Wavefront Weds Aberrometry
Ophthonix introduces an aberrometer for routine clinical use.
BRIAN CHOU, O.D., F.A.A.O.
Wavefront technology is no longer sequestered within research and academia, so how will it advance routine clinical optometric practice? Just as optometry started incorporating corneal topographers more than 10 years ago, wavefront is now making its initial entry into primary eye care. I've had the privilege of using Ophthonix's Z-View Aberrometer on more than 500 patients. I'll share what I've learned so far through these experiences.
Apples to oranges
Like many O.D.s, I first wondered how the wavefront-derived refraction compared with manual refraction. But latching onto this comparison diverts attention from what makes the Z-View unique.
The Z-View allows for a quantitative
measurement of higher-order aberrations.
It measures a larger number of data points than do autorefractors. I've found that the wavefront-derived refractions are similar to my manifest refractions. In some cases, the wavefront finding appears better than my refraction; in other instances, the manual refraction appears better. While I believe that subjective refraction will always have its place, the additional information provided by the Z-View helps me quickly decide what to prescribe. Chair time is precious, and like you, I don't want to spend all day giving lens choices. The Z-View reduces the patient's response burden by decreasing the necessary lens choices to reach an endpoint. Yet these benefits are no different from what existing autorefractors offer.
The Z-View is special because, unlike autorefractors, it quantifies higher-order aberrations and maximizing its capabilities requires reviewing the higher-order aberration measurements. To use the Z-View only as an autorefractor is like driving a high-performance sports car without leaving first gear.
Revealing a higher order
In the average individual, lower- order aberrations account for approximately 80% of the visual aberrations, while the remaining 20% are the higher-order variety. For the first time, the Z-View allows a quantitative measurement of higher-order aberrations. These previously ignored elements help explain why a patient has trouble during traditional refraction. I've found that a large proportion of patients who have "soft" refraction endpoints have above-average higher-order aberrations. Knowing the total refractive profile can also explain why a patient complains of poor visual quality. Finally, I've found that high-order aberrations can signal undiagnosed cataracts and corneal disorders.
While the Z-View enhances diagnosis, what I find most exciting is that it enables the nonsurgical correction of higher-order aberrations. The Ophthonix iZON spectacle lens uses the Z-View measurements to correct not only sphere and cylinder, but the higher aberrations as well. Development of wavefront contact lenses using the Z-View data is also underway.
With refractive surgery's strong adoption of wavefront aberrometry -- an area that has everything to do with clinical optics -- it's only appropriate, if not overdue, for wavefront to apply to spectacles and contact lens correction. In light of critics' warnings that optometry has strayed too far toward ocular disease, the Ophthonix
Z-View might catalyze a return to our roots of clinical optics.
DR. CHOU IS A PARTNER AT CARMEL MOUNTAIN VISION CARE IN SAN DIEGO, A CLINICAL STUDY SITE FOR VISION CORRECTION TECHNOLOGY. CONTACT HIM BY E-MAIL AT
Optometric Management, Issue: April 2005