Toric IOLs mark latest technological advance

As part of our Spotlight on IOLs, OSN presents the latest news in IOL technology from the ESCRS/Winter Refractive Surgery Meeting.

BARCELONA – Until recently, for cataract patients with astigmatism, successful cataract surgery was only half the battle for regaining quality of vision. Toric IOLs – another step forward in the direction of refractive cataract surgery – now have the capability to offer these patients complete visual rehabilitation, eliminating the need for additional correction with spectacles or contact lenses or additional procedures such as astigmatic keratectomy or limbal relaxing incisions.

Approximately 20% of the patients presenting for cataract surgery have a clinically significant degree of pre-existing astigmatism. Its prevalence increases with age, and the axis tends to rotate to against-the-rule, as demonstrated by a multicenter study carried out in Italy, Belgium and Spain and presented in a poster at the European Society of Cataract and Refractive Surgeons winter meeting by I. Antico, R. Nicoletti, C. Fabiani, S. Barile and J.J. Perez-Santonja.

Keratometry was performed in 1,000 eyes of 500 patients scheduled for cataract surgery. The correlation between age and astigmatism was evaluated with a trend test.

“Mean cylinder power was found to increase with age,” the authors said. “In addition, we found a correlation between age and the prevalence of against- the-rule astigmatism or oblique astigmatism, which were respectively 60% and 28% of the total astigmatic cases.”

Various options

Case series on toric lenses were presented by several speakers at the meeting.

The acrylic Alcon AcrySof toric IOL, approved by the U.S. Food and Drug Administration in 2005, is a single-piece acrylic lens, structurally identical to the classic Acry-Sof but with a toric component on the posterior surface of the optic. Three models, with 1.5 D, 2.25 D and 3 D of cylinder correction, are available.

The AcrySof Toric IOL was the most widely represented lens in the number of case series presented at the meeting.

The Rayner T-flex IOL is also made of hydrophilic acrylic material. It has a large optic diameter of 6.25 mm and an overall length of 12.5 mm. It is available in a range of cylinder and sphere combinations, for a wide astigmatic range between 1 D and 11 D.

More advanced concepts are also taking shape. The new toric Acri.Lisa from Acri.Tec combines multifocality and astigmatic correction, and the toric version of Marie-Jose Tassignon’s BIL (bag-in-lens) IOL reduces the chances of misalignment and decentration.

New tools for astigmatic correction

“We were very excited when we were offered toric IOLs in 2006 because we saw there a possibility for correcting astigmatism at the same time of cataract surgery. We now use this lens in about 50% of our cataract procedures, and it has been to us a real change in the quality of our results,” said Margaret Kearns, MD, who runs a private practice with her husband, Richard Smith, MD, in Sydney.

She reported the results of 144 consecutive eyes implanted with either the toric AcrySof T3, T4 or T5 or the Rayner T-flex, according to the degree of astigmatism. Preoperative measurements were taken with the Orbscan (Bausch & Lomb), the IOLMaster (Carl Zeiss Meditec) and the Pentacam (Oculus) in some cases, and the toric IOL was implanted only if the amount of astigmatism on the Orbscan was more than 0.75 D.

After the operation and implantation of the lens, the final refractive cylinder was 0.5 D or less in 88% of the patients. Ninety-one patients had 0 D of cylinder, 36 were between 0.5 D and 0.25 D, nine had 1 D, and only one case had 1.5 D.

“The performance of both these lenses is excellent,” Dr. Kearns said. “We now do very few laser enhancements. In this case series we did only four PRK enhancements for low residual refractive errors.”

Preliminary results with the Rayner toric IOL were also reported in a poster by a team of Spanish ophthalmologists. O. Pujol, D. Nahra and O. Giralt, of Hospital de l’Esperança in Barcelona, reported that a follow-up of 12 months showed a reduction of astigmatism in 100% of eyes and a rotation angle that did not exceed 10°.

The authors concluded that “Rayner toric intraocular lenses provide a considerable improvement in visual acuity and excellent rotation stability.”

Toric IOL case series

Between May 2006 and September 2007, 53 consecutive cases were implanted with T3, T4 or T5 models of the AcrySof Toric at Maastricht University Hospital in the Netherlands by Rudy Nuijts, MD, and Noël Bauer, MD. Patients with regular corneal astigmatism from 1 D to 6 D were included and divided into three groups. The T5 group of 13 eyes had corneal cylinder exceeding the power of the lens, and a partial astigmatic correction was intended.

“The procedure is much like a standard cataract procedure with only three small variations: toric IOL calculation, marking of the eye and IOL alignment,” Dr. Bauer said.

IOL-related rotation proved to be limited with the AcrySof toric lens, “smaller than 1° in 70% of the eyes,” Dr. Bauer said.

Toric mix-and-match for amblyopia

Gerd Auffarth

Tanja M. Rabsilber, MD, and Gerd U. Auffarth, MD, presented preliminary results with the Acry-Sof Toric lens in 18 eyes of 12 patients implanted at Heidelberg University Hospital, Germany. They found that the lens provides “good functional results, with only low residual cylinder values.” The difference between target and achieved astigmatic correction was ±0.5 D in 91% of the eyes and ±0.25 D in 45% of the eyes. All patients achieved good uncorrected vision, and no postoperative rotation of the lens was reported.

At the same institution, a toric and multifocal IOL mix-and-match method was used in five amblyopic patients between the ages of 52 and 63 years.

“Astigmatism is often found in amblyopic patients. Following uncomplicated lens removal, we implanted an AcrySof Toric lens in the amblyopic eye and a multifocal Alcon ReSTOR in the fellow eye,” Andreas Borkenstein, MD, said.

Results were encouraging.

“Implanted with the toric lens, the amblyopic eyes performed very well, achieving a good distance vision in all cases. With the multifocal lens implanted in the dominant eye, a good binocular performance for distance acuity was achieved in all the patients,” he said.

Alignment with toric lenses

Results with the STAAR Surgical toric IOL were reported by Joseph Ma, MD, of the University of Toronto.

He presented a retrospective review of 147 eyes of 102 astigmatic patients who underwent cataract surgery. A STAAR toric IOL was implanted in 93 of these eyes, while the remaining eyes received an AcrySof toric lens.

“The STAAR toric provides excellent correction of astigmatism. No lines of BCVA were lost, and three patients with keratoconus had a significant improvement in uncorrected vision,” he said.

Compared with the AcrySof, the STAAR lens is able to correct a higher degree of astigmatism. However, Dr. Ma noted, “it requires larger incisions and has less rotation stability.” Three of the lenses in this case series required repositioning due to a significant postoperative rotation.

Dr. Ma emphasized the importance of correct alignment of toric lenses in respect to the astigmatic axis and proposed a new one-step procedure that improves accuracy.

The epithelium is marked with a 30-gauge needle at the slit lamp, using a Haag-Streit eyepiece, which has a built-in leveler and a reticle in the form of concentric circles that allows the surgeon to position the marking exactly in the center of the visual axis.

“This can be adjusted to the angle of your topographer or whatever device you use to determine the axis of the astigmatism, and then you can line it up concentrically with the pupil so you mark exactly where the marks are on your lens,” Dr. Ma explained.

With a toric lens, markings are usually between 6 mm and 4 mm, which is the same size of the larger concentric circle.

“These marks are easily visible, sharp and precise on the surgical microscope, and since you know exactly where the marks on your lens are going to be, you can superimpose epithelial markings on the lens markings,” he said.

Bifocal toric IOL

The challenge of treating cataract and correcting myopia, presbyopia and astigmatism in a single lens-based procedure has been pursued by Acri.Tec with the new bifocal toric Acri.Lisa. This IOL, which is made of hydrophilic acrylate with hydrophobic surfaces, is a biconvex diffractive multifocal lens, with a diffractive aspheric back surface and aspheric toric front surface.

The toric Acri.Lisa also addresses the issue of surgically induced astigmatism, which can be a problem when patients are implanted with multifocal IOLs.

“Implantation can be performed through a small 1.5-mm to 1.6-mm incision with no induction of astigmatism at all,” said Detlev Breyer, MD, of Düsseldorf Eye Clinic, Germany, who presented his first results with this lens.

“I perform the incision with an Acri.Tec diamond knife and use a coaxial phacoemulsification technique, which I prefer to bimanual MICS,” he said.

He recommended a well-centered capsulorrhexis of at least 6 mm to avoid any decentration.

Before surgery, he marks the eye with a HumanOptics marker, which he said is an accurate instrument.

“First results are very promising even in patients with high astigmatism and myopia or even after keratoplasty procedures,” Dr. Breyer said. “The patients’ subjective impression is very good for both near and distance vision.”

Prototype BIL

Marie-José Tassignon, MD, announced that the first prototype of the new toric BIL (Bag-in-the-Lens) IOL, which she developed a few years ago, was to be implanted in one patient at the end of March.

The BIL has a unique design, with two round haptics surrounding the optic, and thus a unique technique of implantation, in which both the anterior and the posterior capsules are positioned inside the fine groove that lays in between the haptics.

“If we have a stable lens, well-centered, according to the best optical system of the eye … it is quite obvious that we can start with a toric model,” she said.

Different strategies with multifocal IOLs

Multifocal IOLs are an expanding surgical option. They are used in cataract surgery and clear lens extraction with the aim of providing near and intermediate vision as well as maintaining or improving distance UCVA. Both types of multifocal IOLs, diffractive and refractive, have advantages and disadvantages, and neither of them is an easy option for all patients. They require a variable amount of time for brain adaptation and may cause problems of halos and diffractive phenomena in some patients.

Mix-and-match, or custom match, techniques are gaining popularity as an alternative procedure to bilateral implantation of the same lens, based on the principle that the combination of two different multifocal IOLs reciprocally compensates the weak points of single IOL models. The lenses work synergistically, increasing depth of focus and visual quality at all distances and minimizing photic phenomena.

Key points for success

Multifocal IOLs require a completely different and more individual approach to the patient, according to OSN Europe/Asia-Pacific Edition Associate Editor Matteo Piovella, MD, of CMA microsurgery center in Milan, Italy.

Matteo Piovella

“You need to spend more time with your patient preoperatively, in between the two consecutive procedures, and in the follow up,” he said.

The first key point for a successful procedure is an accurate preoperative examination, which consists of three basic steps: measuring the pupil in mesopic conditions, establishing eye-dominance and performing biometry with two different methods: manual and automated with the IOLMaster (Carl Zeiss).

A large pupil size of more than 5.2 mm is already an exclusion criterion for mix-and-match, as these eyes would inevitably perceive night halos with a multifocal lens. Another exclusion criterion is the absence of the eye-dominance parameter.

“There are patients who don’t have a dominant eye and use both eyes much in the same way. If they are used to this peer-relationship between eyes, they will never adapt to two different lenses,” he noted.

In the potential candidates for mix-and-match, Dr, Piovella begins by implanting the Tecnis multifocal IOL (Advanced Medical Optics) in the non-dominant eye. Tecnis is a diffractive lens, and is therefore less likely to cause halos. Surgery in the second, dominant eye is planned one week later, which gives the patient enough time to adjust to the new implant and report his/her reaction in terms of possible visual disturbances.

“If the patient shows to be sensitive to halos and reports severe discomfort in night vision, we implant another Tecnis, because he or she would certainly not stand the increased amount of photic phenomena produced by a refractive lens in the dominant eye. Otherwise, if the patient is reasonably happy with the first eye, we go for mix-and-match with a refractive ReZoom (Advanced Medical Optics),” Dr. Piovella explained.

Another key point for success is giving support to the patient in the process of adapting to the new way of seeing after implantation.

“We use Eyevispod computerized software, which simulates night vision problems. A series of images are shown to the patient before implantation and during the first 3 months of the follow up. By comparing his or her vision with what is shown in the simulation, the patient becomes aware of the progressive improvements and decreased photic phenomena that occur with time and adaptation,” Dr. Piovella said.

He maintained that what patients report in the postoperative period are mostly observations about their new visual function and are not necessarily complaints. They need to be reassured that what they are experiencing is normal, he said.

By using this strategy, he has been able to use the mix-and-match procedure successfully in about 40% of his patients. Patients who received bilateral Tecnis also showed a high degree of satisfaction, he said.

“If refractive errors of more than 0.50 D persist, it is worth planning enhancement, and patients, particularly astigmatic patients, should be aware from the start that this might be necessary,” Dr. Piovella said.

Bilateral vs. mix-and-match

Frank Goes, MD, of Antwerp, Belgium, said he uses bilateral Tecnis or a Tecnis-ReZoom (AMO) combination. In a study, he compared the results of 108 eyes of 54 patients implanted bilaterally with the Tecnis IOL and 56 eyes of 28 patients implanted with the mix-and-match technique. All of them were clear lens exchange patients. Vision at distance, intermediate and near as well as reading speed were analyzed at 3 months. Secondary effects and patient satisfaction were also evaluated.

Magda Rau

UCVA showed an improvement in all patients, increasing from 20/80 to 20/24 in the first group and from 20/85 to 20/22 in the second group. Monocularly, 132 of 136 of the Tecnis eyes and 15 of 28 of the ReZoom eyes could read J1.

“Near acuity is definitely one of the strong points of the Tecnis lens,” Dr. Goes noted.

“All but four of the patients in the Tecnis group and all 28 patients of the Tecnis-ReZoom group were spectacle free,” he said.

Multifocal IOLs are also the first choice of Magda Rau, MD, who presented the results of 240 eyes of 120 patients implanted with either bilateral or mixed multifocal IOLs in the Day Clinic Cham, Germany, between August 2006 and June 2007.

Patients were equally distributed in three groups: mix-and-match with ReZoom-Tecnis, bilateral Tecnis or bilateral ReZoom.

UCVA for distance, intermediate and near, reading speed using Radner charts and contrast sensitivity were examined. Special attention was given to the quality of vision, the need to wear glasses and the personal satisfaction of the patient.

“Mean UCVA was excellent, and absolutely comparable in the three groups at all distances, with only small, non-statistically significant differences,” Dr. Rau said.

The mix-and-match group achieved the highest patient satisfaction, with 92% of patients saying they were happy with the outcomes of the procedure, vs. 83% of the ReZoom group and 87% of the Tecnis group.

“In my opinion, the mix-and-match approach is appropriate for selected patients and gives them better all-round vision,” she said.

Aspheric ReSTOR

Preliminary results with the Alcon AcrySof ReSTOR SN6AD3 were presented by Thomas Kohnen, MD, on behalf of Rudy Nuijts, MD. This model differs from the standard ReSTOR in the new aspheric surface design, aimed at improving image quality by elimination of the spherical aberration that is typical of spheric lenses.

Thomas Kohnen

As Dr. Nuijts said, “Aspheric optics align the light rays to compensate for positive corneal spherical aberration, resulting in enhanced image quality.”

Dr. Nuijts implanted 30 eyes of 15 patients with this lens and has been following them prospectively for 8 to 14 weeks. At 3 months, aberrations, spectacle dependence, vision-related functioning, patient satisfaction and visual disturbances were evaluated. Results were compared with those of the standard ReSTOR lens.

“The new lens shows excellent visual acuity outcomes both for far and near vision, and all parameters were slightly better compared with the classic ReSTOR,” Dr. Kohnen said. In particular, a clinically significant difference in monocular mesopic contrast sensitivity was found between the two lenses.

Bifocal IOL

The more recent model of the bifocal Acri.Lisa, the 356 D, was implanted in 15 eyes of 10 patients at the University Eye Clinic of Verona, Italy. The follow-up has now reached 3 months.

LISA is an acronym for light intensity distribution (L) independent from pupil size (I), smooth refractive/diffractive surface profile (S) and optimized aspheric optic (A). This design is specially intended to reduce disturbing light phenomena, including scattered light and halos. With the Acri.Lisa, aberration correction is distributed over the whole eye.

“Results were very satisfactory for far and near vision, but intermediate vision is still suboptimal,” Emilio Pedrotti, MD, said. Contrast sensitivity with and without glare was within normal ranges, comparable to standard monofocal pseudophakic eyes.

Hydrophobic aspherical one-piece

AMO’s new hydrophobic aspherical one-piece Tecnis performs well clinically, according to Dr. Auffarth. The design is aimed at providing easier handling and implantation, in combination with the proven benefits of the classical Tecnis in terms of reduction of spherical aberration. By targeting zero spherical aberration, Tecnis aspherical lenses improve visual quality.

Unlike first-generation one-piece lenses, the Tecnis 1 has no interruption in the optic-haptics junction and a 360º square-edge design that minimizes cell migration.

At the University Eye Clinic of Heidelberg, this lens first underwent a laboratory study with insertion in an artificial eye. In the next stage, the lens was implanted in 25 patients between the ages of 55 and 73 years. Results were compared with the Tecnis ZA90003 and the AcrySof IQ, particularly in terms of aberrations and visual quality.

“The new Tecnis 1 shows similar results to the other two lenses in reducing spherical aberration and provides optimal visual outcomes and visual clarity,” Dr. Auffarth said.

Accommodation restored

The WIOL-CF, manufactured by GEL-MED International, is an accommodative lens designed to restore accommodation ability. This IOL obtained a CE Mark in 2004 and is currently marketed in several European countries.

“It is a large 8-mm lens, which can be implanted through a small incision,” Jiri Pasta, MD, of Praha University Hospital, Czech Republic, said.

Best results are obtained in younger, active patients between the ages of 50 and 59 years, where ample movement of the lens has been observed by ultrasound biomicroscopy.

“These patients rarely need spectacles. Only 25% of them use them occasionally for reading J1 or J2. Middle distance vision is also very good, with 80% of the patients using the computer without glasses,” Dr. Pasta said.

When to mix-and-match

John Chang, MD, said that since the end of 2003 he has implanted 500 eyes with multifocal IOLs. Half of those were Tecnis multifocal IOLs, the others were more or less equally distributed between the Array (AMO), ReZoom and ReSTOR (Alcon). Only two eyes necessitated explantation: One was a post-LASIK myopic eye with cataract and the other one developed diabetic maculopathy.

“As we know, all these lenses are very good, but they have limitations,” Dr. Chang said. “With bilateral diffractive lenses patients have good distance and near but poor intermediate vision. With bilateral refractive lenses, patients have fairly weak near vision. By implanting a diffractive lens in one eye and a refractive lens in the other eye, the best of both worlds can be achieved,” Dr. Chang said.

His strategy with multifocal lenses is a two-step procedure that takes as a starting point the predominant activities of patients’ day to day life.

“In patients who read a lot I implant a diffractive lens in the non-dominant eye. If they are happy with their near vision, I offer a refractive IOL in the dominant eye to give better distance and some intermediate vision for computer work. If they are not satisfied with their near vision, I implant a diffractive also in the dominant eye,” he said.

On the other hand, in patients who predominantly drive, use the computer and who do not read very much, he implants a refractive lens in the dominant eye. If they complain of poor near vision, he offers a diffractive IOL in the other eye.

So far, he has used the mix-and-match approach in 27 patients. They all tolerated the different lenses very well, had only minor complaints of night vision disturbances and a fairly high degree of satisfaction, he noted.

None of the patients wear spectacles for distance vision, 95% read and use the computer without spectacles, and the remaining 5% use them occasionally.

Future designs

A pseudo-accommodative IOL that creates bifocality through air and liquid, produced as a prototype in the laboratory of the Gandhi Eye Hospital of Aligarh, India, was presented by Meenakshi and Yogesh Gupta, MDs.

“The IOL consists of a hollow spherecoaxial plano-convex lens combination. The anterior lens has a convex surface with a refractive power of 20 D within the eye, and the posterior lens, also with a convex anterior surface, has a power of about 3 D in air. The little space in between these two lenses is sealed around the periphery and filled to about two-thirds with liquid and one-third with air,” Dr. Gupta said.

When the eyes are directed horizontally for distance vision, the liquid occupies the space in between the optical zones of the lenses, and neutralizes the 3 D power of the posterior lens. When the eyes swivel down 30º to 40º for near vision, the fluid level remains horizontal and the air occupies the space in between the optical zones of the lenses, leading to restoration of the 3 D additional power of the posterior lens. The resulting total power of the lens for near is 23 D.

So far, the lens has only been tried in model eyes and enucleated animal eyes.

“This lens is designed to provide power changes for vision at distance and near. This new concept holds tremendous promise and may prove to be a breakthrough in bifocal IOL technology,” Dr. Gupta said.

A note from the editors:

To facilitate bringing news to readers rapidly, for OSN SuperSite articles and meeting wrap-up articles, OSN departs from its editorial policy and typically does not send these items out for source corrections.

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• Michela Cimberle is an OSN Correspondent based in Treviso, Italy, who covers all aspects of ophthalmology. She focuses geographically on Europe.