Phakic IOLs need customized approach, high-precision measurements

At the ESCRS Winter Refractive Surgery Meeting, surgeons discussed advantages, disadvantages and results of phakic IOLs.

ByMichela Cimberle

ROME – As follow-up time becomes longer, phakic IOL technology is gaining credibility, according to surgeons experienced with the lenses. Different types and models, each one with specific features, are proving to be safe, with stable results, easy-to-treat complications and the advantage of being a reversible procedure.

Spotlight on IOLs

However, successful phakic IOL treatment depends on three important points — patient selection, IOL choice and adequate sizing. These issues were repeatedly emphasized by speakers during a symposium on phakic implants held at the ESCRS Winter Refractive Surgery Meeting.

“If we look behind many failures, we’ll see that it’s not the lens’ fault but our fault for not respecting indications, contraindications, correct procedures and criteria,” said Camille Budo, MD.

Selecting patients and lenses

Joseph Colin, MD, emphasized that phakic IOLs are not a surgical option for all patients.

“They are and will remain a niche market, addressing a fairly low percentage of refractive surgery candidates, consisting of very high myopes and selected hyperopes,” he said.

But for this limited population, they are “an excellent option that offers considerable advantages over both laser refractive surgery and refractive lensectomy,” Dr. Colin said.

It should be emphasized that “one phakic IOL doesn’t fit all eyes,” Emanuel S. Rosen, FCOphth, said. Surgeons should build experience with different types of phakic IOLs to avoid the mistake of using just one type of lens for all patients.

According to Thomas Kohnen, MD, phakic IOL choice should be based on refraction, age of the patient and anatomy of the eye. Knowing the potential complications of each lens is crucial because “visual results are comparable, but complications make the difference,” he said.

Measurements

Measuring the anterior chamber in all possible dimensions is necessary when choosing a phakic lens, according to Georges Baikoff, MD.

“Long-wavelength ultrasound devices such as the Carl Zeiss Meditec Visante OCT can precisely measure the anterior chamber depth and diameter, evaluate the symmetry of the chamber and calculate the safety distance of the IOL from the crystalline lens and the corneal endothelium,” he said.

Using this technology, researchers have learned that in most cases the anterior chamber diameter is larger on the vertical axis than on the horizontal axis, Dr. Baikoff said. In other words, the anterior chamber is an oval, and the size of angle-supported lenses should be calculated on the longer axis; otherwise, the lens will rotate, he said.

Special software can specify the threshold for a safe lens vault in respect to the endothelial cell layer, he said.

“We must also take into account that the anterior pole of the crystalline lens moves forward by about 20 µm per year, and the space between crystalline lens, IOL and corneal endothelium gradually becomes narrower. These changes over time have to be considered when implanting a phakic lens, and patients should be told that the implant will not be there forever,” Dr. Baikoff said.

Kelman Duet

The Kelman Duet (Tekia) is an angle-supported lens with independent PMMA haptics and frame, and a third-generation silicone optic. This lens comes in two separate pieces that are assembled inside the eye, and it has several advantages, according to Jorge L. Alió, MD, PhD.

“If it is over- or undersized, you may decide to change the haptic, leaving the optic inside. On the other hand, when the patient becomes presbyopic, you may decide to change the optic with a presbyopic optic without removing the haptic,” he explained.

Dr. Alió said that it is “quite a new type of surgery because we are not used to assembling pieces inside the eye. However, after a few times it becomes not only feasible but very easy.” Once the haptic part is inserted through a 2- to 2.5-mm incision, the eye is filled with cohesive viscoelastic and iridectomy is performed. The foldable optic is then injected in the eye and engaged to the two anchor points in the vertical axis of the haptics.

GBR Vivarte

Patient selection based on the precise measurement of the width and depth of the anterior chamber is necessary with the GBR Vivarte from IOLTech, according to Fabrizio Camesasca, MD.

“The IOL Master (Carl Zeiss Meditec) has changed our approach to this surgery and allows us to identify eyes that are out of range for this type of IOL,” he said.

He added that intraoperative measurement with a surgical sizer should be performed.

“If the lens has the right length and the tissue-to-lens clearances are ensured, complications can be avoided,” Dr. Camesasca said. “In our series of 34 eyes, we had three cases develop progressive endothelial cell count reduction, which required explantation of the lens. Probably selection in these patients had not been as accurate as desirable.”

Artisan/Verisyse, Artiflex

More than a decade after its introduction, the Artisan/Verisyse lens (Ophtec/Advanced Medical Optics) is still going strong. Fourteen years after implantation, visual results in 40 eyes are stable, according to Dr. Budo.

“Patients are still emmetropic and satisfied, and endothelial cell loss is 2.5%,” he said. Dr. Budo said that this lens could potentially have no complications if indications and contraindications are followed and if surgery is performed correctly.

The more recent foldable version of the Artisan, the Artiflex (Ophtec), seems to have equally good results. Like the Artisan, it has the advantage of being a one-size-fits-all model.

“You don’t have to bother about measuring the anterior chamber width, and the lens is always perfectly centered on the pupil, independent of whether the pupil is eccentric or not,” said Antonio Marinho, MD.

A toric version of the Artisan/Verisyse lens needs additional care and accuracy during implantation, according to José Güell, MD.

“Being a toric lens, it is mandatory to position it with extreme precision, and this largely depends on the amount of iris tissue you enclavate. If you think the lens is not well-orientated, do not hesitate to take the iris out of the claw and start again,” he said.

Sutures are a critical part of a successful procedure, as they need to be astigmatically neutral.

Acriol

In the age of foldable implants, the Acriol from Soleko depends on the advantages of traditional rigid PMMA material, one surgeon said.

“I deliberately didn’t want a foldable lens because I think that the disadvantages of phakic foldable implants outweigh their advantages,” said Albino Rapizzi, MD, who developed the lens 3 years ago. “Even though the incisions are smaller, when you introduce a lens that is rolled up, you create a round opening that easily lets the viscoelastic flow out with consequent flattening of the anterior chamber. Also, when the lens unfolds in the eye, it inevitably produces some contact with the endothelium and the iris.”

Icare

Dr. Sourdille also discussed complications reported about the Icare lens (Corneal). Most complications reported in 1,400 eyes implanted in Europe with this lens were related to sizing, he said.

“We had 10 cases of endothelial problems, mostly due to undersizing, and 10 cases of pupil ovalization, due to oversizing,” he said.

Dr. Sourdille said the geometry of the Icare is designed to minimize these problems.

ICL, PRL

Posterior chamber IOLs have evolved throughout the years, and problems such as the risk of secondary cataract have been minimized, speakers said.

For posterior chamber IOLs, “adequate sizing is 99% of the job,” Carlo Lovisolo, MD, said. Compared to previous models, the Visian ICL (STAAR Surgical) has reduced the risk of secondary cataract to 1%, as shown by results of Food and Drug Administration trials.

A lens that is too small and has a low vault height might interfere with the natural flow of aqueous between the IOL and the human lens and produce cataract in the long term. On the other hand, a lens that is too long induces excessive vault, which may cause the iris to bulge forward with the risk of closing the angle. Software developed by Dr. Lovisolo (the Lovisolo phakic IOL sizer, Ultralink) provides 3-D simulations of a phakic lens implant in the patient’s anterior segment.

The posterior chamber PRL implant (IOLTech) is designed to be independent of intraocular support and to float in the aqueous over the crystalline lens. This design has the advantage of being one size and easier to implant. However, inconsistent visual results and complications due to the potential instability of the lens are a concern, said Bo Philipson, MD.

“Now that more than 7,000 of these lenses have been implanted in Europe with a follow-up that is long enough to draw some conclusions, we can say that visual results are very good and stable, and the complication rate is quite low,” Dr. Philipson said.

For Your Information:

Jorge L. Alió, MD, PhD, can be reached at Vissum, Instituto Oftalmologico de Alicante, Avda. de Denia, s/n, 03016 Alicante, Spain; +34-965-150-025; fax: 34-965-151-501; e-mail: jlalio@vissum.com.

Georges Baïkoff, MD, can be reached at Clinique Monticelli, 88 Rue du Commandant Rolland, 13008 Marseille, France; +33-04-91-162223; fax: +33-04-91-162225; e-mail: g.baik.opht@wanadoo.fr.

Camille Budo, MD, can be reached at Sint-Godfriedstraat 8 (Sint Truiden), Melveren 3800, Belgium; +32-11-689684; fax: +32-11-688286; e-mail: camille.budo@skynet.be.

Fabrizio Camesasca, MD, can be reached at Istituto Clinico Humanitas, Rozzano-Milan, Italy; +39-02-8224-2311; fax: +39-02-8224-4691; e-mail: fabrizio.camesasca@humanitas.it.

Joseph Colin, MD, can be reached at Hôpital Pellegrin, Place Amélie Raba-Lèon, 33076 Bordeaux, France; +33-5-56795608; fax: +33-5-56795909; e-mail: joseph.colin@chu-bordeaux.fr.

José Güell, MD, can be reached at I.M.O., c/Munner 10, 08022 Barcelona, Spain; +34-93-2531500; fax: +34-93-4171301; e-mail: guell@imo.es.

Thomas Kohnen, MD, can be reached at Klinik für Augenheilkunde, Johann Wolfgang Goethe Universität, Theodor Stern Kai 7, D 60590 Frankfurt am Mein, Germany; +49-69-63013945; fax: +49-69-63013893; e-mail: kohnen@em.uni-frankfurt.de.

Carlo F. Lovisolo, MD, can be reached at via Cusani, 7-9, 20121 Milano, Italy; +39-02-8057388; fax: +39-02-86452896; e-mail: loviseye@fastwebnet.it.

Antonio Marinho, MD, can be reached at R. Eugenio De Castro 170/41, Porto 4100, Portugal; +351-222007538; fax: +351-226093345; e-mail: marin@mail.telepac.pt.

Bo Philipson, MD, can be reached at Eye Clinic, Sophiahemmet Stockholm S-11486, Sweden; +46-8-21-86-80; fax: +46-8-20-82-81; e-mail: bo@philipson.org.

Albino Rapizzi, MD, can be reached at Centro Laser Veneto, Via De Carlo 1, 31100 Treviso, Italy; +39-0422-422492; fax: +39-0422-424350; e-mail: albino.rapizzi@tin.it or claser@tin.it.

Emanuel S. Rosen, FCOphth, can be reached at 33 George St., Wakefield, Yorkshire WF1 1LX, United Kingdom; +44-161-848-1500; fax: +44-161-848-1519; e-mail: erosen5640@aol.com.

Philippe Sourdille, MD, can be reached at Le Chaigne, 16120 Touzac, France; +33-630-362-846; fax: +33-252-83-87-19; e-mail: philippe.sourdille@wanadoo.fr.

Michela Cimberle is an OSN Correspondent based in Treviso, Italy.