Panel outlines new IOL technologies

Robert H. Osher, MD, moderated a panel at AAO on emerging IOL technologies.

NEW ORLEANS — A panel of leading cataract surgeons discussed a number of innovative IOLs currently in development during a symposium called “Cataract Surgery: Living on the Edge” during the American Academy of Ophthalmology meeting.

The rapid-fire session, organized and led by Robert H. Osher, MD, included investigators’ impressions of ultrathin lenses, adjustable IOLs and other technologies on the horizon.

Dr. Osher noted that the ThinOptx Ultra Choice IOL has by now been implanted in “thousands of eyes worldwide.”

The ThinOptx lens is less than 0.5 mm thick at its thickest point and can be rolled to fit through an incision of less than 2 mm. One face of the 5.5-mm optic is divided into concentric zones, stepped in height, with a different curvature on each step so that all light traveling through the lens is focused at the same point on the retina.

The lens is in early stages of U.S. clinical trials, Dr. Osher said, and the company is seeking funding.

An entirely diffractive phakic IOL, the VisionMembrane lens, is now in clinical trials in Mexico, Dr. Osher said. This silicone lens with a 6-mm optic is less than 1 mm thick, he said.

Richard L. Lindstrom, MD, said diffractive optics may be "the way to go" for phakic IOLs.

Richard L. Lindstrom, MD, one of the panel members at the session, said diffractive optics “may be the way to go” for phakic IOLs. He said with the limited space for a lens in the anterior chamber, the thin profile that can be achieved with diffractive optics may be an advantage over conventional refractive optics.

The Light Adjustable Lens (LAL) from Calhoun Vision has now begun clinical trials outside the United States, Dr. Osher said. The spherical and astigmatic power of this lens can be adjusted after implantation with a special laser made by Zeiss.

Dr. Osher said that about 30 of these lenses have been implanted to date. Twenty patients have undergone spherical adjustment of the lens, he said, and 70% of those achieved a plano refraction. There have also been toric adjustments in two patients with good results, he said.

The LALs implanted to date have been made of silicone. Samuel Masket, MD, another panel member, said it is hoped the light-adjustable concept can be carried over to acrylic materials.

I. Howard Fine, MD, also on the panel, said the full promise of the technology will be serial adjustment. If the lens can be adjusted over the course of the patient’s life, it can be changed to refine its accuracy or to adapt to different visual needs at different times, he said.

Dr. Osher suggested that the adjustable lens technology may be especially important for refractive lens exchange.

“If we’re going to be tackling young patients who see well and who have to pay a lot of money for a refractive surgical procedure, a 0.5-D error can be significant,” he said.

Dr. Masket spoke about the SmartLens, in development by Medennium. This lens, made from a hydrophilic acrylic material, is inserted into the eye in the shape of a 1-mm-diameter rod, and it expands to fill the capsular bag. Dr. Masket said the lens has been implanted in cadaver eyes through a 2-mm incision and is currently undergoing toxicology and other preclinical studies.

Panel members speculated that the ReStor lens, a diffractive-refractive pseudoaccommodative IOL from Alcon, will be available in the “very near future.” (An Alcon official said in an interview that U.S. regulatory approval of the ReStor is anticipated in the first quarter of 2005.)

Dr. Lindstrom noted that Alcon had acquired the diffractive multifocal IOL concept used by 3M in the 1980s and “clearly made it significantly better.” He and Dr. Osher, who were both investigators of the 3M lens, said they thought the ReStor shows promise and has performed well in clinical trials to date.

Another Alcon IOL, the Toric AcrySof, is “right behind ReStor in the regulatory process,” according to Stephen S. Lane, MD, another panelist. He said the fact that the Toric and the ReStor are both built on Alcon’s AcrySof design raises the possibility that the two elements can be combined in the future.

The panelists also discussed two IOLs currently available, the Alcon AcrySof HOA and the Bausch & Lomb SofPort AO. The Alcon lens was released earlier this year, and B&L lens was launched here at the AAO meeting.

Both the new lenses have aspheric surfaces on one or both sides, and both seem to have been inspired by the success of the Tecnis IOL from Advanced Medical Optics, the panel members said. The Tecnis was designed with a modified prolate anterior surface to correct for negative asphericity in the human cornea.

The AcrySof HOA has its aspheric surface on the back of the IOL, avoiding the need to make the edge of the lens thicker. The SofPort AO has aspheric optics on both its front and back surfaces so that it induces no spherical aberration.

“The idea that aspheric lenses provide superior vision is not a surprise, based on experience with the Tecnis,” Dr. Masket said.

Dr. Lindstrom said the SofPort AO lens “will be robust to decentration and tilt.”