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The past and future of refractive surgery: Wavefront technology will revolutionize the field
As part of our celebration of the 20th anniversary of Ocular Surgery News, Section Editors look at how things have changed and what the future holds. This month, Daniel S. Durrie, MD, on refractive surgery.
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The past 20 years of ophthalmology have seen numerous groundbreaking developments in anterior segment surgery. I have been fortunate enough to have been involved with many of them.
It has been a privilege for me to have worked with many companies as a consultant throughout my career and to have had firsthand exposure to the creation of cutting-edge technologies.
The milestones in technology have been many. They have shaped the industry and our practices. Some that have irrevocably changed the practice of ophthalmology were the widespread adoption of IOLs, phacoemulsification and, in the past decade, LASIK technology. Each of these technologies has, in its own right, represented a giant leap forward for ophthalmology.
Yet, all along, something has been missing – until now. With the advent of wavefront diagnostic devices, for the first time ever, eye doctors have a window into how the eye really works. Some might argue that to place such importance on the impact of wavefront diagnosis is to overstate the case.
I would counter that not to see the importance of this is to miss out on the wave of the future and on one of the great technological advances in eye care. With wavefront-guided laser surgery, we are merely scratching the surface of where this relatively unexplored technology can take us. Wavefront technology has the potential to help us truly assess and understand how and what the patient really sees. With this more comprehensive understanding of the patient’s aberrations comes an increased capacity and responsibility to correct them.
As George Pettit, MD, PhD, of Alcon stated in front of the Food and Drug Administration’s Ophthalmic Device Panel, wavefront sensing provides a “measurement of how the eye functions as a fully integrated optical system and gives us a map, kind of a road map, of the pupil.”
The challenge is for us to be able to step out of the “phoropter world” to examine the new possibilities from a wavefront perspective. In the phoropter world, we assume that every –2 D eye has the same optics. We assume every cylinder is symmetrical. Thus far, however, we have not had access to technology that enables us to make more nuanced distinctions.
An improvement
We have all seen cases in which we are able to use conventional LASIK to correct lower-order aberrations, such as defocus and astigmatism, but have left patients with other distortions, such as halos, glare and impaired night vision. This is because, with conventional LASIK, we are unable to see the true complexity and the interrelation of the aberrations. We can see different aberrations independently, but we have no complete map of their relationship with one another.
Another complicating factor is that the amount of higher-order aberrations the population experiences is not at all related to the level of myopia. In other words, patients with –1 D can have just as many higher-order aberrations as those with –8 D. This means refractive surgery that addresses only sphere and cylinder may not improve a patient’s overall vision.
With wavefront analysis, however, we can really see the whole problem and treat it as such. We can begin to understand that not everyone’s visual map is the same.
Custom ablation, for example, allows us to avoid increasing spherical aberration, thereby significantly improving halos at night. Studies have found that patients treated with custom ablation experience improvements in glare, halo, night driving, blurred vision and fluctuation of vision.
Variety of applications
Yet the promise held by wavefront-guided devices does not stop with custom ablation. Wavefront devices have come a long way since the original bulky prototypes first used, and we are now brainstorming on and experimenting with numerous exciting prospects.
Now that some of the devices are so small, the possibilities are virtually limitless. One idea that is currently in development is wavefront-guided contact lenses, which could be customized to the individual’s eye using digital information. Another possibility is to adjust IOLs digitally inside the eye with a wavefront device.
Another promising area of research is the IntraLase FS femtosecond laser, which could have an important role in wavefront-guided LASIK surgery. This computer-controlled laser is expected to make creating flaps more precise and consistent and make intrastromal adjustment possible.
Wavefront technology could be used is other exciting ways. For example, perhaps we could use it for intrastromal correction of hyperopia, or to change the shape of the cornea. The technology exists – we just need to be creative.
If we ride the wave of custom ablation, we will find that these devices will keep getting better and more sophisticated. Whatever new device comes down the road, I issue a challenge to the industry to start thinking in a wavefront-guided world.
A note from the editors:
This article is based in part on Dr. Durrie’s Barraquer Lecture, delivered at this year’s American Academy of Ophthalmology meeting.
For Your Information:
- Daniel S. Durrie, MD, can be reached at Hunkeler Eye Institute, 5520 College Blvd, Overland Park, KS 66211; (913) 491-3737; fax: (913) 491-9650. Dr. Durrie has no direct financial interest in the products mentioned in this article. He is a paid consultant for Nidek, Bausch & Lomb and Alcon.