Premium IOLs offer improved quality of vision

Issue: September 2006

ByMarc R. Bloomenstein, OD, FAAO

Marc Bloomenstein, OD [photo]
Marc Bloomenstein

Today I am finding I have more choices related to which pseudophakic lens I should recommend to my patients. In the year 2006 we are at the dawn of some amazing technology — and I am not talking about LASIK surgery, though I am speaking “refractively.”

Whether your patient has cataracts or is simply looking to improve his or her quality of life or quality of vision, and unless you have been living in a cave, you realize that standard IOLs are being replaced with new premium IOLs. These lenses are capable of correcting vision beyond simply sphere or cylinder. Aside from presbyopia-correcting lenses, we now have lenses that minimize wavefront-related aberrations and, thus, improve quality of vision.

Available premium lenses

Two lenses — the AMO Tecnis Z9000 (Irvine, Calif.) and Alcon AcrySof IQ (Fort Worth, Texas) — have been approved as new technology IOLs (NTIOLs) by the Center for Medicare and Medicaid Services (CMS) and, thus, are reimbursed at a higher rate than standard implants. The Bausch & Lomb SofPort AO (Rochester, N.Y.) is awaiting approval. More importantly, the CMS ruling implies that there is a benefit to patients and that the higher cost of this technology is worth the added expense. These lenses, however, are not all the same; they differ in both design and performance.

The commonality of these “quality of vision” lenses is found in the design to decrease the amount of unwanted aberration that follows standard IOL surgery. The young healthy eye has a balance of positive spherical aberration on the cornea with that of negative spherical aberration in the lens. In fact, as we age, the magnitude of positive spherical aberration on the lens increases, thus leaving the eye with unwanted spherical aberration.

Positive spherical aberration is known to be responsible for common night vision distortions, such as glare, halo and poor contrast sensitivity. Putting a traditional spherical IOL into an older eye compounds the problem by further increasing the amount of positive spherical aberration.

In the geriatric population, which may have other conditions contributing to the decrease in vision, eliminating unwanted aberrations after cataract surgery seems paramount. These newer lenses with aspheric or modified prolate surfaces are an attempt to minimize the distortion by better imitating the curvature of the cornea.


Bausch & Lomb SofPort AO: This aspheric lens is designed to be aberration neutral.

AMO Tecnis IOL: Available in both acrylic (left) and silicone (right) platforms, this lens has a prolate surface that induces negative spherical aberration, thereby reducing or eliminating total spherical aberration. Source: AMO

Tecnis IOL

The Tecnis IOL, available in both silicone and acrylic platforms, has a prolate surface that induces negative spherical aberration, thereby reducing or eliminating total spherical aberration. The Tecnis IOL was specifically designed to compensate for the average amount of corneal spherical aberration present in the cataract patient population. As a result, numerous studies demonstrate that the aspheric Tecnis lens reduces overall spherical aberration, leading to improved functional vision and contrast sensitivity. Incorporating the Z-sharp optic technology to flatten the curvature in the anterior surface of the lens produces the modified prolate surface and, in turn, creates negative spherical aberration. The introduction of Z-sharp technology into the IOL necessitates the correct centration and tilt of the Tecnis to avoid inducing new aberrations.

Acrysof IQ: The optics of this lens were designed to offset the positive spherical aberration of the cornea by inducing negative spherical aberration with the lens.
Source: Alcon

The aspheric Tecnis lens has clinical data showing a reduction in spherical aberration and improved night driving.

AcrySof IQ

Alcon’s AcrySof IQ IOL is designed to provide improved image quality and is based on the proven AcrySof Single-Piece acrylic platform that also incorporates UV and blue-light filtering chromophores. The unique optics of the lens were designed to offset the positive spherical aberration of the cornea by inducing negative spherical aberration with the lens. This was accomplished by reducing central optic thickness and maintaining a thin edge profile.

SofPort AO

The SofPort AO aspheric lens, unlike the Tecnis and IQ, is designed to add no aberration. Instead, the lens is designed to be aberration free, with uniform center-to-edge power for optical performance unaffected by pupil size or location of the optic. This lens can be considered free of tilt or decentration issues that may plague the aspheric lenses.

Of these lenses, the Tecnis IOL is the only wavefront-designed lens with claims approved by the FDA for reducing spherical aberration and improving functional vision and night driving. It has been shown to provide patients with contrast sensitivity that is better than conventional IOLs and also similar to or better than the contrast sensitivity of normal control subjects.

Safety implications

An attribute of all of these lenses is the safety implications, especially concerning night driving. (Ginsburg A, Kelly M. Functional vision testing: night driving simulator studies. Presented at ASCRS-ASOA; April 1-5, 1995. San Diego, Calif.) In one study, patients who received an aspheric IOL and simulated driving 55 miles per hour on a dark highway were capable of identifying a pedestrian from 45 feet further away than those with traditional IOLs. Driving simulations on city streets and rural highways, with and without glare, showed improvement identifying pedestrians and various colored signs in nearly every category as well. The National Highway Traffic Safety Administration states that most pedestrian accidents are most likely to occur at night. Therefore, the added 45 feet for drivers may initiate a braking response faster and reduce the fatalities.

Furthermore, the ability of an IOL to improve contrast sensitivity in low lighting conditions has great implications for reducing falls and generally improving function and quality of life in older adults. This improvement in contrast can also help professions that depend on best quality of vision in mesopic conditions such as pilots, professional drivers and police officers, to name a few.

This is the exact opposite of the multifocal lenses, which induce dysphotopsia and are unsuitable for patients with night demands. The conflict between multifocality and aberration correction is the reason the development of the Tecnis multifocal lens could be beneficial. This lens will both add presbyopic correction and improve quality of vision.

I fervently believe that optometry is positioned to guide patients into the best surgical decision associated with their specific needs. Choices are a good thing — they provide us the opportunity to modify treatment plans and create opportunities that will allow patients to dictate their quality of vision. There is no doubt that we want the best for our patients, and these aspheric lenses can do more for our patients than standard implants. The choices will become clearer when you take the time to talk to your patients and learn what is most important to them.

For more information:

Marc Bloomenstein, OD, FAAO, is a member of the Editorial Board of Primary Care Optometry News and refractive clinic medical director at Barnet Dulaney Perkins Eye Center in Phoenix. He can be reached at 4800 N. 22^nd St., Phoenix, AZ 85016; (602) 955-1000; fax: (602) 508-4744; e-mail: Mbloomenstein@BDPEC.com. Dr. Bloomenstein has no direct financial interest in the products mentioned in this article, nor is he a paid consultant for any companies mentioned.