MONOFOCAL ASPHERIC IOLS

Accelerating the Use of Aspheric IOLs

Find out what these cutting-edge lenses can do for your patients — and you.

► As a cataract surgeon stepping out of training and into practice, your employer expects you to roll up your sleeves and jump right in, meeting patients' expectations with excellent surgeries and contributing to the growth of the business.

"The young surgeon has something to prove," says Robert J. Noecker, M.D., M.B.A., UPMC Eye Center, Pittsburgh. "People are watching your results early on. If your patients see well, the optometrists and others who've sent them to you will send you more patients. If your patients have complaints about visual outcomes, that won't happen."

Light rays refracted from different parts of spherical surfaces, such as lenses, are focused to different places, creating spherical aberration. In the eye, spherical aberration blurs the resultant image and can cause glare, halo and a reduction in contrast sensitivity.

Making use of monofocal aspheric IOLs is one way to help ensure you begin your quest for success on the right foot. These IOLs enable you to provide patients with improved visual outcomes compared to standard spherical monofocal IOLs, without any change in your current phaco/implant technique. Their optical performance is based on the fact that the human visual system functions best when the positive spherical aberration of the cornea is balanced by the negative spherical aberration of the crystalline lens.

All standard monofocal IOLs are positive spherical aberration lenses. Therefore, replacing the crystalline lens with a standard monofocal IOL leaves the eye with too much positive spherical aberration, which causes blur, a reduction in contrast sensitivity and relatively poorer functional vision. Aspheric IOLs do not add positive spherical aberration to the eye. Therefore, they induce far fewer unwanted optical side effects and provide better quality vision than any of their spherical predecessors.¹

Depending on design, aspheric IOLs introduce either negative spherical aberration or no spherical aberration at all. The result, Dr. Noecker explains, is "Patients see better and have fewer complaints."

Taking the Pressure Off

Just a few years ago, it wasn't uncommon for cataract patients to undergo successful surgery with implantation of a spherical IOL, have 20/20 post-op Snellen acuity, but still perceive problems with their vision. They'd return to the office asking why they couldn't see well at night, walk confidently down a dimly lit stairway or why their vision just didn't seem quite right. Surgeons had no real explanation to offer, and this created a difficult situation for the treating physicians, especially those new to practice.

"It was difficult for a relatively inexperienced surgeon to face a list of complaints after producing what appeared to be a perfect outcome," says Mark Packer, M.D., Drs. Fine, Hoffman & Packer, Eugene, Ore. "You couldn't dismiss what the patient was experiencing, yet you really couldn't explain it either."

Head for the Cutting Edge

Aspheric IOLs give you the opportunity to avoid this pressure situation and at the same time embrace cutting-edge cataract surgery, which today is essentially refractive surgery.

New Aspheric IOL Coming Soon

A one-piece model of the Tecnis Aspheric IOL soon will be available to surgeons. "The obvious advantage of the new lens is the Tecnis aspheric surface, which provides excellent postoperative quality of vision," according to Y. Ralph Chu, M.D., Chu Vision Institute, Edina, Minn. "Also, while three-piece lenses are attractive because they can be placed in the sulcus if necessary, one-piece lenses are easier to work with for the surgeon and the OR staff." The Tecnis one-piece IOL is designed to provide additional stability and more reliable prevention of posterior capsular opacification compared with previously available single-piece lenses. It features offset haptics for three-point fixation, which applies constant outward and backward pressure. "The effect of the design is to push the optic against the capsule, which minimizes lens epithelial cell migration and also aids in keeping the lens stable in the capsular bag," Dr. Chu explains. In addition, the lens features: ■ A 360° square edge ■ Uninterrupted contact with the posterior capsular bag, including at the hapticoptic junction ■ A frosted edge to minimize glare. "In the clinical trial, we were amazed to see a very high percentage of patients with 20/20 and 20/25 vision," Dr. Chu says. "The combination of the unique lens design and the optical quality of the acrylic material really produces a 'wow factor' for patients."

Y. Ralph Chu, M.D., Chu Vision Institute, Edina, Minn., explains why: "Advances in optical measuring, mainly wavefront aberrometry, have revealed much more about what's going on in the eye. We know that how well our patients see depends not only on the lower-order aberrations young surgeons are accustomed to evaluating and treating but also on higher-order aberrations like coma and spherical aberration. This knowledge has given cataract surgeons the ability to address patients' visual status in a more meaningful way, improving the quality and not just the quantity of vision. Understanding the role of spherical aberration in less than ideal cataract surgery outcomes led to the aspheric IOL designs. Monofocal aspheric IOLs have made it easy for doctors to be refractive cataract surgeons."

The Tecnis IOL will be available soon in a one-piece model (side profile shown here) featuring a 360-degree square edge and three-point fixation for optimal stability.

Adopting the refractive cataract surgery mindset is a good way for new surgeons to stand out within the practice and the community, Dr. Packer says. "It gives patients a reason to come to you instead of going to someone else. You can differentiate yourself with your surgical and interpersonal skills, but it also helps to have some new technology up your sleeve. In that regard, aspheric IOLs are a great option to offer. You can tell patients these implants offer quality of vision that's superior to standard monofocal IOLs. They perform better in tough visual situations, such as driving at night."²

With all of his patients, Dr. Packer discusses presbyopia-correcting IOLs and their potential to provide spectacle independence. However, for various reasons, approximately 60% of patients don't choose that option. Some aren't candidates; others don't mind wearing glasses or don't see any value in spending the extra money. An aspheric IOL is a very attractive option in these cases. "I tell these patients that instead of a presbyopia-correcting IOL, we can go with an aspheric, which provides the best quality of vision of any implant available," he says. "Aspheric IOLs provide high-quality vision, and distance spectacle independence, without compromise. Patients who opt for a presbyopia-correcting IOL often are required to trade some vision quality for total spectacle independence."

If aspheric IOLs aren't used in your office, you could present them to the practice ownership as a means to upgrade services and expand your patient base. Some practices cite the added cost of aspheric lenses as a barrier to adopting them. However, all of the monofocal aspherics available in the United States have been granted New Technology IOL Status by the Centers for Medicare and Medicaid Services. Therefore, as Dr. Packer says, the extra $50 received by surgery centers should offset the costs in most situations.

Your Aspheric IOL Options

Five monofocal aspheric IOLs are available in the U.S.: two Tecnis models from Advanced Medical Optics (one acrylic, one silicone), the AcrySof IQ from Alcon, and two SofPort AO models from Bausch & Lomb one with violet shield technology, one without).

The Tecnis IOL is a negative spherical aberration lens. It's designed to fully counteract the mean amount of positive anterior corneal spherical aberration found in the general population of cataract patients, +0.27μm, leaving total spherical aberration in the average eye at zero. The Tecnis IOL is the only IOL with claims approved by the FDA for reduced spherical aberration, improved functional vision and improved night driving simulator performance.³

Several studies have demonstrated that targeting zero spherical aberration results in the best visual acuity, with quality of vision similar to that of a 20-year-old.⁴ According to Dr. Chu, "Several researchers have determined that average total spherical aberration in a 20-year-old eye, when vision is at its peak, is 0.00 μm. Wang and Koch, for example, found that with defocus of 0.0D, most eyes achieved the best image quality at spherical aberration levels between -0.10 μm and 0.00 μm. Furthermore, they concluded that it's best to leave the eye with negative, rather than positive, spherical aberration."⁵

The AcrySof IQ IOL, also a negative spherical aberration lens, is based on a somewhat different school of thought. Its design reflects studies, such as those by Levy and Legras,^6,7 indicating that the best approach for optimizing post-op vision is to compensate only partially for the positive spherical aberration found in the average anterior cornea. It adds 0.20 μm of negative spherical aberration to the eye, leaving the average eye with approximately 0.10 μm of positive spherical aberration.

The SofPort AO IOL differs from the other aspheric lenses because it's aberration-free. Therefore, it doesn't counteract any existing corneal positive spherical aberration or add any positive spherical aberration to the visual system.

Targeting Zero

All of the available monofocal aspheric IOLs provide better quality of vision than standard spherical IOLs. However, those that add negative spherical aberration to the eye should be used with caution in some cases.

Hyperopic LASIK, for example, induces negative corneal spherical aberration. Adding more negative spherical aberration by way of an IOL would adversely affect vision. "In addition, patients whose corneas are well above the norm in steepness, such as those with signs of keratoconus, are poor candidates for this type of lens because their eyes may already have high amounts of negative spherical aberration," according to Dr. Noecker. "On the other hand, patients who've had LASIK to correct myopia are ideal candidates for a negative aspheric IOL because the procedure tends to induce positive spherical aberration. And for the normal adult cataract patient population, aspheric IOLs, negative spherical aberration models included, are a better option than spherical lenses."

Maximizing Quality of Vision

"The evidence is in," Dr. Packer says. "Aspheric IOLs provide cataract patients with optical imagery they once had when they were 20 or 30 years old. More than 30 peer-reviewed papers have been published establishing that the Tecnis provides superior quality of vision compared to spherical IOLs. Furthermore, I am persuaded by the argument that targeting zero post-op spherical aberration provides the best image quality. Based on my experience, the Tecnis is the best option for two-thirds of the patients for whom a monofocal IOL is being used."

The ability to offer superior results is especially valuable to surgeons just starting out. Nothing builds a practice more effectively than satisfied patients, and what they're looking for today is quality vision. Dr. Chu's advice: "Dissect your procedures and improve at every step to ensure you're maximizing quality of vision. Build confidence and precision in your pre-op measurements, and use the best technologies, so you can treat not only lower-order aberrations and astigmatism but also residual refractive error. We've moved far beyond extracting the cataract and just being thankful to have a lens in the eye." nMD