

The big question

The big question is whether phakic IOLs should be used for average myopic and hyperopic patients, or whether they should remain reserved for patients who are outside the bounds of LASIK surgery. Dr. Durrie said if one considers the evolution of refractive surgery, phakic IOL implantation may eventually be a choice for correcting moderate and even low refractive error.

“If you review the development of RK, PRK and LASIK, they all have something in common. They were all initially used for high myopes, “ he said. “When we started with RK in the 1970s, we were doing —10s and –12s, attempting to make them into –4s. We didn’t ever consider offering it to a patient who didn’t have a lot of nearsightedness. Over the years, we found out that it was pretty safe, and we started doing lower and lower myopes, and eventually it was done for –1s, –2s and —3s.

“Likewise, when LASIK came along, it was only for people who were out of the range of PRK. Eventually, as surgeons got comfortable with it, we would go all the way down even to —0.5 D. So if phakic IOLs ... follow this trend, once surgeons are comfortable with it, they will start using it for routine refractive surgery.”

For Your Information:

Daniel S. Durrie, MD, can be reached at Hunkeler Eye Centers, 5520 College Blvd., Overland Park, KS
66211; (913) 491-3737; fax: (913) 491-9650; e-mail: ddurrie@novamed.com. Dr. Durrie is a paid consultant for Ophtec and Bausch & Lomb.

George O. Waring III, MD, can be reached at Emory Vision Correction Center, 875 Johnson Ferry Rd. NE, Atlanta, GA 30342; (404) 250-9700; fax: (404) 250-9006; e-mail: georgewaring@emoryvision.com. Dr. Waring is a paid consultant for Bausch & Lomb.

James Salz, MD, can be reached at 444 South San Vicente, Ste. 704, Los Angeles, CA 90048; (310) 657-0300; fax: (310) 657-1719; e-mail: jjsalzeye@aol.com. Dr. Salz has no direct financial interest in the products mentioned in this article, nor is he a paid consultant for any companies mentioned.

Edward E. Manche, MD, can be reached at 300 Pasteur Dr., Suite A-175, Stanford, CA 94305; (650) 723-5517; fax: (650) 498-6488. Dr. Manche has no direct financial interest in the products mentioned in this article, nor is he a paid consultant for any companies mentioned.

For information on the Artisan phakic IOL, contact Ophtec USA, 6421 Congress Ave., Suite 112, Boca Raton, FL 33487; (561) 989-8767; fax: (561) 989-9744; e-mail: ophtecusa@aol.com; Web site: www.ophtec.com.

For information on the PRL phakic IOL, contact Medennium Inc., 15350 Barranca Parkway, Irvine, CA 92618; (949) 789-4907; fax: (949) 789-9032; e-mail: info@medennium.com; Web site: www.medennium.com.

For information on the ICL, contact STAAR Surgical, 1911 Walker Ave., Monrovia, CA 91016; (818) 303-7902; fax: (818) 358-9187.

Bausch & Lomb can be reached at 555 West Arrow Hwy., Claremont, CA 91711; (800) 423-1871; fax: (909) 399-1525.