December 2008

 

CATARACT/ IOL

 

IOL options continue to expand


by Rich Daly EyeWorld Contributing Editor

 

Silicone IOLs

Acrylic IOLs

 

New lenses present new refractive opportunities, as well as creating new surgical challenges

Intraocular lenses have seen important improvements in recent years, and some of the biggest advances have come from lenses that attempt to address astigmatism and correct presbyopia.

Among presbyopia-correcting IOLs, two lenses have received Food and Drug Administration (FDA) approval for modifications within the past year: the ReSTOR aspheric and the CrystaLens HD-100. The ReSTOR Aspheric (Alcon, Fort Worth, Texas), launched in late 2007 as the most recently approved posterior chamber IOL, has completely replaced the spherical ReSTOR for most practices, said David F. Chang, M.D., clinical professor, University of California, San Francisco. He also has found the CrystaLens HD-100 (Bausch & Lomb, Rochester, N.Y.) is an improved option for achieving uncorrected near vision performance. “However, it is not yet clear to me whether there is some slight sacrifice in distant vision with smaller pupils, because there is additional [plus] power incorporated into the central zone,” Dr. Chang said. “This creates a tendency to over minus Crystalens HD patients when refracting them.”

Lisa Arbisser, M.D., adjunct clinical associate professor, John A. Moran Eye Center, University of Utah, Salt Lake City, said that she has switched nearly all of her presbyopia patients from the standard CrystaLens to CrystaLens HD-100 IOLs. The main problem she has found to persist with the new CrystaLens is that a small percent of patients continue to have unpredictable capsule contraction that leads to some progressive myopia in the early post-op period. Another problem Dr. Arbisser has found is that the effective lens position is slightly less predictable than with standard lenses.

Her response to these problems has been to expand the period between lens implantations of each patient’s eyes from one to two weeks apart. This approach allows an unexpectedly myopic eye to be balanced by targeting the other eye for distance.

Among the advantages of the CrystaLens is its use of a new inserter, which is a single-push device that does not require twisting or turning, said Rosa Braga-Mele, M.D., M.Ed., associate professor, University of Toronto, Toronto, and director, cataract unit and surgical teaching, Mt. Sinai Hospital, Toronto. She also uses a STAAR Surgical, (Monrovia, Calif.) inserter, which allows her to get the lens through a 2.65 mm incision.

Dr. Arbisser’s experience with the ReSTOR Aspheric has led her to conclude that its usefulness is more limited. The lens’ refractive capabilities and limitations make it narrowly suited for patients who mainly want to pass a drivers test and see fine print up close but otherwise have a perfect visual system. She would not use the lens if she was concerned about the impact of reduced light on the patient or if they were likely to develop other visual system anomalies that the ReSTOR would be unable to address.

Among the newest IOLs Dr Braga-Mele has begun using is the Akreos Advanced Optics Aspheric Lens (model AO60, Bausch & Lomb), a four-haptic, single-piece IOL with an aspheric optic. The design is uniform from center to edge so that any shifting or tilting will not induce spherical aberrations. Another advantage of the lens, she found, is its 360-degree square edge, which keeps the posterior capsular opacification (PCO) rate “relatively low” among her patients.

“Patients do not complain of dysphotopsias at all with this IOL and there are no glistenings or markings at all on the IOL,” Dr. Braga-Mele said.

Another aspheric option that has been approved in Canada is the micro-incision lens (MIL Akreos, Bausch & Lomb). This lens is based on the same platform as the Akreos AO IOL except that it has been “thinned out” and includes a 360-degree posterior square edge vaulted 10 degrees posteriorly. A major advantage of this lens, Dr. Braga-Mele said, is that it is able to be injected though a 1.8 mm incision. “So if you are doing micro-incision cataract surgery [MICS] you don’t have to enlarge the incision size,” Dr. Braga-Mele said.

Lenses battle astigmatism

When confronted with a patient who needs significant astigmatism correction, Dr. Chang frequently uses the AcrySof Toric (Alcon) IOL. His research on the lens—accepted for future publication in the Journal of Cataract and Refractive Surgery—found excellent rotational stability that was even better than he found in an earlier personal series of his STAAR toric IOLs recipients.

“Besides eyes with high degrees of corneal cylinder, I am using toric IOLs instead of limbal relaxing incisions [LRIs] for lower amounts of astigmatism (e.g. 1.0 – 1.5 D) in certain situations,” he said. “These would include younger patients, corneas with an oblique astigmatic axis, and eyes without a classic bow tie topographic pattern.”

The Centers for Medicare and Medicaid Services (CMS) ruled in 2007 that cataract patients could choose the AcrySof Toric as an upgraded alternative to standard lenses.

Thomas A. Oetting, M.D., professor of clinical ophthalmology, and director, Ophthalmology Residency Program, University of Iowa, Iowa City, Iowa, said he also has used this lens when post-op induced astigmatism is a major concern. “I have had good luck with this device,” he said.

Like Dr. Chang, Dr. Arbisser also has moved away from the STAAR toric. Her decision was based on her concerns that the plate haptics used by the IOL are not “an appropriate design, at all, let alone for toricity.”

Dr. Arbisser has favored the AcrySof Toric one piece acrylic IOL for any patients with enough astigmatism to require it, as well as for patients who prefer to see well without glasses. She has limited her use of astigmatic keratotomy since the AcrySof Toric became available, except for people who have small amounts (one diopter or less) of astigmatism. Regardless of the toric lens chosen, the largest challenge surgeons face is how to ensure that the pre-op measurements for these lenses are “exactly right,” Dr. Arbisser said.

The use of manual K readings continues to present consistency and logistical challenges. “The only times I have not had perfect outcomes I’ve suspected that the pre-op manual K readings weren’t perfect,” she said. “It is a pretty subjective measurement, however where you put it is where it is staying, guaranteed.”

The Tecnis one-piece IOL (Advanced Medical Optics, Santa Ana, Calif.), based on the same technology as the Tecnis three-piece IOL and including a regular haptic configuration, has become another recent option for Dr. Braga-Mele. She favors the lens, which was launched in April, because it has thin and soft haptics, centers well and also uses a 360-degree square edge design. One drawback she has found that is that the Tecnis standard inserter is “a bit finicky” due to the twisting and turning necessitated by its design.

Multifocals: best yet to come? Coming changes should expand the use of multifocal IOLs. In the coming year, according to Dr. Chang, two new multifocal designs already available to European patients will seek U.S. regulatory approval. One lens under consideration is the Tecnis multifocal diffractive IOL (AMO). The second lens moving toward a FDA decision is a low-power ReSTOR. Dr. Chang said approval of the new ReSTOR would create the possibility of combining it with the higher power ReSTOR in the opposite eye to provide better intermediate vision. Also moving toward a decision by U.S. regulators is the model 311 (Ophthtec USA, Boca Raton, Fla.) iris reconstruction IOL. This lens, now in phase III FDA trials, has provided good results for patients missing an iris, according to Dr. Oetting.

Accommodation improvements targeted

Among the coming IOLs that hold some of the greatest promises for future advances in refractive surgery are accommodating lenses under development. The Synchrony (Visiogen, Irvine, Calif.) dual optic accommodating IOL is nearing completion of one year data collection on 300 patients in a Phase II/III clinical trial, said Dr. Chang, who is the lens’ U.S. medical monitor.

Another lens that has generated significant discussion in recent years, the Light Adjustable Lens (LAL, Calhoun Vision, Pasadena, Calif.), is about to commence U.S. clinical trials. “All surgeons hope that the next generation of refractive IOLs will provide even better options for our patients,” Dr. Chang said.

Editors’ note: Dr. Chang has financial interests with Advanced Medical Optics (AMO, Santa Ana, Calif.), Alcon (Fort Worth, Texas), Calhoun Vision (Pasadena, Calif.), and Visiogen (Irvine, Calif.). He donates his fees from AMO and Alcon to the Himalayan Cataract Project. Dr. Braga-Mele has financial interests with Alcon, Bausch & Lomb (Rochester, N.Y.), and STAAR (Monrovia, Calif.). Dr. Arbisser has financial interests with Alcon. Dr. Oetting has no financial interests related to his comments.

Contact information:

Arbisser: 563-323-2020, drlisa@arbisser.com
Braga-Mele: 416-462-0393, rbragamele@rogers.com
Chang: 650-948-9123, dceye@earthlink.net
Oetting: thomas-oetting@uiowa.edu

IOL options continue to expand IOL options continue to expand
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