Article Date: 6/1/2007

Minimizing Refractive Errors

Minimizing Refractive Errors

Learn how the latest in aberrometry can improve and possibly change the way you perform refractions.

Dr. Karpecki: Many of us are starting to use the wavefront aberrometer as an autorefractor. Is that the case for you?

Dr. Lowe: Yes, but not solely. We've always prided ourselves on performing great refractions. We still run our patients through our autorefractor, however, because it has a keratometer in it. When we started using the Z-View Aberrometer, we saw that, in most cases, our refraction, autorefractor and wavefront readings all correlated. When they didn't, the aberrometer usually provided the accurate prescription. I continued to perform a conventional refraction with retinoscopy until I realized how redundant it had become.

Dr. Campisi: We had the same experience. I haven't picked up my retinoscope in a while. I prescribe lenses right from my Z-View.

Modifying a prescription

Dr. Gindoff: Does everyone on the panel prescribe an iZon lens according to the Z-View Aberrometer readings? Or do you modify the lower-order aberrations (sphere, cylinder and axis) on the prescription printout form, thereby keeping the neutralization for the higher-order aberrations?

Dr. Quon: As I understand it, the protocol for using the Z-View to prescribe iZon lenses is to use the cylinder and axis as is and possibly modify the sphere as needed. I begin each refraction with the Z-View's readings. If I get a soft refraction, generally I'll use the results from the Z-View and modify the sphere slightly. If I get a refraction with a 20° difference in axis as compared to the reading recommended by the Z-view, I use my own manifest refraction.

Dr. Gindoff: Are you still ordering the iZon lens with your phoropter data?

Dr. Quon: Generally, I do. I may modify the data if I have a refraction that's between quarter-diopter steps. Then, I'll choose the 1/8th diopter that's indicated.

Dr. Gindoff: We've just begun to prescribe in 1/8ths since introducing the Z-View Aberrometer. I do this even when I prescribe for a lens other than the iZon. The lab personnel aren't thrilled about this, but I do it for the patient's benefit.

Dr. Campisi: I agree that it's more difficult to illustrate 1/8 diopter prescriptions to a patient sitting behind a phoropter. I also agree that the smaller prescriptions create more of an impression for patients with HOAs. Traditionally, I wouldn't prescribe for +/-.25 or less. The Z-View has altered the way I prescribe. Now I tell my patients: "Look, if you take this prescription anywhere else, the staff will probably laugh at you because the prescription is so small. I've never worked in such small increments until I acquired this technology, but the advantages are greater than what one would expect when combining this with the iPrint data.

Wavefront technology … has the potential to revolutionize patient care in the way we perform refractions, detect disease and improve vision.
Paul M. Karpecki, O.D.

Refracting and scanning techniques

Dr. Gindoff: Do you refract more for progressive or single-vision iZons?

Dr. Campisi: I prescribe more progressives than single-vision iZon lenses. Also, I should note that I always perform binocular testing, so I don't disregard the entire refractive process. I do near and far phorias, which are crucial when prescribing PALs. If a patient has a high phoria at near, I perform base out-compensating vergences to ensure they can get their eyes into the progressive channel. If they can't, I'll prescribe some base-in prism so they can better converge at near, making it easier to adapt to the PAL.

Dr. Gindoff: I think iZons are different, though, because I can find the channel. It's wonderful.

Dr. Campisi: Adaptation is difficult for a patient with 12 prism diopters of exophoria or convergence insufficiency no matter what progressive brand you use.

I'd noticed that my high exophoria patients weren't scanning accurately. One of the engineers at Ophthonix, the manufacturer of the Z-View Aberrometer, suggested I scan monocularly if a patient had poor binocular vision. The Z-View gave me a better refraction when I had the patient fixate monocularly on the instrument. I use this philosophy in reverse sometimes. If a patient doesn't scan accurately, I investigate the binocular system more closely. Nine times out of 10, they're good candidates for vision therapy.

Expanding utility

Dr. Karpecki: With the Z-View Aberrometer, as we've discussed, you no longer need to perform retinoscopy. Your staff has incorporated the technology into the screening process. Does this help with patient flow?

Dr. Quon: I'd like to see an auto-keratometer or a topographer combined with the Z-View.

Dr. Campisi: I'm hoping the Z-View will be paired with a digital refracting device some day, because transferring the data from the Z-View to the phoropter can slow the refractive process down. Digital technologies enable the AR/AK information to be wired into the digital phoropter. I plan to purchase a digital refraction system this year to work with the Z-View Aberrometer.

Dr. Gindoff: The aberrometer can slow down the screening process in the beginning, but the exam becomes more efficient once you and your technicians become accustomed to how it works. My aberrometer isn't linked to the phoropter. We take five scans, which requires more time, but I prescribe from the aberrometer data. This is the first instrument that's enabled me to write prescriptions accurately without having to use other equipment. I recently learned, however, that the most recent software release for the Z-View does include the interface required for commercially available digital phoropters.

Dr. Campisi: Sometimes, to improve efficiency, I scan patients who aren't going to receive iZon lenses, such as children, because the refraction is so accurate.

Dr. Lowe: Scanning patients who we know may not be candidates for iZon lenses has streamlined my refraction process as well. I'm able to perform refractions much more quickly. I still do binocular checks, but scanning all patients cuts down on my refraction time. This gives me more time to talk to them about their visual needs, which I didn't have before.

I begin each refraction with the Z-View's readings. If I get a soft refraction, generally I'll use the results from the Z-View and modify the sphere slightly.
Daniel E. Quon, O.D.

New way to practice

Dr. Karpecki: Does this technology have the potential to change the way optometrists perform refractions? Dr. Layman, as the doctor who was named optometrist of the year in 2006, what do you think?

Dr. Layman: This technology is for any practitioner interested in differentiating his or her practice as cutting-edge. Only the discriminating patient will expect a tool like this that offers such an advanced degree of clarity as well as an opportunity for more incisive diagnoses and more accurate correction.

Dr. Campisi: With the introduction of digital refractions, it's acceptable within our community to use the aberrometer as an autorefractor. From the patient's perspective, when they sit behind the Z-View Aberrometer and find out it will take less than a minute, and there's no need to say "one" or "two" anymore, they get excited.

Revolutionizing patient care

Dr. Karpecki: Using wavefront technology to customize spectacle lenses for patients is, indeed, exciting. It has the potential to revolutionize patient care in the way we perform refractions, detect disease and improve vision. The more we talk about the benefits of this technology and how it can significantly improve the lives of patients, the more likely our colleagues will be to introduce it and transform their practices. OM

Optometric Management, Issue: June 2007