February 2015

 

REFRACTIVE

 

New technology IOLs: where innovation lies


by Michelle Dalton EyeWorld Contributing Writer

 
 

The holy grail is being able to provide clear vision in both eyes; to get an implant that truly does accommodate; and to have an implant that gives a wide enough range of focus. Nick Mamalis, MD

 

Experts discuss innovations in IOLs

Discussing new technology involves more than just the next iteration of a technology or a minor (but still useful) enhancement. Last month, EyeWorld asked experts around the world for their opinions on extended depth and range of focus lenses. This month, EyeWorld asked about corneal inlays, accommodating, and true new technologies currently under investigation in at least one region of the world. Here is what the experts said.

Where the interest lies

One of the biggest challenges for cataract surgeons today is that most lenses will improve best corrected visual acuity (BCVA), but we still havent nailed the refraction. We still have issues with IOL predictions and accuracy, and there are still some patients who will develop posterior capsule opacification [PCO] after surgery, said Arthur B. Cummings, MB ChB, FCS(SA), MMed(Ophth), FRCS(Edin), consultant ophthalmologist at the Wellington Eye Clinic and Beacon Hospital, Dublin.

The Harmoni lens (ClarVista, Aliso Viejo, Calif.) not only boasts the lowest PCO rate of any currently available lens (80% less PCO in rabbit studies), but it will allow surgeons to swap out the optic in the case of a refractive surprise while the haptics remains in place in the capsular bag. This lens has an amazingly stable base because of the haptic configuration and a capsular tension ring built around the lens, Dr. Cummings said. With a completely interchangeable optic, he thinks that the lens will also have great potential in pediatric cases in addition to the traditional premium lens patient. Jorge L. Alio, MD, PhD, professor and chairman of ophthalmology, Miguel Hernandez University, Alicante, Spain, and medical director of Vissum Corporation, Spain, has discussed the 16-month results in 52 cases implanted with the Lumina IOL (AkkoLens, Breda, the Netherlands) in Bulgaria, said Liliana Werner, MD, PhD, associate professor, and co-director of the Intermountain Ocular Research Center, John A. Moran Eye Center, Salt Lake City. The range of accommodation obtained was 2 D to 5 D, and the hydrophilic acrylic lens has shifting cubic optical elements designed to be implanted in the sulcus. The focal length is supposed to change when the refractive elements shift laterally. Long-term clinical results will tell if constant shifting of the optic elements will result in problems such as pigmentary dispersion, she said.

Outcome variability is an issue in pseudophakic accommodation, but at this moment, we have a lens that really works, Dr. Alio said. As it is a sulcus lens, safety issues still have to be solved during this year. As the Light Adjustable Lens (LAL, Calhoun Vision, Pasadena, Calif.) becomes available in certain markets, research is being performed on other IOLs that can be adjusted noninvasively in the postoperative period such as liquid crystal IOLs with wireless control and IOLs that can be adjusted by using the femtosecond laser or 2-photon chemistry, Dr. Werner said. (See this months Device focus for an in-depth look at the LAL.) These other lenses are all in early stages of development. Multicomponent IOLs that can be adjusted by surgical exchange of the optic component only, while the base component remains in place, are also under clinical evaluation, from developers Infinite Vision Optics (IVO, Strasbourg, France) and ClarVista Medical, she said.

True accommodation?

The group of Dr. Werner and Nick Mamalis, MD, has evaluated the FluidVision accommodating IOL (PowerVision, Belmont, Calif.) in different rabbit studies and observed that overall capsular bag opacification with this lens was remarkably low in comparison to a commercially available control. The lens incorporates large, hollow haptic elements that keep the anterior and posterior capsules apart. The optic and haptics are made of a hydrophobic acrylic material, and the haptics and interior of the optic are filled with silicone oil that is index-matched to the acrylic, she said. The lens is designed so that when the haptics are subjected to accommodative forces, silicone oil is pushed into the optic through fluid channels that connect the haptics to the optic. As silicone oil flows into the optic, the deformable front optic surface is changed, increasing the power of the lens, she said. The lens is under evaluation in Europe.

The lens may enter U.S. trials as early as the first half of this year, said Mark Packer, MD, CPI, medical director of Boulder Eyes, Boulder, Colorado. Some of the data coming out of the European multicenter studies indicates the lens changes shape, and the company can correlate the shape change to an amount of accommodation by measuring the surface curvature of the fluid-filled bag, he said. In some studies, the accommodation has been as high as 5 D, he added. Dr. Mamalis, professor of ophthalmology, co-director of the Intermountain Ocular Research Center, and director of ocular pathology, John Moran Eye Center, added that as this lens moves the silicone from the haptics into the optic, it changes the curvature on the optic, and you get quite a large accommodating amplitude. Dr. Alio said trifocal IOLs in development with extended depth of focus work on achromatization and adjustment of the IOL asphericity. Piggyback multifocal IOLs are currently under study, both diffractive and refractive varifocal. We also have toric sulcus lenses for piggybacking. With all these lenses, we have an unlimited capability to indicate a multifocal lens, even in patients with a previous monofocal lens operated some time ago. The diffractive IOL is from Carl Zeiss Meditec (Jena, Germany) (refractive varifocal) and the refractive IOLs are the Mplus (Oculentis, Berlin) and the Rayner Sulcoflex (East Sussex, U.K.) (refractive multifocal).

Dr. Mamalis acknowledged the strides that developers have made in trying to provide true accommodation. [But] any lens that splits the image has the potential for the bothersome side effects associated with the multifocal lenses, he said. A lot of people adapt quite well to them and do just fine. Some people dont. Those are the people who we have to consider doing a lens exchange. In Europe, several trifocal lenses are doing pretty well, Dr. Cummings said, adding anecdotal evidence that these lenses are helping to grow a once-stagnant market. Leading trifocal IOLs include the AT.LISA (Carl Zeiss Meditec) and the FineVision (PhysIOL, Liege, Belgium). Theyre almost like regular monofocals with an absolute defocus curve, good distance, a minimal gap for intermediate, and good near, he said. The 3 troughs run into each other; people dont complain about the rings nearly as much as they do from regular multifocals. What excites Dr. Mamalis about the future of these lenses is that were coming up with totally new ways of providing true accommodationa lens that truly changes shape and focus much like our crystalline lens does.

The holy grail is being able to provide clear vision in both eyes; to get an implant that truly does accommodate; and to have an implant that gives a wide enough range of focus so people can read, work on a computer, and see distance objects clearly, Dr. Mamalis said.

Claudio Trindade, MD, is developing a novel small aperture implant made of black acrylic and implanted in the sulcus that acts as an intraocular pinhole, improving vision in cases of irregular corneal astigmatism and extending depth of focus of normal pseudophakic eyes. It has generated significant improvement in visual function, no signs of complications, with high patient satisfaction in all cases, Dr. Werner said, but the study was performed in only 6 patients3 pseudophakes and 3 patients who had previously complained about poor near vision after cataract surgery. The Synchrony lens (Abbott Medical Optics, AMO, Abbott Park, Ill.) does actually accommodate. The dual optic system comes apart and goes together, and gives you near and distance vision, Dr. Mamalis said. I have patients with the Synchrony IOL approaching 5 years of follow-up exams from the original U.S. study with persistent clear distance and near vision, he said.

Dr. Alio disagreed, noting our studies show the Synchrony does not accommodate after 3 months of follow-up, and the lens was withdrawn from the market in 2014 for reasons related to its efficacy. In Europe, the next-generation Synchrony Vu accommodating IOL features a central blended aspheric zone designed to extend the depth of focus.

Purely increased depth of focus lenses are under investigation, but the problems with centration and quality of vision are still to be solved, Dr. Alio said. Secondary multifocal IOL implantation and toric intraocular lenses are indeed a tremendous opportunity for patients now in Europe. Toricity assisted by the new technologies to allocate the lens in the precise meridian is improving the refractive outcomes of cataract surgery.

Down the road

The Sulcoflex Pseudophakic Supplementary IOL (Rayner) is implanted in the ciliary sulcus to correct any residual postoperative refractive errors following the implantation of a conventional IOL in the capsular bag, which is great for someone who had surgery 10 years ago and wants to enhance their vision, Dr. Mamalis said. The lens is not available in the U.S.

Dr. Alio is really looking forward to having a customized Q value for lenses as occurs in the MyLentis (Oculentis) study, where surgeons manipulate the asphericity in normal and post-laser vision correction surgery. Negative dysphotopsia lenses (like the lens designed by Samuel Masket, MD) are under evaluation in Europe. These lenses probably will solve negative dysphotopsia, Dr. Alio said. Negative dysphotopsia is not common, but it is appreciated by some doctors as an opportunity to eliminate this potential optical complication. Positive dysphotopsia is caused by high index of refraction lenses and is impossible to avoid, but piggybacking them with a neutral lens, including some minor refractive residual error, solves the problem.

Editors note: Dr. Alio has financial interests with AkkoLens and Carl Zeiss Meditec. Dr. Cummings has financial interests with Alcon (Fort Worth, Texas). Dr. Packer has financial interests with AMO, Calhoun Vision, Carl Zeiss Meditec, PowerVision, and Rayner Intraocular Lenses. Dr. Werner has financial interests with AMO, AcuFocus, Alcon, Calhoun Vision, ClarVista, PhysIOL, PowerVision, and Rayner Intraocular Lenses. Dr. Mamalis has no financial interests related to this article.

Contact information

Alio: jlalio@vissum.com
Cummings: abc@wellingtoneyeclinic.com
Mamalis: nick.mamalis@hsc.utah.edu
Packer: mark@markpackerconsulting.com
Werner: liliana.werner@hsc.utah.edu

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