This article is more than 5 years old. Information may no longer be current.
Phakic IOLs an alternative for high myopes; new technologies emerging
With two phakic IOLs now available to U.S. surgeons and more on the way, experts speak about surgical techniques, complications and the future.
Click Here to Manage Email Alerts
Phakic IOLs offer a refractive surgical option for high myopes whose refractive errors fall outside the treatment range for LASIK. U.S. surgeons have now had 2 years’ experience with the Verisyse lens from Advanced Medical Optics and 6 months’ experience with the Visian ICL from STAAR, and two more phakic IOL models are either in trials for regulatory approval or on track to begin soon.
| John A. Vukich |
With the number of options for phakic IOL implantation increasing, Ocular Surgery News spoke to experienced surgeons about their techniques, their tips on how to avoid and manage complications and their views on the future of phakic IOLs.
“Looking at phakic IOLs as a good choice for patients who fall out of bounds for LASIK is, I think, doing everyone a service,” said John A. Vukich, MD.
Dr. Vukich spoke to OSN about his experience implanting the Visian ICL. George Beiko, MD, FRCS, and Gregory Pamel, MD, spoke about Advanced Medical Optics’ Verisyse IOL (available in some countries from Ophtec as the Artisan lens) and AMO’s foldable Veriflex IOL, which is expected to begin U.S. clinical trials soon. OSN also spoke to Vance M. Thompson, MD, who has implanted both the Verisyse and the ICL, and to W. Andrew Maxwell, MD, PhD, who is investigating Alcon’s AcrySof Phakic IOL.
Preop assessment
As with any refractive surgical procedure, patient selection is vital for success with phakic IOLs, surgeons we interviewed said. Appropriate candidates for phakic IOLs are generally those who fall outside the range of correction for LASIK or who are otherwise unsuited for a corneal surgical procedure.
“What qualifies them really is that they’re highly myopic,” Dr. Vukich said. “What makes a patient choose a phakic IOL and the factors that will drive the decision are based on what is the medically appropriate and best choice for them.”
The screening tools used to identify candidates LASIK can also help to recognize candidates for phakic IOLs, Dr. Vukich said.
“In a complete refractive practice, phakic IOLs fit in very nicely, in that the same assessment of a LASIK patient is appropriate for a phakic IOL,” he said.
Dr. Thompson added, “We always make sure before we start educating them on phakic IOLs as an option that they’re good candidates for the procedure.”
Dr. Vukich said factors that might make a patient unsuitable for LASIK but potentially appropriate for a phakic IOL include inadequate or questionable corneal structure, atypical topography, corneal irregularities or astigmatism, dry eyes or other surface disease.
In addition, a candidate must have a deep anterior chamber, which Dr. Thompson defined as 3.2 mm or greater, and a good endothelial cell count, which he defined as 2,200 cells/mm2 or greater.
Dr. Thompson said immersion A-scan and the Carl Zeiss Meditec IOLMaster are the most accurate methods of measuring anterior chamber depth. He recommended that surgeons considering adding phakic IOL implantation to their practices should obtain a specular microscope for performing endothelial cell counts.
“Most intraocular surgeons already have an IOLMaster or immersion A-scan,” Dr. Thompson said, “but not all of them check cell counts. You have to if you’re going to do quality phakic IOL work.”
Corneal topography is another important factor in preop assessment of phakic IOL candidates. Most of the physicians we interviewed said they use either the Bausch & Lomb Orbscan or the Oculus Pentacam to screen for healthy corneal topography.
“We like to document that it’s a clean optical system before we’re going to do a phakic implant,” Dr. Thompson said.
He also noted that the Visante OCT anterior chamber imaging system from Carl Zeiss Meditec can be helpful to examine the position of the iris-lens diaphragm.
“If you see an iris-lens diaphragm that’s bulging forward, the patient has a fat lens, which could be an early cataract or could mean they just have a big lens,” Dr. Thompson said. “These people tend to do less well with phakic implants.”
Verisyse implantation pointers
The Verisyse phakic IOL has been implanted in patients for more than 2 decades around the world. This long-term experience was cited by Drs. Pamel and Thompson as a factor in their choice of lenses.
|
Image: Beiko G |
Dr. Pamel said another factor in his choice of the lens is that it is implanted in the anterior chamber.
“The surgeon can visualize the position of the implant at all times,” he said. “I know exactly where it is in relationship to the cornea and in relationship to the natural lens of the eye.”
The rigid PMMA IOL is inserted through a relatively large incision, usually around 6.2 mm, and attached to the iris with haptics in a procedure called enclavation. It is available with a 5-mm or a 6-mm optic.
“It’s important to measure pupil size and try and use the largest optic with respect to the pupil size that you can,” Dr. Pamel said, in order to avoid glare from the lens edge. He said he would recommend a lower refractive correction and opt for LASIK rather than risk glare in a patient with pupils that are too large.
The physicians said they use peri-bulbar anesthesia for implantation of the Verisyse.
“I always do peribulbar anesthesia,” Dr. Thompson said. “When you’re attaching something to the iris, it hurts because the iris is a sensitive structure.”
The incision for the Verisyse phakic IOL is larger than that for most cataract IOLs, but the physicians who spoke to OSN said this can be useful in patients with significant astigmatism.
“It’s a little larger incision. I can use that to my advantage if they have an astigmatism by operating on the steep axis of the astigmatism,” Dr. Thompson said. “I can lessen the astigmatism and take care of the myopia all at once, so it has a beneficial effect.”
Dr. Thompson said he uses Budo forceps from Ophtec to place the phakic IOL into the anterior chamber.
“They’re broader on the bottom and narrower on top,” he said. “That broad base helps so that when you grab the implant, it doesn’t have a tendency to tilt either way.”
Dr. Thompson said he uses the tip of a viscoelastic cannula to rotate the lens into position.
“If the chamber narrows or shallows a little bit, I can inject a little more viscoelastic while I’m rotating the lens,” he said.
The next step is enclavation of the haptics into the iris. Although there is no standard for how much iris to enclavate, Dr. Thompson suggested about 1 mm of tissue: “More than that is too much; less than that, you risk traumatic dislocation,” he said.
Dr. Pamel said the surgeon should be able to see that the haptics are securely around the iris tissue. He warned, “It’s better to err on enclavating more tissue than less tissue. I’ve had to re-enclavate patients when there was probably not enough iris tissue in the beginning.”
Dr. Beiko described a modified technique for Verisyse implantation that he developed to reduce the size of the external wound. He creates a 3-mm limbal incision and adds to that another 3 mm incision that goes back perpendicularly from the limbal incision through conjunctiva and sclera. He tunnels into the cornea from the 3 mm limbal incision and also tunnels underneath the sclera and into the cornea at a diagonal for another 3 mm from the scleral incision. This creates a flap incorporating both sclera and cornea that is 6 mm in length. Then the incision is extended into the anterior chamber, so there is 3 mm exposed and 3 mm underneath the scleral-corneal flap.
Describing the incision, Dr. Beiko said, “This decreases the size of the external wound and removes the need for putting in sutures, speeds up healing and decreases the amount of astigmatism.”
Dr. Beiko said MicroSurgical Technology has designed a set of forceps for him that are made for grasping the iris and lifting it into the haptics.
“The forceps can be inserted through a 1.2-mm paracentesis. They are similar to the MST capsulorrhexis forceps, but they’re designed not to damage the iris,” he said.
Dr. Thompson advised placing the IOL slightly inferior, as the lens has a tendency to move superiorly after enclavation.
“If you start with the lens perfectly centered before you enclavate, it’s going to end up decentered superiorly,” he said. “We like to have it start slightly inferior, and then when it’s enclavated, centration should be right where we want it.”
Visian ICL implantation pointers
The Visian ICL offers surgeons a more familiar implantation procedure, much like current cataract procedures, users told OSN. The lens has been in use outside the United States for 10 years.
| Vance M. Thompson |
“The ability to use topical anesthetic routinely, the ability to use a small-incision, self-healing technique which is consistent with our current cataract technique, the fact that it is an injectable implant and it is more consistent with modern surgical technique inasmuch as we don’t require corneal suturing – those are all things that drive our decision toward the Visian ICL,” Dr. Vukich said.
Dr. Thompson said he recently added the Visian ICL to his practice because it offers a slightly wider range of correction for myopic patients.
“Sometimes I need to use it,” he said. “I think it’s a quality product, and as I get more and more comfortable with it I may use it more and more.”
Dr. Vukich said most surgeons should quickly feel comfortable working with the Visian ICL because of the procedure’s similarity to cataract surgery. The ICL is injected into the anterior chamber and then positioned posterior to the iris using an ICL manipulator, he explained.
“It’s basically a modified spatula that allows the implant to be positioned within the anterior segment into the ciliary sulcus,” he said.
Since the incision is smaller, no sutures are needed to close it.
Dr. Thompson noted that care must be taken to avoid trauma, both to the natural lens and to the implant. The ICL must be handled with care in order to preserve its surface, he said.
“You don’t want to go over the ICL, you don’t want to touch it because the optic, the lens membrane is very delicate,” Dr. Thompson said. “You don’t want to traumatize the crystalline lens and you don’t want to traumatize the optic of the ICL.”
Preventing complications
The surgeons we interviewed said phakic IOLs are safe, but with surgery there is always the possibility for complications. They spoke about obstacles a surgeon physician may face and how to avoid them.
Because pupillary block is a possible complication with either approved lens, Dr. Thompson said the surgeon must always perform a peripheral iridotomy prior to surgery.
“I usually do it with a YAG laser before I take them to the operating room,” he said. “With the Verisyse, I do it the day of the surgery. With the Visian, the company recommends a couple weeks preop for the peripheral iridotomy.”
Decentration of the Verisyse can increase the possibility of glare and halos at night when the pupil dilates. Dr. Pamel suggested looking at the lens through both the surgeon’s microscope and the assistant scope “just to check various angles of the implant to ensure adequate centration.”
Cataract formation can occur due to trauma to the crystalline lens with either lens, surgeons said.
The crystalline lens should be treated with as much care as the corneal endothelium during implantation, if not more, Dr. Vukich said.
Dr. Thompson agreed. He said extra care is needed regarding intraocular structures during phakic IOL surgery.
“Even though in cataract surgery we’re gentle, you want to be another level of gentle when you’re doing phakic implant surgery,” he said. “These are younger folks who are going to live with the results of this surgery, and if you knock off endothelial cells or create lens trauma, this patient’s going to live with that complication a long time.”
Future phakic IOLs
The Alcon AcrySof Phakic is an anterior chamber angle-fixated lens made of the same material used in the AcrySof cataract lens implants, Dr. Maxwell said. The lens is currently in clinical trials in the United States for FDA approval.
“The benefit of this lens implant is the fact that it is a foldable lens implant that can be placed through a 3-mm to 3.2-mm incision,” Dr. Maxwell said. “It is a lens implant that in the clinical trial has shown excellent efficacy and excellent safety profile.”
Dr. Maxwell said the AcrySof Phakic can go through a smaller incision than the Verisyse, and implantation procedure is less complicated than for either of the approved phakic lenses.
“The simplicity of the implantation and the ease of the procedure I think will be a significant benefit,” he said. “It uses the Monarch II injection system, which is the same system that doctors are familiar with for doing lens implants with the AcrySof in cataract patients.”
AMO is developing the Veriflex, a foldable version of the already-approved Verisyse phakic IOL, Dr. Pamel said.
“We anticipate that it’s going to come to clinical trial within the next 6 months,” he said. “I have seen it implanted, and I’ve seen clinical results, and they’re comparable to the regular Verisyse. … It will offer a smaller incision size, the potential for less astigmatism induction and faster recovery.”
Dr. Beiko, who has implanted the Veriflex, said a special spatula is used to hold the lens and introduce it into the anterior chamber through a 3.2-mm incision.
Advice
The surgeons who spoke to OSN for this article had some advice for surgeons considering adding phakic IOL implantation to their refractive surgical practices.
Dr. Beiko recommended that surgeons examine the available technologies and make their decisions after a thorough investigation.
“Go with the technology that’s been proven and been around for a while for their initial cases so they get familiar with the techniques,” Dr. Beiko said. “Explore more recent technologies later, once there is a comfort level with the surgery and possible complications.”
Appropriate training is the next step.
“Become certified and trained in this technique,” Dr. Vukich said. “Once that familiarity is developed, most surgeons will be comfortable with this for a broad spectrum of patients, not just limited to the high myopes or the patients who have other issues.”
For more information:
- John A. Vukich, MD, can be reached at the Davis Duehr Dean Center for Refractive Surgery, 1025 Regent St., Madison, WI 53715; 608- 282-2000; fax: 608-282-2000. Dr. Vukich has no direct financial interest in the products mentioned in this article. He is a paid consultant for STAAR Surgical.
- George Beiko, MD, FRCS, can be reached at 180 Vine St., Suite 103, St. Catharine’s, ON L2R 7P3 Canada; 905-687-8322; fax: 905-687-8766.
- Gregory Pamel, MD, can be reached at 115 East 61st St. #1B, New York, NY 10021; 212-355-2215; fax: 212-355-6930.
- Vance M. Thompson, MD, can be reached at Sioux Valley Clinic, Talley Building, 1310 W. 22nd Street, Sioux Falls, SD 57105; 605-328-3937.
- W. Andrew Maxwell, MD, PhD, can be reached at 1360 E. Herndon, Suite 401, Fresno, CA 93720; 559-449-5010; fax: 559-449-5014.
- Katrina Altersitz is an OSN Staff Writer who covers all aspects of ophthalmology.