Most people who have LASIK are very pleased with their new vision without glasses. But in some cases, a person may feel their eyesight isn’t as distinct after surgery as it was with eyeglasses or contact lenses. Even if they can see letters on the “20/20” line on the eye chart, their vision might not be as “sharp” as they remember.

In many cases, a second LASIK procedure (called an enhancement) can be performed to improve visual clarity and satisfaction. But enhancement surgeries tend to have a higher risk of complications than first-time LASIK procedures, and sometimes an enhancement is not recommended, such as when the patient’s cornea is too thin for additional surgery.


The problem: Higher-order aberrations

When a person is dissatisfied with their vision after LASIK, it is usually due in part to subtle optical imperfections called higher-order aberrations, or HOAs. These imperfections can cause or contribute to blur, glare, loss of contrast, and night vision problems (including starbursts and halos around street lights and vehicle headlights).

Research suggests that prior to vision correction surgery, up to 20 percent of a person’s vision problem can be due to HOAs. After LASIK surgery, this percentage can be much higher. And nearly all of us — whether we’ve had vision correction surgery or not — have some degree of higher-order aberrations. At least one study suggests that 96 percent of nearsighted individuals have significant levels of HOAs.

Unfortunately, unlike refractive errors (nearsightedness and farsightedness, with or without astigmatism) higher-order aberrations cannot be addressed with conventional eyeglasses. People who feel the need for corrective lenses for night driving after LASIK often find regular eyeglasses provide little or no help in sharpening their eyesight.


The technology: Wavefront analysis

Until recently, the prescription for eyeglasses, contact lenses and refractive surgery such as LASIK, was determined by a traditional refraction. This process, performed by a machine (automated refractor) or done manually by your eye doctor (by dialing different lenses in front of your eyes and asking, “Which lens is better — lens 1 or lens 2?”) is not able to identify the HOAs that affect vision.

To address this shortcoming of traditional vision correction, optical technology called wavefront analysis was adapted for measuring eyes prior to LASIK surgery. In wavefront analysis, a special automated instrument called an aberrometer is used to detect and measure higher order aberrations as well as traditional refractive errors. Wavefront analysis provides a very precise mapping of the surface of your eye that details both the traditional refractive error and HOAs. These highly-detailed measurements are then used to program the excimer laser in wavefront-guided LASIK to provide better outcomes than standard LASIK.

But as precise as wavefront-guide LASIK is, every person’s cornea responds to laser energy uniquely and heals differently. And the laser treatment itself induces some HOAs while it corrects others. So in many cases, significant HOAs remain after LASIK surgery — even after the more precise, wavefront-guided procedure.


The solution: iZon High Resolution Lenses

iZon High Resolution Lenses

Ophthonix, Inc. (Vista, CA) saw an opportunity to use the advances of wavefront technology to create a new generation of eyeglass lenses capable of addressing HOAs as well as refractive errors. The wavefront-guided lenses created with this technology — called iZon® High Resolution Lenses — are capable of producing sharper vision than conventional eyeglass lenses. According to the company, iZon Lens provides wearers with the benefit of “High-Definition Vision.”

Though iZon Lenses are available for anyone who needs corrective lenses, they are especially good “problem-solver” lenses for individuals who’ve had LASIK or other vision correction surgery and still have issues with their eyesight.


What’s different about iZon Lenses

The first thing you’ll notice when being evaluated for iZon Lenses is the equipment used to measure your eyes. In addition to the standard equipment you’ve seen at eye exams in the past, your eye doctor or a technician will measure your eyes with a diagnostic instrument called a Z-View® Aberrometer. Using wavefront analysis technology, the Z-View Aberrometer gathers data from more than 10,000 reference points on each of your eyes.

The measurements take about a minute and the machine generates an iPrint™, which is likened to an optical “fingerprint” of your eye’s need for vision correction. The iPrint is then reviewed by your eye doctor and used by Ophthonix to manufacture iZon High Resolution Lenses that are customized to address the vision problems caused by your eyes’ unique imperfections, including higher-order aberrations.

The iZon Lenses are available in single vision (for nearsightedness and farsightedness, with or without astigmatism) and also in a progressive (“no-line bifocal”) lens design for people over age 40 who need a multi-focal correction due to presbyopia.


Night driving benefits of iZon Lenses

Even people who feel they see quite well during the day complain of night vision problems. This is particularly true for older drivers.

To evaluate the benefits of iZon Lenses for nighttime driving, Ophthonix commissioned a study conducted at the U.S. Navy Refractive Surgery Center in San Diego using an FDA-validated nighttime driving simulator. The night driving simulation included 12 tests, where the subjects had to detect and then identify potential hazards, in both glare and non-glare conditions.

In all 12 tests, the iZon Lenses improved reaction time (compared to conventional eyeglass lenses), with the results being statistically significant in seven of the 12 tests. In one of the tests involving an image of a pedestrian near the highway in glare conditions, the iZon Lenses improved reaction time to the extent that they would allow a driver traveling at 55 mph to stop 20 feet shorter for a greater margin of safety in this situation.


What eye care professionals are saying about iZon Lenses

Refractive surgeons and optometrists alike are finding the iZon Lenses to be of great benefit to many of their patients.

Mihir (Max) Parikh, M.D., a prominent LASIK surgeon in La Jolla, California, has found iZon Lenses to be very beneficial for patients who are “almost happy” with the results of LASIK surgery, but are not good candidates for surgical enhancement. “These patients are legal for driving without glasses, and may even see the 20/20 line on a standard eye chart, but they still have some visual complaints, particularly at night,” says Dr. Parikh. “We’ve found the iZon Lenses to be a very effective solution in these situations, and significantly more beneficial than regular eyeglasses.”

Dr. Parikh estimates that perhaps 5 percent to 10 percent of LASIK patients nationwide could benefit from iZon Lenses after surgery.

Keith Wan, O.D. at nearby Scripps Poway Eyecare was one of the first eye doctors in the U.S. to adopt the new technology of iZon High Resolution Lenses, and has been prescribing the lenses for more than two years. Dr. Wan performs Z-View Aberrometer measurements for all of his patients as part of their comprehensive eye exam.

“People who struggle with their vision when driving at night are probably the best candidates for iZon Lenses,” says Dr. Wan. “In our experience, perhaps 50 percent to 60 percent of those who need eyeglasses or contact lenses could see better with iZon Lenses.”

Daniel Quon, O.D. in Costa Mesa, California is another primary care optometrist who is a firm believer in the benefits of iZon Lenses. “”I tell patients that subjectively they will experience a 10 to 20 percent increase in resolution, contrast, and improvement in night vision,” says Dr. Quon.


What iZon Lens wearers are saying

Though results will vary from person to person, many people fit with iZon Lenses report that they are the first lenses they’ve ever had that enable them to drive comfortably at night, according to Ophthonix. Others have reported that objects appear more defined and three-dimensional with iZon Lenses, compared to their previous eyeglasses with conventional lenses. Improvements in contrast and the vibrancy of colors have also been noted with iZon Lenses, says the company.

Eye doctors who prescribe iZon Lenses say most of the patients they fit with the lenses are very pleased with the new technology and will purchase iZon High Resolution Lenses again.


How much do iZon Lenses cost?

As with any advanced technology, iZon Lenses are priced at a premium compared to conventional eyeglass lenses. You can expect to pay about 25% more for the iZon Lenses. But for LASIK patients and other people who may lack crisp, sharp vision (especially when driving at night), iZon Lenses may well be worth the added expense.


Where to find iZon Lenses

To find an eye doctor near you that prescribes iZon Lenses, visit Ophthonix’s website at www.izonlens.com.