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Wavefront technology: it is time to embrace the evolution of refraction
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Amid almost continuous advances in ophthalmic and optometric technology, the science of refraction has been a notable exception, having evolved very little until recently.
“For 40 to 50 years, we have been refracting in a similar manner: with phoropters and with the concept of subjective refraction,” said Louis J. Catania, OD, FAAO, a Primary Care Optometry News Editorial Board member. “With the explosion of technology over the course of these years, one has to find it odd that something so basic to eye care as refraction has not progressed.”
The advent of wavefront marks the potential for a new era in refraction, according to many practitioners. To stay current in this area, optometrists are encouraged to embrace this technology.
Measuring higher-order aberrations
Dr. Catania cited a statement made by prominent refractive surgeon Stephen Slade, MD, about 5 years ago. “He said that the weakest link in refractive surgery is the refraction,” Dr. Catania said. “And from that point on, we have recognized that this is indeed the case. We have been measuring only a portion of patients’ vision.”
Dr. Catania said it is now known that a large amount of refractive error consists of higher-order aberrations. “We now recognize that at least 20%, if not more, of patients’ vision is engrossed in higher-order aberrations,” Dr. Catania said. “And wavefront gives us the ability to measure both lower- and higher-order aberrations in an objective way, without having to rely upon the patient’s response.”
According to John Potter, OD, FAAO, another Primary Care Optometry News Editorial Board member, wavefront technology for refractive surgery is helpful not only in terms of visual acuity, but also in improving night vision problems. “Taking higher-order aberrations into account in the treatment plan for laser vision correction gives patients a better chance of seeing 20/20,” he told Primary Care Optometry News. “It also reduces patients’ chances of night vision problems following their surgery.”
Dr. Potter emphasized, however, that wavefront is not necessarily always the superior method of refraction for refractive surgery. “Only 10% to 15% of our current candidates for refractive surgery have significant higher-order aberrations,” he said. “We began to notice that, in many of these patients, the wavefront analysis for refractive error would be significantly different from the manifest or subjective refraction.”
Dr. Potter said this presents a challenge to the practitioner, who must then use both the wavefront and subjective data to determine the best prescription for the patient. “You have to use your clinical judgment and decide,” he said. “Wavefront analysis gives the doctor more information to determine the final prescription.”
Wavefront and contact lenses
According to Garold L. Edwards, OD, a practitioner based in Felton, Calif., the area of contact lenses — not refractive surgery — may provide the best use for wavefront technology.
“The truly ideal correction for wavefront is contact lenses,” Dr. Edwards said. “With contact lenses, you are putting exactly the right power exactly where it needs to be. You can stabilize the lens so it doesn’t rotate, and you can place it on the eye so you are always looking through the center of the optics.”
Contact lenses are also compatible with wavefront in terms of changes in correction and the need to update prescriptions, Dr. Edwards said. “We know from studies that even higher-order aberrations in a very normal eye change throughout our lifetimes,” he said. “As the crystalline lens of the eye continues to grow and we begin to develop cataracts, we continue to have a change, especially in the higher-order aberrations.”
For this reason, Dr. Edwards said he finds contact lenses to be more complementary to wavefront technology. “You could go back every 12 months and have your LASIK touched up,” he said. “But how much better would it be to be able to go in every 12 months, have a new wavefront refraction — and have new contact lenses made?”
Dr. Edwards added that wavefront-designed contact lenses are not “rotationally symmetric,” which provides more precise correction.
“When we put a toric soft lens on the eye, or when we put a spectacle lens on that eye, we are using a correction that is rotationally symmetric. On one side, it might have a little bit too much power, and on the other side, there’s not enough power,” he said. “But when you put a wavefront soft contact lens on the eye, you have an exact correction for the whole 360°.”
Wavefront’s future in optometry
With so many potential applications in the area of refraction and contact lenses, wavefront technology seems likely to figure prominently into the future of optometry. But will it supplant traditional refraction?
“Wavefront gives us the ability to measure both higher- and lower-order aberrations in an objective way,” Dr. Catania said. “Given that, one has to believe that during the next 5 to 10 years, this form of refraction will replace what we have been doing for the past 40 to 50 years.”
While Dr. Potter believes that wavefront will be an exciting part of the future of eye care, he cautioned against relying solely on wavefront data. “The wavefront data may not be better than the patient’s subjective refraction,” he said. “Sometimes it is, and sometimes it’s not. You can’t just go by the wavefront data by itself; you would be very unhappy.”
Dr. Catania emphasized that because refraction is a fundamental part of the optometric profession, optometrists should embrace a technology such as wavefront, which promises to advance the science of refraction. “If we are, in fact, the vision care specialists in the health care field, we can’t afford not to embrace the evolution of refraction,” he said. “Probably 80% to 90% of our patients come to us for vision care. That is a large part of the care we provide.”
Dr. Catania added that, in recent years, the focus of optometry has shifted from refraction to therapeutics and ocular disease management. While he said the goal was to expand the scope of optometric practice, this may have been accomplished at a cost.
“The emphasis has been on expanding the scope of practice in those other areas, at the expense of our fundamental skill,” he said. “I was very much a part of therapeutics in optometry at that time. A lot of my critics said, ‘you’re moving us away from refraction.’ The sad thing is, my critics were right.”
Dr. Catania noted the irony of this shift: while optometrists were seeking to expand into areas formerly restricted to ophthalmology, the newest technology in refraction was becoming the province of ophthalmologists.
“We virtually created a void in vision care,” he said. “And that void is being filled by our colleagues on the ophthalmology side. The sad part is, that void is being filled with new and exciting technologies like wavefront, which optometry hasn’t really begun to grasp yet. Clearly, it could become a crisis in our profession.”
Better than 20/20
Dr. Catania said with the implementation of wavefront refraction, correcting to 20/20 may no longer be the goal.
“I don’t think 20/20 will be our goal anymore, now that we are able to recognize and measure the higher-order aberrations and what they do to vision,” Dr. Catania said. “The next step is to correct them. And interestingly enough, that is probably going to take place more with synthetic approaches rather than surgical approaches.”
Dr. Catania said the first level of this approach would be intraocular lenses, then contact lenses and spectacle lenses.
“Those are the synthetic potential for correcting higher-order aberrations,” he said. “Only a portion of that is going to be surgical, and the rest of it is going to be non-surgical, which optometry will be able to manage and control.”
Dr. Potter said the concept of wavefront technology and the future of optometry is an exciting one. “I am very excited about this,” he said. “It is just a tremendous opportunity for optometry. Wavefront analysis has opened up a door for optometry to use its basic vision science — of which we are the masters — and turn that into a direct clinical application.”
For Your Information:
- Louis J. Catania, OD, FAAO, is a Primary Care Optometry News Editorial Board member who is associated with Nicolitz Eye Consultants in Jacksonville, Fla. He can be reached at 1235 San Marco Blvd., Jacksonville, Fl, 32207; (904) 398-2720; fax: (904) 398-6408.
- John Potter, OD, FAAO, is a Primary Care Optometry News Editorial Board member who practices in Dallas. He can be reached at 4203 Hollow Oak Dr., Dallas, TX 75287-6846; (972) 818-1239; fax: (972) 818-1240.
- Garold L. Edwards, OD, FAAO, is a practitioner based in Felton, Calif. He can be reached at 2091 Upper Scenic Dr., Felton, CA 95018-9645; (408) 221-3860; e-mail: gledwards@prodigy.net.