Novel IOL design concepts raise bar

Ongoing advances in IOL design, materials and optics continue to enhance cataract surgeons’ ability to maximize postoperative visual and refractive outcomes.

Evolving monofocal, multifocal, toric and accommodating IOL technologies promise to help surgeons improve basic visual function, treat presbyopia and correct refractive astigmatism.

Basic improvements to monofocal and premium refractive lenses include acrylic materials that help prevent visual disturbance, Mark Packer, MD, said.

“A defect-free or glistening-free material is important,” he said. “I also believe in using material that has the least amount of inherent aberrations in it.”

Other recent developments include a 360° posterior square-edge design that helps prevent posterior capsule opacification. In addition, single-piece acrylic aspheric designs allow incisions of 2.2 mm to 2.5 mm, Dr. Packer said.

Jay S. Pepose

Jay S. Pepose, MD, said toric versions of the AcrySof IQ ReSTOR (Alcon) and Crystalens (Bausch + Lomb) will be valuable additions to the cataract surgeon’s arsenal. The AcrySof IQ ReSTOR toric IOL is available in Europe but is not yet approved by the U.S. Food and Drug Administration.

Multifocal and accommodating IOLs

Dr. Packer said he prefers the Tecnis multifocal IOL (Abbott Medical Optics) and Crystalens, which is the only accommodating IOL approved by the FDA.

He said he uses the AcrySof IQ ReSTOR multifocal IOL instead of the Tecnis only in selected cases.

Dr. Packer said he favors the Crystalens for patients who have undergone RK and for those concerned about postoperative halos.

The Crystalens may provide postoperative visual acuity approaching 20/20 and reading vision of J1, especially in eyes with long axial length and high myopia, Dr. Packer said.

The Synchrony dual-optic accommodating IOL (AMO) provides 2 D to 3 D of effective accommodation, Dr. Packer said.

“That lens is a big winner. It’s close to getting approval,” he said. “At least all the studies have been done and all the data is with the FDA. I’m looking forward to being able to use it.”

Dr. Pepose said the Crystalens is his go-to accommodating IOL for most patients. The Tecnis multifocal is a suitable backup in certain cases.

“Generally, my first choice is bilateral Crystalens and my second choice might be mixing and matching Crystalens and Tecnis multifocal,” he said.

Dr. Pepose said he targets distance vision in the dominant eye and offsets the nondominant eye with near power for bilateral Crystalens cases.

“It varies, based on the patients,” Dr. Pepose said. “If their main concern is good distance and intermediate and they don’t mind occasionally wearing reading glasses, I might do a –0.5 D offset on the second eye. But for smaller print or bad lighting, you might need to wear reading glasses.”

However, implantation of a Tecnis multifocal IOL in the nondominant eye may be appropriate if any offset with another Crystalens is intolerable or unacceptable to the patient, Dr. Pepose said.

Dr. Pepose said he also prefers the Crystalens over a multifocal for post-refractive patients undergoing cataract surgery. He noted the importance of avoiding the need to perform lens exchange.

“I feel like they already have a multifocal cornea and they have enough aberrations,” he said. “I’m not sure if the IOL and the center of the ablation will be misaligned and result in increased aberrations, perhaps requiring IOL explantation. I just don’t like explantation being the fail-safe. Explanting a lens has risks.”

Ambitious new concepts

Three accommodating IOL designs are in development. The NuLens comprises a piston activated by the ciliary muscles that pushes silicone gel through a small hole, forming a bulge that alters the shape of the IOL and changes lens power.

Dr. Pepose described the NuLens as revolutionary because its optical mechanics are based on those of aquatic birds.

“Diving fowl have to look at something from the air and still keep it in focus when the dive into the water, so they’re pushing their gel-like lens through a muscular iris diaphragm, basically, producing high degrees of accommodation,” Dr. Pepose said.

The FluidVision accommodating IOL (PowerVision) is an acrylic lens containing a viscous silicone fluid. Accommodative movement results from ciliary muscle forces transmitted through the zonules to the capsular bag.

The Elenza Electro-active AutoFocal IOL has a micro-battery and a switchable optical element that automatically adjusts focus electronically for various distances. The technology is similar in some aspects to that utilized by PixelOptics, which also developed electronic focusing spectacles, Dr. Pepose said.

“Their motto is that they’re getting accommodation without movement,” he said. – by Matt Hasson

Reference:

• Alio JL, Ben-nun J, Rodriguez-Prats JL, Plaza AB. Visual and accommodative outcomes 1 year after implantation of an accommodating intraocular lens based on a new concept. J Cataract Refract Surg. 2009;35(10):1671-1678.

• Mark Packer, MD, can be reached at Drs. Fine, Hoffman & Packer, LLC, 1550 Oak St., Suite 5, Eugene, OR 97401; 541-687-2110; fax: 541-484-3883; email: mpacker@finemd.com.
• Jay S. Pepose, MD, PhD, can be reached at Pepose Vision Institute, 1815 Clarkson Rd., Chesterfield, MO 63017; 636-728-0111; email: jpepose@peposevision.com; website: www.peposevision.com.
• Disclosures: Dr. Packer is a consultant for Abbott Medical Optics, Advanced Vision Science, Bausch + Lomb Surgical, Corinthian Ophthalmic, GE Healthcare, Ista Pharmaceuticals, LensAR, mTuitive, Rayner Intraocular Lenses, Surgiview LLC, Transcend Medical, TrueVision Systems and WaveTec Vision Systems. Dr. Pepose is a consultant for Abbott Medical Optics, Acufocus, Bausch + Lomb and Elenza. He is medical monitor of clinical trials for the Crystalens toric IOL.